Hamtronics receiver issue with AllStar RTCM
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics. http://www.hamtronics.com/r303.htm When hooked up to the discriminator on the hamtronics board, I could not get the RTCM to calibrate squelch. It usually told me the audio was too low weather the RX level was bumped up or down. I then hooked it up to a motorola SM50 and it calibrated shortly after adjusting RX levels. So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output. Here is the SM50 discriminator out: amsatnet.info/SM50.png Here is the hamtronics discriminator out: amsatnet.info/HAMTRONICS.png Here is an audio sample comparing them (you can probably guess which radio is first): amsatnet.info/Sm50_hamtron_DISC.wav Does anybody else have experience with hamtronics receivers? Thanks, Skyler KD0WHB
Try adding JP1 in the RTCM. This gives some gain to the squelch noise amp. If that works you'll want to turn on the RTCM's BEW (#17 on the main menu). If it's not on that menu you'll need to download the proper firmware and upgrade. This help radios with low out of band discriminator noise not false the squelch on voice peaks. There 3 settings 0) off, 1) on, and 3) on with more aggressive locking. But first make sure you can calibrate the squelch with JP1 in. Otherwise your SOL and there's no reason to upgrade. In that case you'll have to buy some other radios for your voters. On Sun, Mar 27, 2016 at 2:12 PM, Skyler F <electricity440@gmail.com> wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
http://www.hamtronics.com/r303.htm
When hooked up to the discriminator on the hamtronics board, I could not get the RTCM to calibrate squelch. It usually told me the audio was too low weather the RX level was bumped up or down. I then hooked it up to a motorola SM50 and it calibrated shortly after adjusting RX levels.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Here is the SM50 discriminator out: amsatnet.info/SM50.png
Here is the hamtronics discriminator out: amsatnet.info/HAMTRONICS.png
Here is an audio sample comparing them (you can probably guess which radio is first): amsatnet.info/Sm50_hamtron_DISC.wav
Does anybody else have experience with hamtronics receivers?
Thanks, Skyler KD0WHB
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-- -- Tim
Ok, so JP1 is just for the squelch amp? the RX levels are fine. When I ignored squelch, I could easily get a 3khz tone to show at 3khz on the menu. On Sun, Mar 27, 2016 at 4:23 PM, Tim Sawyer <tisawyer@gmail.com> wrote:
Try adding JP1 in the RTCM. This gives some gain to the squelch noise amp.
If that works you'll want to turn on the RTCM's BEW (#17 on the main menu). If it's not on that menu you'll need to download the proper firmware and upgrade. This help radios with low out of band discriminator noise not false the squelch on voice peaks. There 3 settings 0) off, 1) on, and 3) on with more aggressive locking.
But first make sure you can calibrate the squelch with JP1 in. Otherwise your SOL and there's no reason to upgrade. In that case you'll have to buy some other radios for your voters.
On Sun, Mar 27, 2016 at 2:12 PM, Skyler F <electricity440@gmail.com> wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
http://www.hamtronics.com/r303.htm
When hooked up to the discriminator on the hamtronics board, I could not get the RTCM to calibrate squelch. It usually told me the audio was too low weather the RX level was bumped up or down. I then hooked it up to a motorola SM50 and it calibrated shortly after adjusting RX levels.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Here is the SM50 discriminator out: amsatnet.info/SM50.png
Here is the hamtronics discriminator out: amsatnet.info/HAMTRONICS.png
Here is an audio sample comparing them (you can probably guess which radio is first): amsatnet.info/Sm50_hamtron_DISC.wav
Does anybody else have experience with hamtronics receivers?
Thanks, Skyler KD0WHB
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-- -- Tim
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
Honestly.....With $25 Maxtracs all over the place.......why.....WHY would you want to screw around with anything Hamtronics makes....seriously..... On Sun, Mar 27, 2016 at 3:23 PM, Tim Sawyer <tisawyer@gmail.com> wrote:
Try adding JP1 in the RTCM. This gives some gain to the squelch noise amp.
If that works you'll want to turn on the RTCM's BEW (#17 on the main menu). If it's not on that menu you'll need to download the proper firmware and upgrade. This help radios with low out of band discriminator noise not false the squelch on voice peaks. There 3 settings 0) off, 1) on, and 3) on with more aggressive locking.
But first make sure you can calibrate the squelch with JP1 in. Otherwise your SOL and there's no reason to upgrade. In that case you'll have to buy some other radios for your voters.
On Sun, Mar 27, 2016 at 2:12 PM, Skyler F <electricity440@gmail.com> wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
http://www.hamtronics.com/r303.htm
When hooked up to the discriminator on the hamtronics board, I could not get the RTCM to calibrate squelch. It usually told me the audio was too low weather the RX level was bumped up or down. I then hooked it up to a motorola SM50 and it calibrated shortly after adjusting RX levels.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Here is the SM50 discriminator out: amsatnet.info/SM50.png
Here is the hamtronics discriminator out: amsatnet.info/HAMTRONICS.png
Here is an audio sample comparing them (you can probably guess which radio is first): amsatnet.info/Sm50_hamtron_DISC.wav
Does anybody else have experience with hamtronics receivers?
Thanks, Skyler KD0WHB
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-- -- Tim
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Because the Denver Radio club wants to On Sun, Mar 27, 2016 at 5:05 PM, Kirk Just Kirk <wb6egr@gmail.com> wrote:
Honestly.....With $25 Maxtracs all over the place.......why.....WHY would you want to screw around with anything Hamtronics makes....seriously.....
On Sun, Mar 27, 2016 at 3:23 PM, Tim Sawyer <tisawyer@gmail.com> wrote:
Try adding JP1 in the RTCM. This gives some gain to the squelch noise amp.
If that works you'll want to turn on the RTCM's BEW (#17 on the main menu). If it's not on that menu you'll need to download the proper firmware and upgrade. This help radios with low out of band discriminator noise not false the squelch on voice peaks. There 3 settings 0) off, 1) on, and 3) on with more aggressive locking.
But first make sure you can calibrate the squelch with JP1 in. Otherwise your SOL and there's no reason to upgrade. In that case you'll have to buy some other radios for your voters.
On Sun, Mar 27, 2016 at 2:12 PM, Skyler F <electricity440@gmail.com> wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
http://www.hamtronics.com/r303.htm
When hooked up to the discriminator on the hamtronics board, I could not get the RTCM to calibrate squelch. It usually told me the audio was too low weather the RX level was bumped up or down. I then hooked it up to a motorola SM50 and it calibrated shortly after adjusting RX levels.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Here is the SM50 discriminator out: amsatnet.info/SM50.png
Here is the hamtronics discriminator out: amsatnet.info/HAMTRONICS.png
Here is an audio sample comparing them (you can probably guess which radio is first): amsatnet.info/Sm50_hamtron_DISC.wav
Does anybody else have experience with hamtronics receivers?
Thanks, Skyler KD0WHB
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
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-- -- Tim
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-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
On 3/27/16 5:12 PM, Skyler F wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Does anybody else have experience with hamtronics receivers?
Yes, I have a number of them in place and find they work perfectly with the RTCM. It can give about 2v P-P on the discriminator pin, and has the high frequency compute the RTCM squelch needs. My prime setup is here: http://gallery.keekles.org/d/28384-2/0330141929a.jpg Note you'll want to put a cap in line, as the discriminator is DC coupled in the hamtronics. Can you put a scope on the discriminator line and measure the voltage? You might have a problem with the receiver. 73's -- Bryan Fields 727-409-1194 - Voice 727-214-2508 - Fax http://bryanfields.net
My scope does not really work very well anymore but I'll see if I can get a P-P reading. What value cap should I put on the discriminator line? 73 On Sun, Mar 27, 2016 at 5:08 PM, Bryan Fields <Bryan@bryanfields.net> wrote:
On 3/27/16 5:12 PM, Skyler F wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Does anybody else have experience with hamtronics receivers?
Yes, I have a number of them in place and find they work perfectly with the RTCM. It can give about 2v P-P on the discriminator pin, and has the high frequency compute the RTCM squelch needs.
My prime setup is here: http://gallery.keekles.org/d/28384-2/0330141929a.jpg
Note you'll want to put a cap in line, as the discriminator is DC coupled in the hamtronics. Can you put a scope on the discriminator line and measure the voltage? You might have a problem with the receiver.
73's -- Bryan Fields
727-409-1194 - Voice 727-214-2508 - Fax http://bryanfields.net _______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
I am getting 2v P-P On Sun, Mar 27, 2016 at 5:33 PM, Skyler F <electricity440@gmail.com> wrote:
My scope does not really work very well anymore but I'll see if I can get a P-P reading. What value cap should I put on the discriminator line?
73
On Sun, Mar 27, 2016 at 5:08 PM, Bryan Fields <Bryan@bryanfields.net> wrote:
On 3/27/16 5:12 PM, Skyler F wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Does anybody else have experience with hamtronics receivers?
Yes, I have a number of them in place and find they work perfectly with the RTCM. It can give about 2v P-P on the discriminator pin, and has the high frequency compute the RTCM squelch needs.
My prime setup is here: http://gallery.keekles.org/d/28384-2/0330141929a.jpg
Note you'll want to put a cap in line, as the discriminator is DC coupled in the hamtronics. Can you put a scope on the discriminator line and measure the voltage? You might have a problem with the receiver.
73's -- Bryan Fields
727-409-1194 - Voice 727-214-2508 - Fax http://bryanfields.net _______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
Skyler; 1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step: Then : 2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug. Joe Leikhim On 3/27/2016 7:48 PM, Skyler F wrote:
I am getting 2v P-P
On Sun, Mar 27, 2016 at 5:33 PM, Skyler F <electricity440@gmail.com <mailto:electricity440@gmail.com>> wrote:
My scope does not really work very well anymore but I'll see if I can get a P-P reading. What value cap should I put on the discriminator line?
73
On Sun, Mar 27, 2016 at 5:08 PM, Bryan Fields <Bryan@bryanfields.net <mailto:Bryan@bryanfields.net>> wrote:
On 3/27/16 5:12 PM, Skyler F wrote: > For a voter project, we got the hamtronics VHF receiver pretuned to the > repeaters input frequency. The idea is to use hamtronics receivers for > every voted receive site for equivalent audio characteristics.
> So... I hooked a cheap sound card up to audacity, and took a look at the > spectrum of each receiver. The hamtronics obviously looks like it lacks > high frequency noise on the discriminator output.
> Does anybody else have experience with hamtronics receivers?
Yes, I have a number of them in place and find they work perfectly with the RTCM. It can give about 2v P-P on the discriminator pin, and has the high frequency compute the RTCM squelch needs.
My prime setup is here: http://gallery.keekles.org/d/28384-2/0330141929a.jpg
Note you'll want to put a cap in line, as the discriminator is DC coupled in the hamtronics. Can you put a scope on the discriminator line and measure the voltage? You might have a problem with the receiver.
73's -- Bryan Fields
727-409-1194 <tel:727-409-1194> - Voice 727-214-2508 <tel:727-214-2508> - Fax http://bryanfields.net _______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org <mailto:App_rpt-users@ohnosec.org> http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
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-- Skyler Fennell amsatnet.info <http://amsatnet.info> KDØWHB electricity440@gmail.com <mailto:electricity440@gmail.com>
-- Skyler Fennell amsatnet.info <http://amsatnet.info> KDØWHB electricity440@gmail.com <mailto:electricity440@gmail.com>
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-- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source. You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it. -- Bryan Fields 727-409-1194 - Voice 727-214-2508 - Fax http://bryanfields.net
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency. Given the symptoms, I am putting my money on a misadjusted quad coil. Joe On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug. These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town. WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct. 73 Skyler On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim <rhyolite@leikhim.com> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
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-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone. On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim <rhyolite@leikhim.com <mailto:rhyolite@leikhim.com>> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446 <tel:407-982-0446>
WWW.LEIKHIM.COM <http://WWW.LEIKHIM.COM>
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-- Skyler Fennell amsatnet.info <http://amsatnet.info> KDØWHB electricity440@gmail.com <mailto:electricity440@gmail.com>
-- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
Factory tuned from the factory. And I don't even have a signal generator / counter good for RF. We got one hamtronics board, and won't buy another until we get this one working. On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone.
On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim <rhyolite@leikhim.com> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit <http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users> http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info KDØWHB <electricity440@gmail.com>electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
Sadly you cannot buy harmonics and expect it to work with out a full alignment. It's not the same quality it once was. I've seen many shortcuts and issues with their designs. The ceramic caps in most of the exciter are crap and must be replaced with mica to clear up their server microphonics. You would be best served by getting a basic service monitor. There is simply no good way you'll be able to run a repeater well with out one. :( 73s On March 30, 2016 12:11:06 PM EDT, Skyler F <electricity440@gmail.com> wrote:
Factory tuned from the factory. And I don't even have a signal generator / counter good for RF. We got one hamtronics board, and won't buy another until we get this one working.
On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone.
On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim <rhyolite@leikhim.com> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit <http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users> http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info KDØWHB <electricity440@gmail.com>electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
------------------------------------------------------------------------
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-- Bryan Fields 727-409-1194 http://bryanfields.net
Skyler; Here is a wideband VHF 136-156 MHz radio that will solve your ham club problems for $35 each. If these were UHF I would be buying a bushel full. You will need to get the programming software from Ritron. I think it is free. There are similar models with an enclosure, but for much more $$. See the auction below on E-Bay: Seller dale575 Ritron VHF Transceiver PCA, 136-156MHZ, 5 Watt, Model DTX-142-GCWD-I http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-D... On 3/30/2016 12:11 PM, Skyler F wrote:
Factory tuned from the factory. And I don't even have a signal generator / counter good for RF. We got one hamtronics board, and won't buy another until we get this one working.
On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite@leikhim.com <mailto:rhyolite@leikhim.com>> wrote:
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone.
On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim <rhyolite@leikhim.com <mailto:rhyolite@leikhim.com>> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com <mailto:JLeikhim@Leikhim.com>
407-982-0446 <tel:407-982-0446>
WWW.LEIKHIM.COM <http://WWW.LEIKHIM.COM>
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org <mailto:App_rpt-users@ohnosec.org> http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info <http://amsatnet.info> KDØWHB electricity440@gmail.com <mailto:electricity440@gmail.com>
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com <mailto:JLeikhim@Leikhim.com>
407-982-0446 <tel:407-982-0446>
WWW.LEIKHIM.COM <http://WWW.LEIKHIM.COM>
-- Skyler Fennell amsatnet.info <http://amsatnet.info> KDØWHB electricity440@gmail.com <mailto:electricity440@gmail.com>
-- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
Well stupid me for not listening to you guys. I guess the hamtronics is really sensitive to low impedance outputs, and the highs get cut off if you have any sort of load at all. When I turned on the internal amplifier, the RTCM was happy with calibrating squelch. Can anybody explain to me what "Diode calibration" means? 73, Skyler On Wed, Mar 30, 2016 at 5:42 PM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Skyler;
Here is a wideband VHF 136-156 MHz radio that will solve your ham club problems for $35 each. If these were UHF I would be buying a bushel full. You will need to get the programming software from Ritron. I think it is free.
There are similar models with an enclosure, but for much more $$.
See the auction below on E-Bay:
Seller dale575
Ritron VHF Transceiver PCA, 136-156MHZ, 5 Watt, Model DTX-142-GCWD-I
http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-D...
On 3/30/2016 12:11 PM, Skyler F wrote:
Factory tuned from the factory. And I don't even have a signal generator / counter good for RF. We got one hamtronics board, and won't buy another until we get this one working.
On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone.
On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim < <rhyolite@leikhim.com> rhyolite@leikhim.com> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB <electricity440@gmail.com>electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
"Once you have verified that the firmware is running, place a jumper shunt on JP8 and JP10. Be sure to do this at a reasonable human room temperature (like 60-80 deg. F). This is necessary because this procedure initializes the operating parameters in the EEPROM and also does a *temperature compensation* *diode calibration* which needs to happen at room temperature. Once the jumper shunts have been installed, power-cycle the board and wait for the system activity light to come on steady (about 4 seconds or so after the 5 second initial wait time). Then remove the jumper shunts."
From https://allstarlink.org/votersystem.pdf page 20 Chuck
On Sat, Apr 2, 2016 at 3:23 PM, Skyler F <electricity440@gmail.com> wrote:
Well stupid me for not listening to you guys. I guess the hamtronics is really sensitive to low impedance outputs, and the highs get cut off if you have any sort of load at all. When I turned on the internal amplifier, the RTCM was happy with calibrating squelch.
Can anybody explain to me what "Diode calibration" means?
73, Skyler
On Wed, Mar 30, 2016 at 5:42 PM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Skyler;
Here is a wideband VHF 136-156 MHz radio that will solve your ham club problems for $35 each. If these were UHF I would be buying a bushel full. You will need to get the programming software from Ritron. I think it is free.
There are similar models with an enclosure, but for much more $$.
See the auction below on E-Bay:
Seller dale575
Ritron VHF Transceiver PCA, 136-156MHZ, 5 Watt, Model DTX-142-GCWD-I
http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-D...
On 3/30/2016 12:11 PM, Skyler F wrote:
Factory tuned from the factory. And I don't even have a signal generator / counter good for RF. We got one hamtronics board, and won't buy another until we get this one working.
On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone.
On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim < <rhyolite@leikhim.com> rhyolite@leikhim.com> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB <electricity440@gmail.com>electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
_______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
Just FYI, the RTCM input has 47 PF to ground and is about a 60k ohm load without JP1 and about a 33k ohm load with JP1. The detector chip in the r303 receiver has an output impedance of about 450 ohms and needs to feed the RTCM as directly off pin 9 as possible without any series resistance or any capacitance to ground that might attenuate the high frequency noise that the squelch needs. Don't forget to have a series capacitor to block DC, around 5 or 10 microfarad should be good. Chuck On Sat, Apr 2, 2016 at 4:06 PM, Chuck Henderson < rpt2@chuck.midlandsnetworking.com> wrote:
"Once you have verified that the firmware is running, place a jumper shunt on JP8 and JP10. Be sure to do this at a reasonable human room temperature (like 60-80 deg. F). This is necessary because this procedure initializes the operating parameters in the EEPROM and also does a *temperature compensation* *diode calibration* which needs to happen at room temperature. Once the jumper shunts have been installed, power-cycle the board and wait for the system activity light to come on steady (about 4 seconds or so after the 5 second initial wait time). Then remove the jumper shunts."
From https://allstarlink.org/votersystem.pdf page 20 Chuck
On Sat, Apr 2, 2016 at 3:23 PM, Skyler F <electricity440@gmail.com> wrote:
Well stupid me for not listening to you guys. I guess the hamtronics is really sensitive to low impedance outputs, and the highs get cut off if you have any sort of load at all. When I turned on the internal amplifier, the RTCM was happy with calibrating squelch.
Can anybody explain to me what "Diode calibration" means?
73, Skyler
On Wed, Mar 30, 2016 at 5:42 PM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Skyler;
Here is a wideband VHF 136-156 MHz radio that will solve your ham club problems for $35 each. If these were UHF I would be buying a bushel full. You will need to get the programming software from Ritron. I think it is free.
There are similar models with an enclosure, but for much more $$.
See the auction below on E-Bay:
Seller dale575
Ritron VHF Transceiver PCA, 136-156MHZ, 5 Watt, Model DTX-142-GCWD-I
http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-D...
On 3/30/2016 12:11 PM, Skyler F wrote:
Factory tuned from the factory. And I don't even have a signal generator / counter good for RF. We got one hamtronics board, and won't buy another until we get this one working.
On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite@leikhim.com> wrote:
Were these receivers factory built and tuned or did individual club members build them? Either way, you might try others from the lot. If you have only a rudimentary signal generator and / or frequency counter, perhaps I can walk you through some "field expedient" steps over the phone.
On 3/30/2016 12:01 PM, Skyler F wrote:
I don't have the test equipment to go through all of the dirty Local Oscilator, SINAD, etc., so I will have to wait on that a few weeks before the president of the club gets back in town.
WHEN I bypassed the capacitor and resistor ( 1k and .03µ) , the RTCM was able to calibrate squelch. The LED flashed several times and then was steady. Maybe the capacitor is the wrong value. There was no code on it, but based on the resistor code, the value was correct.
73 Skyler
On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim < <rhyolite@leikhim.com> rhyolite@leikhim.com> wrote:
If you are using an external reference, you cannot make up for the 2nd LO error if it is wildly off. There is an easy SINAD related test in EIA-603 that is called Offset Acceptance Bandwidth that would indicate if the IF were off center. Things that could go wrong apart from simple misalignment of the Quad Detector coil could include the LO crystal being way off frequency, the IF filters being wrong BW or off spec pass frequency.
Given the symptoms, I am putting my money on a misadjusted quad coil.
Joe
On 3/28/2016 5:06 PM, Bryan Fields wrote:
On 3/28/16 2:51 PM, Joe Leikhim wrote:
1) Make sure the receiver First Local Oscillator is adjusted correctly on frequency. (Fo -10.700 MHz) Likewise the second LO should be at around 10.2450 MHz. The second LO is not adjustable, so any minor error would have to be made up with the TCXO U3. After this second step:
Then :
2) Make sure the general alignment is set properly, especially the discriminator coil T2 which responds to 10.7000 MHz from a signal generator, has an S curve response. In my experience with these sort of Quadrature Detector chips, you can get a false sense of IF centering where the noise component is suppressed. You might try adjusting for maximum noise first without the 10.7000 MHz signal. Be careful you don't jam the coil slug.
These are both very good points i didn't consider. I normally don't check my reference oscillators in the hamtronics as they are using an external 10MHz source.
You will want to check SINAD on it as well, if it's not making spec (and those hamtronics are very sensitive), something else is wrong with it.
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
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-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB <electricity440@gmail.com>electricity440@gmail.com
-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
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Hi Bryan, can you send me the exact wiring between your hamtronics and your RTCM? What value DC blocking capacitor, any jumpers in the RTCM selected etc...? 73, Skyler On Sun, Mar 27, 2016 at 5:08 PM, Bryan Fields <Bryan@bryanfields.net> wrote:
On 3/27/16 5:12 PM, Skyler F wrote:
For a voter project, we got the hamtronics VHF receiver pretuned to the repeaters input frequency. The idea is to use hamtronics receivers for every voted receive site for equivalent audio characteristics.
So... I hooked a cheap sound card up to audacity, and took a look at the spectrum of each receiver. The hamtronics obviously looks like it lacks high frequency noise on the discriminator output.
Does anybody else have experience with hamtronics receivers?
Yes, I have a number of them in place and find they work perfectly with the RTCM. It can give about 2v P-P on the discriminator pin, and has the high frequency compute the RTCM squelch needs.
My prime setup is here: http://gallery.keekles.org/d/28384-2/0330141929a.jpg
Note you'll want to put a cap in line, as the discriminator is DC coupled in the hamtronics. Can you put a scope on the discriminator line and measure the voltage? You might have a problem with the receiver.
73's -- Bryan Fields
727-409-1194 - Voice 727-214-2508 - Fax http://bryanfields.net _______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users
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-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
participants (7)
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Bryan Fields -
Bryan Fields
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Chuck Henderson -
Joe Leikhim -
Kirk Just Kirk -
Skyler F -
Tim Sawyer