Re: [App_rpt-users] Hamtronics receiver issue with AllStar RTCM
Here is the schematic of the hamtronics output: amsatnet.info/r303out.png Isn't R34 and C44 a lowpass?? On Mon, Mar 28, 2016 at 11:51 AM, Skyler F <electricity440@gmail.com> wrote:
I think normal would be disc., the only other display is deemphasized and CTCSS filtered
On Mon, Mar 28, 2016 at 11:36 AM, Steve Agee <n5zua@earthlink.net> wrote:
For this exercise, audio is either referenced as pre-emphasized (discriminator) or de-emphasized (speaker). So, by "normal" do you mean discriminator?
N5ZUA
On 3/28/2016 12:30 PM, Skyler F wrote:
Actually, the normal audio output is probably what is needed, not de-emph. Again with the 10µF capacitor.
Here is my entire output when I get Normal Audio as good as I can get it. Everything passes except for 3200Hz.
Testing level at 100 Hz for Normal Audio
Testing level at 320 Hz for Normal Audio
Testing level at 500 Hz for Normal Audio
Testing level at 1000 Hz for Normal Audio
Testing level at 2000 Hz for Normal Audio
Testing level at 3200 Hz for Normal Audio
Error -- Measured 10755, should have been between 6929 and 9374
Testing level at 100 Hz for CTCSS Filtered Audio
Error -- Measured 11719, should have been between 100 and 451
Testing level at 320 Hz for CTCSS Filtered Audio
Testing level at 500 Hz for CTCSS Filtered Audio
Testing level at 1000 Hz for CTCSS Filtered Audio
Testing level at 2000 Hz for CTCSS Filtered Audio
Error -- Measured 12326, should have been between 8989 and 12162
Testing level at 3200 Hz for CTCSS Filtered Audio
Error -- Measured 11827, should have been between 6929 and 9374
Testing level at 1000 Hz for De-Emphasized Audio
Error -- Measured 45868, should have been between 9798 and 13257
Testing level at 2000 Hz for De-Emphasized Audio
Error -- Measured 41568, should have been between 4380 and 6155
Testing level at 3200 Hz for De-Emphasized Audio
Error -- Measured 43439, should have been between 2271 and 3073
Testing level at 3200 Hz for Squelch Noise Detector
Error -- Measured 436, should have been between 0 and 50
Testing level at 6000 Hz for Squelch Noise Detector
Testing level at 7200 Hz for Squelch Noise Detector
Error -- Measured 264, should have been between 500 and 1023
On Mon, Mar 28, 2016 at 11:22 AM, Skyler F <electricity440@gmail.com> wrote:
I added a 10µF electrolytic capacitor in series with the Discriminator output of my hamtronics, but was still not able to get the squelch calibrated. Here was the diagnostic output:
Testing level at 1000 Hz for De-Emphasized Audio
Testing level at 2000 Hz for De-Emphasized Audio
Error -- Measured 9581, should have been between 4380 and 6155
Testing level at 3200 Hz for De-Emphasized Audio
Error -- Measured 10030, should have been between 2271 and 3073
Testing level at 3200 Hz for Squelch Noise Detector
Error -- Measured 279, should have been between 0 and 50
Testing level at 6000 Hz for Squelch Noise Detector
Testing level at 7200 Hz for Squelch Noise Detector
Error -- Measured 211, should have been between 500 and 1023
On Sun, Mar 27, 2016 at 10:53 PM, Eric Guth < <eric@efratnetworks.net> eric@efratnetworks.net> wrote:
10 Uf , 35VDC will usually do the job.
73,
Eric Guth
4Z1UG
Allstar: 28422
QSO Today <http://www.qsotoday.com/>
*From:* app_rpt-users-bounces@ohnosec.org [mailto: app_rpt-users-bounces@ohnosec.org] *On Behalf Of *Skyler F *Sent:* Monday, March 28, 2016 7:35 AM *To:* Bryan Fields *Cc:* app_rpt-users@ohnosec.org *Subject:* Re: [App_rpt-users] Hamtronics receiver issue with AllStar RTCM
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> 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
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Skyler Fennell
amsatnet.info
KDØWHB
<electricity440@gmail.com>electricity440@gmail.com
-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
-- Skyler Fennell amsatnet.info KDØWHB <electricity440@gmail.com>electricity440@gmail.com
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-- Skyler Fennell amsatnet.info KDØWHB electricity440@gmail.com
Here is the schematic of the hamtronics output: amsatnet.info/r303out.png
Isn't R34 and C44 a lowpass??
I don't know what to make of your calibration errors as they don't seem to correlate to a HF roll-off problem, but to answer your question, yes, it's an RC low-pass filter, with a -3 dB corner at 2.4 kHz. You might want to replace the 0.033 uF shunt cap with 0.01 uF to flatten out the high end of the audio passband a bit. --- Jeff WN3A --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
Replying to myself...
an RC low-pass filter, with a -3 dB corner at 2.4 kHz
After finding a better scan of the receiver schematic, what I thought was a 2k resistor as R34 is really 1k, so the corner is 4.8 kHz. Based on that, I doubt even more the HF roll-off is the reason your calibration is failing. --- Jeff WN3A --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
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Skyler F