<div dir="ltr">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.<div>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. </div><div>Chuck <br><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Apr 2, 2016 at 4:06 PM, Chuck Henderson <span dir="ltr"><<a href="mailto:rpt2@chuck.midlandsnetworking.com" target="_blank">rpt2@chuck.midlandsnetworking.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>"Once you have verified that the firmware is running, place a jumper shunt on JP8 and JP10. Be sure to</div><div>do this at a reasonable human room temperature (like 60-80 deg. F). This is necessary because this</div><div>procedure initializes the operating parameters in the EEPROM and also does a <b>temperature compensation</b></div><div><b>diode calibration</b> which needs to happen at room temperature. Once the jumper shunts</div><div>have been installed, power-cycle the board and wait for the system activity light to come on steady</div><div>(about 4 seconds or so after the 5 second initial wait time). Then remove the jumper shunts."</div><div><br></div><div>From <a href="https://allstarlink.org/votersystem.pdf" target="_blank">https://allstarlink.org/votersystem.pdf</a> page 20</div><span class="HOEnZb"><font color="#888888"><div>Chuck</div><div><br></div></font></span></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Apr 2, 2016 at 3:23 PM, Skyler F <span dir="ltr"><<a href="mailto:electricity440@gmail.com" target="_blank">electricity440@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">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. <div><br>Can anybody explain to me what "Diode calibration" means?</div><div><br></div><div>73,<br>Skyler</div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Mar 30, 2016 at 5:42 PM, Joe Leikhim <span dir="ltr"><<a href="mailto:rhyolite@leikhim.com" target="_blank">rhyolite@leikhim.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Skyler;<br>
<br>
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.<br>
<br>
There are similar models with an enclosure, but for much more $$.<br>
<br>
See the auction below on E-Bay: <br>
<br>
Seller dale575<br>
<br>
Ritron VHF Transceiver PCA, 136-156MHZ, 5 Watt, Model DTX-142-GCWD-I<br>
<br>
<a href="http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-DTX-142-GCWD-I/191557457767?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D35389%26meid%3D4bbbffc700cc4aefba654c3ce0d394f8%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D401085025343" target="_blank">http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-DTX-142-GCWD-I/191557457767?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D35389%26meid%3D4bbbffc700cc4aefba654c3ce0d394f8%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D401085025343</a><div><div><br>
<br>
<br>
<div>On 3/30/2016 12:11 PM, Skyler F wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">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.</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Mar 30, 2016 at 10:08 AM, Joe
Leikhim <span dir="ltr"><<a href="mailto:rhyolite@leikhim.com" target="_blank">rhyolite@leikhim.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"> 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.
<div>
<div><br>
<br>
<div>On 3/30/2016 12:01 PM, Skyler F wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">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.
<div><br>
</div>
<div>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. </div>
<div><br>
</div>
<div>73</div>
<div>Skyler</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Mar 28, 2016 at
4:08 PM, Joe Leikhim <span dir="ltr"><<a href="mailto:rhyolite@leikhim.com" target="_blank"></a><a href="mailto:rhyolite@leikhim.com" target="_blank">rhyolite@leikhim.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">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.<br>
<br>
Given the symptoms, I am putting my money on a
misadjusted quad coil.<span><font color="#888888"><br>
<br>
Joe</font></span><span><br>
<br>
On 3/28/2016 5:06 PM, Bryan Fields wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> On 3/28/16
2:51 PM, Joe Leikhim wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> 1) Make
sure the receiver First Local Oscillator
is adjusted correctly<br>
on frequency. (Fo -10.700 MHz) Likewise
the second LO should be at<br>
around 10.2450 MHz. The second LO is not
adjustable, so any minor error<br>
would have to be made up with the TCXO
U3. After this second step:<br>
<br>
Then :<br>
<br>
2) Make sure the general alignment is
set properly, especially the<br>
discriminator coil T2 which responds to
10.7000 MHz from a signal<br>
generator, has an S curve response. In
my experience with these sort of<br>
Quadrature Detector chips, you can get
a false sense of IF centering<br>
where the noise component is suppressed.
You might try adjusting for<br>
maximum noise first without the 10.7000
MHz signal. Be careful you don't<br>
jam the coil slug.<br>
</blockquote>
These are both very good points i didn't
consider. I normally don't check my<br>
reference oscillators in the hamtronics as
they are using an external 10MHz<br>
source.<br>
<br>
You will want to check SINAD on it as
well, if it's not making spec (and those<br>
hamtronics are very sensitive), something
else is wrong with it.<br>
<br>
</blockquote>
<br>
-- <br>
</span><span> Joe Leikhim<br>
<br>
<br>
Leikhim and Associates<br>
<br>
Communications Consultants<br>
<br>
Oviedo, Florida<br>
<br>
<a href="mailto:JLeikhim@Leikhim.com" target="_blank">JLeikhim@Leikhim.com</a><br>
<br>
<a href="tel:407-982-0446" value="+14079820446" target="_blank">407-982-0446</a><br>
<br>
<a href="http://WWW.LEIKHIM.COM" rel="noreferrer" target="_blank">WWW.LEIKHIM.COM</a><br>
<br>
</span>
<div>
<div>
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<div dir="ltr"><font color="#38761d" face="arial
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<pre cols="72">--
Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
<a href="mailto:JLeikhim@Leikhim.com" target="_blank">JLeikhim@Leikhim.com</a>
<a href="tel:407-982-0446" value="+14079820446" target="_blank">407-982-0446</a>
<a href="http://WWW.LEIKHIM.COM" target="_blank">WWW.LEIKHIM.COM</a></pre>
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<div>
<div dir="ltr"><font color="#38761d" face="arial narrow,
sans-serif">Skyler Fennell</font>
<div><font color="#38761d" face="arial narrow, sans-serif"><a href="http://amsatnet.info" target="_blank">amsatnet.info</a></font></div>
<div><font color="#38761d" face="arial narrow, sans-serif">KDØWHB</font></div>
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<pre cols="72">--
Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
<a href="mailto:JLeikhim@Leikhim.com" target="_blank">JLeikhim@Leikhim.com</a>
<a href="tel:407-982-0446" value="+14079820446" target="_blank">407-982-0446</a>
<a href="http://WWW.LEIKHIM.COM" target="_blank">WWW.LEIKHIM.COM</a></pre>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><div><div dir="ltr"><font face="arial narrow, sans-serif" color="#38761d">Skyler Fennell</font><div><font face="arial narrow, sans-serif" color="#38761d"><a href="http://amsatnet.info" target="_blank">amsatnet.info</a></font></div><div><font face="arial narrow, sans-serif" color="#38761d">KDØWHB</font></div><div><font face="arial narrow, sans-serif" color="#38761d"><a href="mailto:electricity440@gmail.com" target="_blank">electricity440@gmail.com</a></font></div></div></div>
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