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