[App_rpt-users] Hamtronics receiver issue with AllStar RTCM

[Joe Leikhim]

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 at gmail.com 
> <mailto:electricity440 at 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 at bryanfields.net <mailto:Bryan at 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
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>
>
>
>     -- 
>     Skyler Fennell
>     amsatnet.info <http://amsatnet.info>
>     KDØWHB
>     electricity440 at gmail.com <mailto:electricity440 at gmail.com>
>
>
>
>
> -- 
> Skyler Fennell
> amsatnet.info <http://amsatnet.info>
> KDØWHB
> electricity440 at gmail.com <mailto:electricity440 at gmail.com>
>
>
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-- 
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

JLeikhim at Leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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