[amsat-bb] Foxtelem and FT-736R

[Tom Worthington]

Thanks Jim
73 and Aloha, Tom, NH6Y

On 10/14/2015 12:04 PM, kb2m at arrl.net wrote:
>   Tom, you're really testing my memory, but I just can't remember the mod
> exactly. I did this mod 15 years ago to a 736 I owned at the time. All I can
> say is it does work at 9k6 when done. I'm sure the mod is out there
> somewhere.
>
> BWTM
>
>   I did find this and I'm 100% sure it's what I did. What a great blast from
> the past. Good luck...
>
>                    ---------------------------
>                         by James Miller G3RUH
>
> These notes tell you where to get FM RX audio direct from the
> discriminator, and where to modulate the FM TX varactor directly.
> These mods are non-destructive and take no more than a few
> minutes.  The signals bypass the "DATA SOCKET" for high grade FM
> operations.
>
> The RX mod is suitable for:
>
>   *  UOSAT-D 9600 baud downlink and terrestrial links
>   *  1200 baud AFSK/FM Standard Packet - BUT IT'S UNSQUELCHED.
>
> The TX mod is suitable for:
>
>   *  FO-20/PACSAT uplink (1200 bps Manchester FM)
>   *  UOSAT-D 9600 baud uplink direct FSK and terrestrial links
>   *  1200 baud AFSK/FM Standard Packet.
>
>                              ---****---
>
>
>
> FT736 -  FM Direct from Discriminator
> -------------------------------------
> Detected FM direct from the receiver discriminator is available
> from the RX UNIT at the junction of R91 and C83.  These
> components are shown in the top right-hand corner of the
> schematic.
>
> Proceed thus:
>   1. Disconnect FT736 from the mains electricity. (Safety).
>   2. Remove top cover only.
>   3. RX Unit is the vertical module on the left.
>   4. Locate R91 which is about 25mm from the top, 50mm from the
> radio rear.
>      the resistor is "on-end", and near a couple of glass diodes.
>   5. Scrape any paint off R91's free end and wet with solder.
>   6. Your RXaudio lead should be a fine screened cable;  connect
>    the inner to R91, and the outer braid to a ground point (e.g.
>    can of TO09)
>   7. Route the cable out though any convenient aperture in the case.
>   8. The discriminator sensitivity (FM Normal) as about 6 kHz/volt.
>
> The link....
>
> ftp://ftp.tapr.org/general/9600baud/96man2x0.txt
>
>
> 73 Jeff kb2m
>
>
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Tom
> Worthington
> Sent: Wednesday, October 14, 2015 14:02 PM
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] Foxtelem and FT-736R
>
> The manual for Foxtelem refers to pulling the discriminator signal out of
> the Yaesu FT-736R for decoding.
> However, it does not suggest a point on the circuit.
> I'm thinking to try between Q20 and Q21 on the RX unit.  perhaps a 0.1 uf
> cap to the collector of Q20?
> Has anybody else tried this?
> Thanks, Tom, NH6Y
>
>