[amsat-bb] Foxtelem and FT-736R
worth at maui.net
Thu Oct 15 00:21:16 UTC 2015
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
> 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
> 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
> 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....
> 73 Jeff kb2m
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Tom
> 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
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