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Re: AO40rcv Doppler Compensation????

Hello Ken,

I had the same problem!
All what you need is to inverse the MIC control signal.

You can do it with 2 additional resistors in MIC up and
MIC down control with a little modification of the cirquit:

1. connect the collector from 2N2222 over a 20k Resistor
   with pin2 of the MIC Socket (+Voltage from the FT-736)
2. connet the emitter from 2N2222 over a 100k resistor with

Now the emitter from 2N222 has a "pull up" voltage signal
what you can connect with pin1 (step up) from the MIC socket.
for step up signal.

You have to do the same modification for the step down signal!

This modification runns well since more weeks with my FT-736

73´s de
Robert, DD4YR

Ken Dailey schrieb:

> Help! (:-)
> I'm trying to get AO-40rcv's doppler compensation system working with my
> FT736R, so that I can leave it happily chugging away grabbing AO-40
> telemetry.  Sadly I'm not getting anywhere very fast, and wonder if
> anyone out there has managed to get this combination to work, and if so,
> how?
> >From the 'Rig Frequency Control Page' (in AO40rcv) If I select 'COM1,'
> 'Manual Rate Control,' and 'Use RTS/DTR' and then monitor the RTS and
> DTR lines whilst manually selecting positive and negative doppler
> correction I get:
> RTS - Goes from -10V (approx) to -5V (approx) when negative doppler
> correction applied.
> DTR - Goes from -10V (approx) to -5V (approx) when positive doppler
> correction applied.
> (I would have thought that either line should go to +10V when active?)
> My initial thought was to use the RTS/DTR lines and connect to the
> FT736R's mic click (up/down) connections.  However, looking at the RS232
> to TTL level converter that Moe includes in the AO-40rcv's help notes
> for Mic Click working, it would appear to pull the up or down
> connections to ground, which won't work with the FT736R which need's
> either pin 1 or pin 3 of the mic connection connection to pin 2 to go
> either up or down in frequency. (Any interface suggestions?)
> So, is it possible to use Pin 3 on the COM port (TXData) into the CAT
> connection on the back of the FT736R? (Assuming you have a level
> converter again).  However, I have no idea what the ASCII 'UP' and 'DN'
> commands are for an FT736R - the User Guide is pretty useless in this
> respect.  I've tried connecting the computer to the CAT port using Moe's
> suggested interface, with no success.
> Can anyone offer any suggestions to this poor confused sole? (:-)
> 73's
> Ken, G0RVH
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