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Re: Anyone FT-847 and 56002EVM/RI?



Mike, N1JEZ writes:

> > You'll find that the stock TAPR DSP56002EVM/RI doesn't quite have enough
>  > output drive to get 3 KHz deviation at 9k6. 1k2 transmit is fine as is
>  > receive at both speeds. On my EVM/RI I removed/jumpered the 1K output 
pot 
>  > for radio #1. I'm using Doug Braun's 9k6 code and have set my 9k6 modem 
as
>  > follows for transmit:

In a message dated 2/16/00 12:50:59 AM Eastern Standard Time, 
jono@enteract.com replies:

>  If you don't get enough drive just set the radio to 1200 baud and feed it
>  like normal.  The only difference between the two settings is on the input.
>  The 9600 side has a couple buffer amps that the 1200 side doesn't.  Both
>  modulate the varactor in the VCO.    Take your data out thru the 9600 data
>  out line (data is sent to BOTH RXD pins (1200 & 9600) on the output
>  regardless of internal settings).

Excellent tip Jon!  I recently received my FT-847 Service Manual and saw the 
buffer amp you refer to in the transmit line. I was going to modify the 
feedback resistor for 9k6 to increase gain. I hadn't thought about checking 
that 9k6 and 1k2 receive data was available simultaneously......

I never liked running the EVM/RI with as high an output as I was. Time to get 
the Service Monitor out and reset deviation.

73,
Mike, N1JEZ
AMSAT #29649
Local Area Coordinator
"A closed mouth gathers no feet."
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