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RE: IFD board and the FT-736R



Hi Bill,
  
Thanks for your follow-up note on your IFD install in the FT736r. You and I
have exchanged email before on this subject. I also am trying (with no luck
so far) to get the IFD to work in my 736. Given that it now seems there are
more than just you and I having problems with this kit, it is time to get
organized. I have several ideas along that line:
  
1. We keep a list of hams you have got the kit, installed it, and record the
results.
2. Develop a standard set of check-out steps, and update it regularly.

I will pick up the ball and create a MS Word 2000 DOC file with the
beginnings of these ideas. Anyone who is interested in contributing is
encouraged to do so. A simple email to me gets you on the list of interested
parties.

My current status is that mine doesn't work. That means no DCD when UO-36 is
overhead and known to be transmitting. My IFD is connected to radio port 2
on a TAPR/Motorola 56002EVM DSP. Per suggestion from Stacey Mills, W4SM, I
moved my IFD to the exact spot shown in the QST article. That didn't help.
When I check the Data Out port with a scope, I do NOT get a normal noise eye
pattern. Instead, I seem to get two parallel noise patterns about .5 volt
apart from one another. When I compare that output to the IFD audio output
port, I see a normal noise pattern. Those two ports are on two different
sides of an opamp, and our assesment at this point is that the gain is way
too high, and extraneous noise is being introduced in the process. There is
also a possibility that the opamp in my unit is simply damaged. I relayed
all of this info to Symek, and they agreed to send me a second unit. I
expect it to arrive by 8/4.
  
As for Roy W0SL comments, I don't think there is any way you could NOT have
a ground return for the IFD and have the 736 perform normally otherwise, as
the shield for the IF in and out is grounded. With that said, I have not
specifically verified that the +5vdc regulator on the IFD is operational, so
I plan on going back and checking it. Neither have I verified the oscillator
operation. All good points.

After hearing your comments, I am not sure that my unit is damaged at all,
and there is a yet-undiscovered problem outstanding. I believe if we
approach this situation in logical fashion, we can either get it resolved or
declare it unfixable. Keep in mind that Stacey W4SM has installed an IFD in
his 736, and he claims it is fully operational. 
  
I will try to have the DOC file created in the next 24-48 hours and you will
be the first to get a copy. Any comments would be greatly appreciated. If
anyone needs it in a format other than MS Word, I will try to accomodate.
  
Regards,
Steve Diggs, W4EPI

-----Original Message-----
From: Bill Hurlock [mailto:bill@hurlock.net]
Sent: Wednesday, July 26, 2000 4:16 PM
To: 'amsat-bb@amsat.org'
Subject: [amsat-bb] IFD board and the FT-736R


Would anyone that has installed a Symek IFD board in there FT-736R
please comment on how the install went and if they found the board to
perform according to the specs that came with the board. I have not had
any luck installing the board and have returned it only to find that
there was no problem found with it when it was checked out at Symek. My
736 is working OK and have no problems with it in normal operation. The
install went as directed. When checking the the data output it is stated
in the doc's that about 2vp-p of noise should be present. I am only
observing about .2vp-p on a TEK scope. The only way I can ever get data
to appear on the data output is by tweaking L44 and than it is very
critical. I have also noted that where the 736 shows the signal is
centered on the demod meter the IFD centers half a meter scale lower for
its center signal. Voltages listed in the doc's do seem to agree closely
with those measured on my board. Other things observed are the RSSI
signal will not come close to the .1volt mentioned in the check out page
in the doc's. When receiving a 38.4 signal I can't see any EYE signal at
all and the percentage showing on WISP is only around 4% if that. I have
been able to get higher %'s on 9.6 which I understand is lower on output
because the IFD is setup for the higher data rates. The comments I have
gotten so far suggest that tuning of the rig and of the IFD itself
aren't that critical. I am connecting to one of the TNC_3S tnc's from
Symek with a 9.6 and a 38.4 modem in it.

WA2TQI Bill

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