[Icom] Mods for ICOM 756 PROII

[Bill Tarkington]

Ray, I am AF MARS, so I think it was your post I read about before doing my
mod.  This caused me to contact my friend Adam Farson and the best Pro2
expert I know of, to inquire about whether he thought I would get the same
results as you considering that my operating frequencies are not in 5-6Mhz
band. Mine are in the 7Mhz and 4-5Mhz bands.  Adam felt it most likely I
would not see your results, so did the mod.  Adam asked that I do some
precise measuring of my power output at 50KHZ increments across both mine
and your bands using a BIRD 43 meter into a 50ohm dummy load. He then would
post those results on his IC 756 Pro 2 Web site which I feel certain you are
aware of. I still have this to do in the near future and as you can see, it
will take a little time.  Fortunately, I have a second rig, a KW 950SDX
which puts out 150W on all bands even after the MARS mod.  However, I wanted
the Pro2 to also be on line since it interfaces with my PW1 Amp, where the
KW has no amp. So, appreciate your original post. Will let you know how the
test measurements come out. Bill/k3yc.
----- Original Message -----
From: "Ray V." <w2ec@attglobal.net>
To: <icom@mailman.qth.net>
Sent: Tuesday, January 21, 2003 3:55 PM
Subject: Re: [Icom] Mods for ICOM 756 PROII


> I can verify the gradual power output degradation between 5.2 and
> 5.999mhz. I made the MARS mod to get to various MARS 5mhz channels in
> that range from near the proposed 60 meter band thru the very high end
> of 5mhz and must say that the 756ProII is NOT a good choice if you
> anticipate wanting to work 60 meters barefoot if it ever becomes
> available to hams. At first I thought it was just my ProII but I have
> had many comments agreeing that it does not provide full output in that
> range and NO comments from anyone who said theirs works fine with full
> output from 5.2 to 5.999. That it has something to do with the bandpass
> filters seems clear because 5.999mhz (into a dummy load of course) has
> barely 10 watts output, but change to 6.000 when the next bandpass
> filter is switched in and power jumps right back to full output.
>
> Fortunately most of my MARS operation on the 5.2-5.999mhz range is
> digital so the low power restriction doesn't seem to be too bad, but on
> SSB nets, I have to go back to my old TS-940S which works just fine in
> that range.
>
> My IC-706MkII also works fine in that range, it's just something Icom
> did to the 756ProII that restricts its power output in the 5.2 to
> 5.999mhz range.
>
> As Bill says, the mod is not for the faint of heart if you can't handle
>   unsoldering SMT component diodes about the size of the head of a pin.
>
> 73, Ray  W2EC
>
> Bill Tarkington wrote:
>
> > Hi Ken:  I too own the Pro2. Only mod I am aware of is the MARS mod for
both
> > US and European units. This mod calls for the removal of specified
diodes to
> > open up the transmit of the Pro2.  It is already wide open for Rx, but
not
> > -----------snip----------
>
>
>
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