[ICOM] 756 PRO Question

[William Shadid]

Mac,

I have had the same problem in the past with my IC-756PRO-II and an older
FT-1000MP, but it is not the radio. The SB-200 seems to have a problem with
the input pi-net circuit being out of alignment as a result of aging -- that
is, the input no longer presents a 50 ohm load to the exciter.

There is at least one web site showing some modifications to that input
circuit to make it perform better. Do a search on "Heathkit SB-200" and I
think you will find it. Mine works fine now --  but I just retuned the
inductors in the input circuit for minimum SWR on the exciter side. The
suggested modifications have you changing the capacitor values on the pi-net
circuit as well. I cannot get my input circuit to present 1:1 SWR, but I do
get it to the point where the exciter adequately drives the SB-200 without
using the internal antenna tuner.

73,

-Bill, WA9MXQ

----- Original Message ----- 
From: "David S. McCallum" <w7sac at juno.com>
To: <icom at mailman.qth.net>
Sent: Monday, 19 July 2004 12:10 PM
Subject: [ICOM] 756 PRO Question


> Hope this goes through OK. I had my SB200 connected to my PRO and it
> worked great on 10,15, and 20m BUT, when tried I 40m it wouldn't work.
> Checked everything I could think of and even changed the antenna switch
> settings from auto to manual to off and it still wouldn't tune up. I
> don't have a 75m antenna that I could hock up and check that band. A
> friend brought over his solid state amp and it wouldn't key up either.
> I'm using the W3ENY amp keyer cable interface. ANY IDEAS GANG, Mac
> ----
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