I had same problem with FT-101 would tune up to 100 watts out, and almost
immediately
the output would drop 25 watts. Turned out to be 12by7 driver tube.
Marv
-------Original Message-------
From: yaesu@contesting.com
Date: Friday, April 09, 2004 11:03:07 AM
To: yaesu@contesting.com
Subject: Yaesu Digest, Vol 16, Issue 3
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Today's Topics:
1. Low output on FT902 (Jon Klinkhamer)
----------------------------------------------------------------------
Date: Fri, 9 Apr 2004 10:57:37 -0400 (GMT-04:00)
From: Jon Klinkhamer <jonklinkhamer@earthlink.net>
To: yaesu@contesting.com
Subject: [Yaesu] Low output on FT902
Message-ID: <2190943.1081522657177.JavaMail.root@statler.psp.pas.earthlink
net>
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Reply-To: Jon Klinkhamer <jonklinkhamer@earthlink.net>
Message: 1
I=E2=80=99m replacing all my tubes (6146B=E2=80=99s and 12by7) with new one=
s. Using 6146W=E2=80=99s for the finals. The reason is I=E2=80=99m seeing =
low output. The output is maybe 80 Watts at the low bands to just barely hi=
tting 100Watts at the high bands. I neutralized the finals as best I can an=
d aligned the Tx drivers without any noticeable changes. But the thing I al=
so noticed was that during my 10 second tune up, my wattmeter would show th=
at my power was drifting downward by about 10 watts or so. My thinking is t=
hat maybe one of those big old caps is not holding the charge. I suppose th=
e electrolytic dries up after 20 or so years. Does anyone have any comment=
s on this before I start to replace components? One thing I=E2=80=99m going=
to do is check the bias voltages on the tube sockets and make sure they
ar=
e within the noted voltages in the service manual.=20
=20
Thanks for reading,
Jon
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