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[Yaesu] FT 560 S meter question

To: <yaesu@contesting.com>
Subject: [Yaesu] FT 560 S meter question
From: dgf@netcom.com (David Feldman)
Date: Tue, 19 May 1998 15:09:48 -0700 (PDT)
I'm resurrecting an old FT 560 transceiver. Things are going well, but
the main S meter itself seems to be dead. I've got a 1 mA meter in the
circuit and it is showing received signal strength and transmit plate
current (the relative output indication circuit seems to be dead).

Anyway, I'm having some trouble understanding the S meter circuit -
at a no-signal condition with RF gain control max, current thru the
meter is about 1mA (full deflection on the temporary meter I have here).
With a strong receive signal or decrease in RF gain control, meter
deflection decreases. So I'm wondering if the meter in the transceiver
is really a "backwards reading" meter?

The thing that confuses me the most is that during transmit, the circuit
diagram implies that the meter should read cathode current, increasing
the mA thru the meter as the cathode current increases. This is what I
observe. Therefore, in transmit, the meter doesn't seem to be backwards

Does anyone have some experience with this rig that could shed some
light on what I'm finding? Or best possible case, does someone have
a panel meter from this rig or a compatible rig they would like to
part with?

Also, is there some trick to transmitting a CW carrier? When I hit
the key I get a sidetone and can get the TX relay to trip (adjusting
the back-panel relay control and the front panel vox gain control
til this works), however, I can't get a carrier out. I can get a transmit
signal out on SSB, but I'm not sure how the CW transmit mode is supposed
to work. 

I'm working from a schematic but no other documentation.

73 Dave WB0GAZ dgf@netcom.com

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