[1000mp] Noise on Carrier

Fri, 13 Feb 2004 13:36:11 -0500

The FP-29 for the Mark V is a PWM (Switching) supply, and the output
voltage is switching at approximately 55Khz (depending on load), before
rectification, so I don't think that it would sound like you described if
there
was a little leakage in the output filter caps.  In fact there are only 3 -
1,200uf/50V
caps in parallel and a filter inductor on the output since there isn't much
to filter with ripple that high in frequency.  I've had the pleasure to
repair a number
of FP-29's so far, and hopefully you will find a simpler solution such as
Steve
mentioned.  Good luck.

73,
Ed
W2UV

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Steve
Sent: Friday, February 13, 2004 1:09 PM
To: [email protected]
Subject: RE: [1000mp] Noise on Carrier

Before you assume that this is a power supply problem eliminate the
possibility of a ground loop. disconnect all the accessories from the radio
and connect it to a dummy load. Then listen to it with a highly attenuated
second receiver. If you still hear the noise it's probably the power supply.
If not try reconnecting one accessory at a time until you find the source of
the problem.

Steve .. AI7W

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Winston Rogers
Sent: Friday, February 13, 2004 00:55
To: [email protected]
Subject: [1000mp] Noise on Carrier

While monitoring my Mark V CW signal today with a highly attenuated second
receiver I noted some fuzz (probably AC) ripple on my carrier.  It is not
terrible but noticeable at slow speeds and with lower frequency tones, and
more obvious when key down. I asked a friend to check me, and he confirmed
it was there..  I suspect a filter cap in the power supply leaking a little.

Anyone have comments or a like experience?  No, a key click mod has not yet
been installed.

Win W0LZ

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