[Drake] TR4C 80m hum

[W4AWM@aol.com]

<<on 80m, the receive works fine but transmit has a 
very pronounced line-frequency hum in all modes (CW, AM, LSB, USB)>>


Hi Paul,

A good thing to check for since the problem is only on 80 would be that you 
have a good ground and low SWR.  It is also possible that RF could be entering 
the rig through a resonating mic cable or key line.  Easiest way to determine 
this, since it is an all mode problem, is to disconnect both cables and try 
keying with a dummy plug inserted in the ksy jack, if a kay is needed in the 
tune position.

Also, are you determining that there is hum by monitoring in a local receiver 
or are you getting reports from another station?  RF can easily overload a 
local receiver and cause you to believe that you have all kinds of problems than 
don't really exist! I had a problem like that when I was hooking up the 
PSK-31 interface and tore the shack completely apart before finding that the 
problem was the receiver!  (Red face!)

Hope you find the problem and please post your findings to the list so that 
all may benefit from your experience.

73,

John,  W4AWM


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