Harris RF-301 Transceiver Problems

[Jim Simmons]

Dave,
If the problem occurs on all bands - and -
You have the antenna output connected to a dummy load - and -
The tubes all check good - and - the audio sounds good - and -
You have the audio gain control (xmit) at a suitable level - Then -
It sounds very much like an ALC problem.  If the XCVR has been in 
storage for awhile, it may just be corrosion, or dust, on the plug and 
jacks.  Check them on the IF board (P-20) and the PA board (J-24).  
Disconnect and reconnect them several times to wipe the contacts.

The ALC controls the output power of the transmitter, without distorting 
it.  It is developed by rectifying the rf input at the grid of V1 
(6146B).  This rectified (DC) voltage goes back to the IF AMP and 
controls the IF AMP output which goes to the PA AMP input. (Sort of a 
'round robin')

It has been my experience on Harris radios (I used to teach maintenance 
on them) that the majority of problems, such as this, are caused by 
dirty contacts on plugs and jacks.  Not to mention circuit boards that 
are grounded to the chassis by mounting screws.  You might check all 
them also.

If this does not help, then you will have to do some "down-n-dirty" 
troubleshooting with a signal generator and an rf voltmeter.  If you 
need further help, I'll try to be of assistance.

Jim N5MSJ

On 7/31/2010 3:50 PM, David Hollander wrote:
> I have a Harris RF-301 transceiver that has some problems.
>
> The receiver is working fine but the transmitter is only putting out a 
> couple of watts. For a basic check, I have checked the three 6146B's, 
> the 12BY7 driver and the 6DC6 and they are all good.
>
> This has put out full power (near 100 watts) in the past but I have 
> not used it in a few years. Set it up yesterday and the output is 
> barely a couple of watts. The transmit audio is fine when listening on 
> another receiver.
>
> Any suggestions would be much appreciated? I do have the manual. Does 
> anyone know of anyone who works on these radios? This is a very 
> complex radio.
>
> Tnx and 73,
>
> Dave N7RK
>

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