[ICOM] 751A Transmit

[Jim Miller]

"with a very light sand paper "

WOW, seems VERY harsh.  How about just pencil eraser (and not the ink kind).
We had to do that "in the old days"(1968) on some of the equipment that
customers had placed in factory environments etc. (humid, DIRTY, corrosives
in the air).

73, Jim

----- Original Message ----- 
From: "GGLL" <nagato at arnet.com.ar>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Tuesday, July 24, 2007 7:55 AM
Subject: Re: [ICOM] 751A Transmit


Perhaps a general readjustment of screws is in order (for boards,
specially RF and power amplifier). Unscrew them a little then re-tight.
In extreme cases, someone add star washers also.
For the connectors, unplug and sand the pins (exposed ones) with a very
light sand paper then plug and unplug a couple of times the connector.
Check antenna connector tightness also.

Best regards
Guillermo - LU8EYW.

EP Swynar escribió:
> Good Day All,
>
> My venerable 751A put up some very strange behaviour yesterday, after
having sat idle for some 3 months...I wonder if anyone reading this might
have a suggestion, or two, before I open the rig up later this afternoon?
Any & all feedback / comments are not only welcomed, they're hereby being
solicited! Hi Hi
>
> Specifically, I fired up the rig to transmit on 40-meters and the power
output meter showed nearly 150-watts! I reduced the drive control COMPLETELY
counterclockwise, & it STILL put out the same power...
>
> The carrier would stay continuously "on", too, dropping off ONLY when the
VOX did.
>
> This strange condition was evident on both a dummy load, as well as a
resonant antenna. All "peripherals" were removed, the grounding was
checked --- status unchanged. I tried it on different bands, but the only
difference was the power output, which varied from 100- to 150-watts
(dependent upon the band).
>
> Finally, I tried 10-meters & the output suddenly dropped right off to
zero --- I'm sure I popped the internal fuse with that last test.
>
> It would appear that the finals in the rig are somehow "taking off" /
self-oscillating, for some reason. I have not touched the rig in any way,
shape, or form, since QRN took over 160-meters here last April.
>
> I wonder if, by sitting idle like that, one of the interior connectors has
somehow oxidized / deteriorated in the humidity of summer...?
>
> In any event, I have to get inside to replace the fuse anyway, so I'll
check those out...but I am curious if anyone else has ever had any similar
such occurance with their 751A...
>
> Thanks in advance, & vy
>
> ~73~ Eddy VE3CUI - VE3XZ
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>
----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/