[Hammarlund] SP-600 RF illness

[Cecil Acuff]

Hi Craig,

        Did you do the cap replacement or was it done by a previous owner?

I agree with you, you probably have a resistor opened up below the RF deck.

The reason for the question....if you did the cap replacement and haven't
entered the RF deck you didn't finish...there are several black beauties in
the RF deck....it's also possible that if a previous owner did the cap
replacement he may not have entered the RF deck either.  Anyway there are a
couple of good reasons to go into that section now.  There are no other ways
to access the tube sockets.

You may already know the following but thought I'd mention it:

Some key points when removing the RF deck.   Make sure you place the turret
(band switch) between two detented positions before removing the RF
deck...failure to do so will render damage to parts you can't buy anymore!!

Find a way to mark all the wiring that has to be removed before you start.
You'll need to know where all that goes and it gets confusing.  Have a plan!

If you have some tube extenders you can make some voltage measurements or
you can probe the sockets and take some resistance measurements and compare
them to the manual.  Probably will give you a good idea of what to expect
before going in.

Hope all goes well!

Cecil....


----- Original Message ----- 
From: "Craig Roberts" <crgrbrts at verizon.net>
To: <hammarlund at mailman.qth.net>
Sent: Wednesday, September 08, 2004 12:47 PM
Subject: [Hammarlund] SP-600 RF illness


> Hmmmm.  Something's amiss in my SP-600 RF amp section. The radio's
> sensitivity has suddenly dropped to near zero.  The only audible signals
> are from nearby AM broadcast stations. I've built "foxhole radios" with
> a Gillette Blue Blade and a chunk of pencil lead that have worked about
> as well.
>
> All my Hammarlund's Black Beauties have been replaced. All tubes are new
> and check out okay.  Pulling RF amp tube V1, an action that used to
> decrease sensitivity, now increases it very slightly. I suspect a
> resistor may have opened up under this tube. My question is, must I now
> pull the RF deck out completely to service this area or is there a
> simpler way to access the tubes' sockets?  I know I should probably buy
> Chuck Rippel's SP-600 video from Floyd Soo, but launching a new antenna
> business has tied up all but $3.74 of my ready cash right now.
>
> Your advice is greatly appreciated.
>
> 73,
>
> Craig Roberts
> W3CRR
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