[Boatanchors] IT SINGS THE OLDIES!

[Todd, KA1KAQ]

Congrats, Phil - another successful resurrection to your credit.

When you get done there, swing over to VT. I have about 50 projects
awaiting completion.

~ Todd/'Boomer'  KA1KAQ

On 7/14/05, Philip Atchley <beaconeer at sbcglobal.net> wrote:
> Hi All,
> 
> Remember that SP-600 that arrived here, literally a basket case, with a
> totally stripped chassis, tube sockets and IF cans in baggies etc, along with
> my intent to rebuild it from scratch?
> 
> Well, today it got to the preliminary testing stage.
> 
> Today, after quickly buzzing it out to make sure there weren't any B+ shorts
> or anything, I got brave and applied power.  First without the 5R4 rectifier
> in place (to check bias and filaments etc).
> 
> All ok there, so I plugged the 5R4 in, put an antenna on it and checked around
> the BCB.  Alas, no stations, but no smoke either ;-)  I tested the audio
> section for buzz when I touched the volume control with a test lead, that was
> ok! Not even normal IF background noise though, indicating either the detector
> or an IF stage was dead.  I connected a lead to the 455KC output on the other
> SP-600 figuring I'd use it as a signal source, starting at the detector and
> working my way back.
> 
> I heard it at the detector, so kept moving back through the circuit, I could
> poke the signal all the way through the IF strip, but couldn't determine if
> the stages had any real gain (it doesn't yet have an "S" meter installed).
> 
> Then I thought, hmm. . .  Perhaps the signal from the good SP-600 IF output
> was
> just too strong.  So, I turned it's RF gain down, the volume all the way up,
> and then turned the RF gain up just barely enough to hear a weak signal in the
> speaker.  Again I went through the IF strip, this time as I went back a stage
> I could hear the differences in level.  I peaked each stage as I went, most
> were way out.  When I got finished I removed the test signal, and Voila!  I
> had RF noise!  Putting an antenna on the radio it came to life with signals
> all across the BCB.  The selectivity switch worked as expected.
> 
> Right now I have it over on the other side of the room playing the oldies
> station through a headset, just to burn it in awhile.  I think the AGC section
> needs more work as AGC voltage seems a little lower than I think it should be.
> That could be a bad tube or other component (or a wrong wire somewhere), or
> something else dragging the gain down, but all tubes were tested prior to
> installing them.
> 
> But at least there is life in the old carcass, and I'll bet that is the first
> time in many, 'many' years that any electrons have flowed through any of those
> parts
> too!  ALL resistors, paper caps, lytics etc are new.
> 
> 
> 73 de Phil,  KO6BB
> 991 Different NDB's heard to date.
> SWL QSL GALLERY: http://photobucket.com/albums/y123/KO6BB/
> THE BEACONEER'S LAIR:    http://www.geocities.com/ko6bb/
> Merced, Central California, 37.3N  120.48W  CM97sh
> 
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