Problem with SB 301

[Stewart Lyon]

Ron,
Did it ever work? The problem with Heathkits that's not true with other
rigs is that it may have never worked and was abandon. I just went
through a SB-401 that was full of extra jumpers, no jumpers, missing and
bad solder joints. It was obvious the builder gave up. Once I fixed all
that stuff the rig really works good what with all unused tubes, etc.

As to your -301, I'd be suspicious of a mis-wire in the AGC circuit
someplace.  On a SB-301, the calibrator should make about 3-4 Volts AGC
(on 7MHz and at the AGC switch). If it reads much higher (say 20-30
Volts), it may not be controlling the the RFAmp, etc and if lower (>.7
VDC) then the diodes are open. Either way, the RF and IF is running wide
open. You didn't say what the S-meter was reading.  I would go over every
solder joint and harness conection against the build manual, starting on
pg1.  Bet you'll find a wiring error or a bad solder joint.

On the other hand, if it did work and just quit, check the AGC diodes.

73, Stu W6CUX

On Sun, 15 Aug 1999 14:13:54 -0700 Ron Wicker <ronwick at FLASH.NET> writes:
>I am trying to get an SB 301 receiver going.  I started alignment, but
>as I crank up the audio volume, or the signal strength increases, it
goes
>into oscillation.  I have to turn the audio down.  Strong signals seem
to
>overload.  I have been cleaning contacts and resoldering tube and
>component joints.  Any suggestions or comments?
>

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