More for Bernie on SB102

[Kenneth G. Gordon]

On 3 Oct 2006 at 19:37, W5EUQ wrote:

> One thing that concerns me is that Bernie says he's performed the
> alignment fastidiously(spelling?) and feels it has to be something
> else.  This is one may be one of those "dogs" that one gets and has
> real problems finding the problems.

You know, Robert, you are one fine fellow! :-)

I agree with you: I think there is something ELSE wrong. Some 
component has failed, or there is a wiring error that he hasn't yet 
caught, but in any case, it isn't one of the  normal problems we have all 
experienced.

Let me review: 

1) Bernie has good output and sensitivity on all bands EXCEPT 40.

2) On 40, both sensitivity and output are down.

3) He has performed the alignment procedure fastidiously (as you 
correctly spelled it), more than once, and nothing changed.

4) He has checked all tubes and replaced the doubtful ones.

5) His heterodyne oscillator alignment seems to be correct.

6) Wasn't there also some sort of problem with 80? Low output?

Hmmmm....I will study my SB-102 manual and schematic to see if I can 
suggest any course of action to follow.

It IS possible that one or the other of the 40 meter driver/preselector 
coils has been damaged somehow. Perhaps a shorted turn. But it would 
seem to me that this sort of damage would show up in the alignment 
procedure since adjusting the slug wouldn't show a good, sharp peak.

One other thing I think I would do is to carefully check the frequencies 
of both the heterodyne oscillator output, and those around the 6CL6 
driver.

It is also possible that something is operating at 1/2 the correct 
frequency and some OTHER stage is doubling when it should be 
operating straight through.

There also may be a bandswitch wiring error that has gone unnoticed.

Ken Gordon W7EKB

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