[Hallicrafters] Poor BCB sensitivty on SX-71

[Barry Hauser]

Phil wrote:

> Now that the SX-71 is in full use I've noticed that the sensitivity 
> on the BCB seems to be very poor, especially compared to the other
bands.  

I noticed the same thing on mine.  It didn't get the intense tweaking
you've done, but the previous owner said he had aligned it.  BCB lacks
punch.  The rest of the bands are very sensitive.

Did you check out the schematics?  Any extra switching on the bandspread
-- or "asymmetry" -- as in a jumper bypassing the RF stage?  Or switching
in a resistor or some small sandbag circuit?  As with the riceboxes --
and portables with separate front ends & loopsticks for AM BCB -- there
may have been a need to prevent overloading.  (a feature I neglected to
list yesterday). 

Somebody told me otherwise, but I also get the feeling that there are
some communications rx's that need a  lot of wire on BCB, more so than
others.  Many multiband radios switch in a loopstick, unique to the BCB. 
Most "regular" communications rx's don't have those, leaving the
resonance factor totally up to the owner.

Barry

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