[Hallicrafters] S-76 antenna trimmer modification

[Mike Everette]

I think the antenna trimmer mod was in QST some time
in the mid 50s.  I have seen it in an old issue either
in a library or on a table at a hamfest; not sure if I
actually have a copy though.  Look in the annual
indexes which appear in the December issues.  It would
most likely be listed under Receivers, Receiving,
Technical Topics, or maybe Hints and Kinks.

It looked like it would be an easy mod.  All it
involved, if I remember the article right (I did look
at it as I too have a 76, actually 2 of them but
neither have the mod), was drilling a hole in the
front panel for the control shaft bushing, and
mounting a small trimmer cap atop the tuning gang,
running a shaft to the panel -- and this required
using a couple of flexible couplings because the shaft
was not a staight shot from the panel to the trimmer
cap -- and opening up the alignment trimmers on the RF
stage.  

Unfortunately I do not recall the value of the added
capacitor.  It was probably no more than 75 pf.  Look
at the schematic and see what the values are for the
alignment trimmers on coils for the RF stage and use
the same value as the highest-value one; it should
work fine.  The antenna trimmer will function on all
four bands.

73

Mike
WA4DLF





 
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