[Boatanchors] BC-342N Xtal Filter, anybody have one?

[Philip Atchley]

Hi Vic et al,
About having used receivers with a single crystal filter and phasing.  Yes,
I've had a number of Hammarlund SP-600's, Hammarlund HQ-180, HQ-170, HQ-145
and there is presently a Hallicrafters SX-71 sitting next to the BC-342.
All with single Xtal filters/phasing.

I understand that the BC-342 is supposed to work a little differently than
other sets with the phasing control, but just don't feel this one is working
"right".   I can adjust it to a spot where everything, and I DO mean
everything is nulled out, but that doesn't seem right either.  Otherwise,
there seems to be NO effect on the overall selectivity that others using
this receiver report.

On another note.  Yes those are nice fat Xtals, not like the thin wafers you
often see in plug in Xtals.

Fresno, you're just down the road from me !  Sure been nice weather lately
8^)

73 from the "Beaconeers Lair".
Phil, KO6BB


> Philip Atchley wrote:
> > Hi All,
> > In troubleshooting why the Xtal phasing in this BC-342 isn't working
> > properly (NO effect on selectivity, ONLY sensitivity)
>
> Have you had experience with a properly working single-crystal filter
> such as is found in the 342 and other receivers of similar vintage?  I'm
> asking because it may be OK.  The characteristics of these filters are
> much different from the crystal lattice filters in use today.  Tune in a
> CW signal or steady carrier to a pitch of about 800 Hz and see if you
> can peak it with the phasing control -- actually, it will not get
> stronger (it will get a little weaker), but other frequencies will drop
> out even more.  By adjusting the phasing capacitor you can null out one
> side of zero beat for single-signal reception...see if you can do this.
>
> > Then I examined the Xtal element under the glass before re-assembling
it.  I
> > was dismayed to see a couple chips in the edges where the side meets the
> > face!
>
> I don't think this is the problem.  These are big fat crystals and a few
>   very small chips won't hurt.
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco