[HBR] The long, SLOW HBR project

[Walt Hutchens]

Bill Cromwell

> Now you have me reconsidering all of that. I do have those 3.395 mc filters -
> one SSB and one CW. And I have the 85 kc cans coming. And I have the HR10. And
> I have a spare 9 mc filter (SSB). And oh BTW - a Drake CW filter, too. I
> almost forgot the HW16. I think there is a filter in there, too.
> 
These are parts of several quite different HB receivers.

> I think those HBR coils and their Q are a major factor.
> 
BIG as far as controlling front end overload, a very common problem for
ham sets in those days.   You simply cannot get the Q of a 1-1/4" diameter
coil wound with #22 wire (or whatever is the spec) on a 3/8" or smaller slug
tuned form ... it can't be done.

Using toroids you can get there, but that requires a different approach to
the adjustments.  

> Lack of bandswitch contacts, too. The pins and sockets get a more vigorous
> scrubbing than a little old switch.
> 
This is probably more a matter of some manufacturers using really cheap
switches -- Heath, I'll bet -- that did not age gracefully.   Plenty of
military sets had bandswitches and those that haven't been underwater or
sitting in a leaky barn for 50 years still work well.

> Is a guy allowed to build more than one version of the HBR?
> 
Gosh, I hope so!   Mine is series filament/line HV, uses plate detectors,
has an unusual AGC circuit, and a totally UN-W6TC mechanical layout, but
there are many other worthwhile variants.  The idea of turning an HR-10 into
a W6TC-like HBR is interesting.

Plus there are several 'traditional' designs ...

> If so... where to start? I think the dual conversion setup with the 85 kc
> second I.F.
> 
And that would certainly be one of the top ones in the 'traditional'
department, needing only minor adjustments from the W6TC specifics to
accommodate the slightly different 2nd IF.   (Change the 2nd LO frequency
... a 'tweak,' not really a change.)

It will help a lot if the 1st IF is close to the W6TC design because that'll
mean that the coils can be wound to his specs.   1700 or 1681 kcs ought to
be just about equivalent -- within the range of adjustment of the coils and
trimmers.  Once you go to 3.395 (or more distant) IFs, you'll have to start
pretty much from scratch on the 1st oscillator coils.   A LOT of
work!  

If built carefully, that 1700kcs-85 kcs design should run rings around the
HR-10 and practically all other receivers of the 1960 time period.  Other
people built that variant, so you might get some hints by digging
through the literature.

Walt 
KJ4KV