[HBR] One more quick question - HR10

[Walt Hutchens]

Bill Cromwell said:

> I am going to use my HR-10 (not)B as the foundation for
> my HBR. I am going to remove the xtal filter and do the dual conversion
> with the 85 kc cans from the BC-453 type receiver (I have the cans). I
> will be looking for another set of IF cans for the HR-10 to use with the
> xtal filter and then I will be able to build *two* HBRs! The second will
> go on the stripped down chassis I have from a Knight Star Roamer.

I probably should not even offer suggestions about the direction of another
HBR-er's project:  I'm the guy who just spent the last five years or so
learning how to build a decent series string ham receiver, right?   (And for
my next trick, maybe I'll do something REALLY useful, like sketch the
circuit diagram on the head of a pin?)

But ... the great advantage of the HR-10 is that it is close to all the
basic parts for an HBR project, all compatible, and all there in one package
without a bunch of gritty metalwork and force-fitting.   The scheme above
keeps the dial and tuning cap but pretty much recreates all the other hard
parts of HBR construction.   In particular there's going to be a space issue
with those command set IF cans:  The usual plan uses four of them, plus two
IF stages and a second mixer so that's three tubes and four IFTs to be added
with at most two tubes, two (miniature) IFTs, and the crystals subtracted.
I don't have the receiver in front of me now, but I'm thinking 'maybe ...
but it'll likely need a cutout and plate so you can squeeze things
properly.'

(I've no idea what the difference between an HR-10 and a 10B is, but it is
slight.)

Resale value of an HR-10?   As a complete unbuilt kit, $500-up.   (Yeah
really ... personally I don't get it, but people collect the darndest
things.)   As a good original non-smoker working radio, perfect exterior,
maybe $100-$125?  'I don't know what this is, it lights up, probably just
needs a couple of tubes,' with non-original knobs $50 +/- a bit.   Those are
eBay prices; at a hamfest they'd be less.

(I expect we all know how to translate 'probably just needs a couple of
tubes.'  The phrase means 'you are going to spend a week finding all the bad
connections, frozen-solid controls, and other oddball problems in this
sucker ...')

These are not your father's Collins 51S for resale value.

The Knight Star Roamer is the next step down from the HR-10 and at $37.35,
just about half the price.   It's a contemporary, but only four tubes
(6BE6-6HR6-12AX7-6AK6 plus a selenium rectifier and solid state diodes in
the detector/AVC jobs) and pretty much along the lines of the S-38 and
similar sets.   There's an overview, here:

http://www.ohio.edu/people/postr/bapix/StarRmr.htm

I'd say this set was a better match to its intended market than the HR-10
was to its.   It's a very limited set, but at the price, probably okay for
the beginning SWL who might someday get interested in a ham license.
There's no sign of a BFO, so by 1970 it would have been obsolete.

I haven't looked at a diagram but with that description it'll have a
two-gang capacitor (not suited to an HBR) and no sharp filter in the IF.
Also, that transformer probably will NOT handle 6-9 tubes -- it has perhaps
1/3 the filament power and half the plate power needed.   As you imply, a
separate power supply would be required.

Thinking of the Star Roamer as project foundation might better start down a
notch from the HBRs.   Maybe something along the lines of the Simple-X
Super?  With a very high Q antenna coil (and very loose coupling to the
antenna) you might get an interesting set.   If using a separate power
supply then perhaps a beam mixer (with separate oscillator) and mechanical
filter?   That would be a very poor man's Miser's Dream.   Might not have
enough gain for a mechanical filter though.

I'd say do the HBR first.  That ground has been well plowed; lots of people
know what works and what doesn't.  My pipe dreams (in the previous
paragraph) might be no more than that.

Walt 
KJ4KV