[HBR] Re: BC-453 IF Transformers

[Dan Merz]

Hi,  correct NC-270/190 i.f. to 230 khz,  my memory needed refreshing.  The
SX 100 and 96 have 50 khz final i.f.'s.  Given a choice,  I favor the
Hallicrafter's.  But the NC's are more the size of an HBR.  Dan.

-----Original Message-----
From: hbr-bounces at mailman.qth.net [mailto:hbr-bounces at mailman.qth.net] On
Behalf Of Dan Merz
Sent: Sunday, January 08, 2006 10:32 AM
To: 'HBR Receiver List'
Subject: RE: [HBR] Re: BC-453 IF Transformers

Hi,   the top hat on the 85 kc i.f.'s of my HBR-14 (on HBR website) are
covers,  under which are center core adjustment and two adj. screw heads
(caps, I assume).  I'm not sure which surplus unit these came from,  but the
radio works comparable to the HBR-16 w.r. to bandwidth of the Miller i.f.
units.  Now that I have a sweep generator,  maybe I should make a
quantitative comparison.  There is a commericial hamband set,  the NC-270,
that is similar to the HBR-16 lineup, with 50 Khz final i.f.  Its all-band
brother,  the NC-190, is another starting point if you're looking for an old
receiver to acquire.  The tuning mechanisms aren't quite as nice as an
Eddystone.  Another similar radio is the Hallicrafters SX-96 or 100,  if you
like a little more weight in your set.  These, like the HBR,  follow the
path of achieving selectivity with tuned circuits at low 2nd i.f. frequency
with 1600 khz or so 1st i.f. Ted Crosby would have you believe his homebrew
coils are high Q and better than average;  I have no reason o doubt this, as
my own correspondence with the man makes me think he knew what he was
talking about.   Meanwhile, SOA military sets like the 390, put more
selectivity up front with synchronized gear-tuned  circuits,  and achieved
final selectivity at 455 khz with more i.f. transformers in line.  Of
course, many other design factors and differences can be found in comparing
such sets.  Dan   

-----Original Message-----
From: hbr-bounces at mailman.qth.net [mailto:hbr-bounces at mailman.qth.net] On
Behalf Of Chad H. Phillips
Sent: Sunday, January 08, 2006 8:20 AM
To: hbr at mailman.qth.net
Subject: [HBR] Re: BC-453 IF Transformers

Hello, all! This is my first post to the HBR reflector. My situation is
similar to Tim KA0BTD's - planning an HBR-influenced receiver project,
almost ready to build but still wondering about 2nd IF transformers...

I started out researching ways to improve the low-end tube receivers I see
on eBay. I initially chose this route because I crave tube experience
(thinking, building, listening with tubes) but I am not interested in
competing with the well-funded collectors buying up all the good stuff.
While reading QST late one night, I came across Crosby's 1963 articles...
soon found Kees Talen (K5BCQ)'s excellent HBR website... and now I am intent
on building a receiver.

I have seen the junker BC-453's on eBay. On one auction photo, I could even
make out "85KC" stamped on the side. Can anyone advise on the
characteristics of each unit in the set of three, and (if different) which
ones are suitable for use in an HBR? Are they typically recoverable in good
condition? Any problems with deterioration of materials in the can? Is the
top-hat knob for adjusting coupling, or just a cover?

Incidentally, does anyone have any experience or opinions on constructing IF
xformers as described on the following website?:
http://www.angelfire.com/electronic/funwithtubes/IF_Can-1.html

Regards,

Chad KE4KMH
************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and
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************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and
construction notes...... via http://www.qsl.net/k5bcq/ there is also a
mirror (faster response)at http://k5bcq.edebris.com/
 

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr