[Hallicrafters] HT-37

[Mark Bell]

Hi Bob --

Don't typically check email in the AM,  but gee, we got more snow today!!
So here I sit, waiting for the plow so I can get out......

Comments embedded.

----- Original Message -----
From: "Robert Stachurski" <WB4RFF at worldnet.att.net>
To: <hallicrafters at mailman.qth.net>
Sent: Friday, February 28, 2003 1:17 AM
Subject: [Hallicrafters] HT-37


> I did change out all of the electrolytic capacitors and resistors in the
bias supply but that bias was still reading a bit high and the manual said
that the bias voltage is VERY critical.

OK.  I'm going to have do dig out the schematics this weekend.  One
possibility -- what's your AC Main voltage?  This will account for higher
secondary voltages.  The other secondary voltages you measured, where they
"dead on",  or all a bit higher?

> When I replaced the resistors and electrolytics in the pwr supply I used
components that exceeded the specs in the parts list (wattage and % tol. for
the resistors ; voltage for the caps).  The components that are made today
are much smaller than those that were made when this xmitter was first
manufactured.

Yep.  Sometimes you'll need to replace a carbon comp 1/2 Watt resistor with
a 1W metal film resistor as the new 1/2 W metal film resistor's leads aren't
long enough!  Generally that's OK to do, but keep in the back of your mind
that perhaps the original 1/2W rating was intentional.  Also, for power
supply apps, as long as the capacitance is close to the original (try not to
go lower), and the voltage is at least the same as the original cap, you'll
be fine.

> Ideally I would have liked to restore this HT-37 to museum grade but a
quick eyeball survey told me that this was an impossible task.

There's been many discussions on this topic, all interesting.  As a general
observation, I've found that most hams do what is called "Electrical
Restoration" or "Functional Restoration".  I have no problems with using
modern components under the chassis.  Full restoration (defined by using
only era components) is more aptly practiced by the folks that restore BC AM
radios.   You might frequent their newsgroup;  I've leared a lot from
following their discussions!   Also, and this is a pet rule of mine,  I
don't mind using modern components, but whatever I do I try to make
reversable so that in the future, I (or another owner) could restore the
radio using era components.

Instead of tossing out those old paper caps, stick them in a drawer;  one
day you might want to try stuffing them with modern caps.  That way you'll
have the "real" look.

>I will let you know from time to time how the work is progressing

Please do Bob!  You'll find this group's denizens ready to lend a helping
hand (and some really bad jokes from time to time! )

73 Mark K3ZX