[Hallicrafters] A "preliminary" HT-37 look-see

[Bill Gerhold]

Phil,

>From your description, you may have found a low mileage 37.  My 37 that
I continue to use on the air also has the original tubes in it.  Did not
change a single one and they are still going strong.  Found my rig at a
Pennsylvania hamfest with the cord cut off.

I sandblasted the cabinet to bare metal, primed it and painted it a
close match grey.  The front panel was pristine as were the knobs,
aluminum trim, meter and of course the main tuning dial and glass.  A
real gem.

I replaced the large and small filter caps under the chassis.  The
multi-section cap on the top side chassis is still original as it tested
good.  The line cord on all 37's always need to be replaced.  Spray all
the pots and band switch.  The transformer is still original and has
been in use for about 1 year now with all tubes, no replacements or
modifications to keep down the heat.  If the transformer fails, I will
just get it rewound.  Important note, the bias to the final tubes must
be at -49 VDC, with key down.  If much lower than this, the plates of
the finals will very quickly turn cherry red.  Other minor details will
need attention also but first you have to turn it on.

As for the AT7's, the carrier balance controls on the front of the rig
will take care of any out of balance tubes.  Good luck with the rig.
With a nice vintage Hi-Z mic on the front end, it will sound great.  It
keeps the room warm and lights up the ceiling and surrounding walls with
a nice soft orange glow.

   73 from K2WH   
Hallicrafters, The Radio Mans Radio
            http://www.w9wze.org/
   http://groups.yahoo.com/group/The19Group/
 

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Philip
Atchley
Sent: Saturday, November 20, 2004 5:39 AM
To: hallicrafters at mailman.qth.net
Subject: [Hallicrafters] A "preliminary" HT-37 look-see

Hi Y'all,

Today I just HAD to do a "brief" survey of the overall condition of my
HT-37 
transmitter.  The power cord was hard, dry and cracked along it's entire

length, I replaced that with a nice new 3 wire cord.  Even if I decide
to 
eventually sell/swap it "as-is" I would NOT accept the liability of that

power cord ;-)

Here is what I found on this transmitter.
1.  ALL tubes except the 12BY7 driver and 6146 finals are original 
Hallicrafters branded tubes.  The RCA 6146's 'may' be original as they
are 
date coded '61 which matches the other tubes in the set (1961-1962).

2.  Tubes all tested good, BUT suspect a pair of 12AT7's in the Sideband

generator should be replaced, marginal, not balanced.

3.  I'm quite certain that I lucked out and got one with a good power 
transformer, at least it tests that way with the Ohmmeter etc.  BUT, I
won't 
apply power till it's well backed out, silicon rectifiers installed and
the 
5 Volt filament lines disconnected from the tube sockets to avoid the
common 
HV-5 Volt to ground shorts.

4.  It appears that if I do the above mods, replace all the filter 
capacitors, this puppy may be "good".

Next time I have a little "jingle" in my jeans I will probably order the

filter capacitors and rectifiers (and a couple 12AT7's) and see if this 
puppy will come to life.

How well do they work on CW?  Are they a CW op's delight or nightmare?

73 de Phil,  KO6BB
http://users.mercednet.com/beaconeer/
Merced, Central California, 37.3N  120.48W  CM97sh

***************************************************
* RECEIVERS:                                      *
*  #1. Homebrewed "Mitch Lee" Design              *
*  #2. Hallicrafters SX-71 (1955)& VLF Converter  *
* ANTENNAS:                                       *
*  #1. 20 Meter long "loaded" Sloper oriented E/W *
*  #2. Half Sized G5RV Inverted Vee oriented N/S  *
*  #3. Roof mounted Hustler 6BTV 6 band Vertical  *
*  #4. 15 Meter-band Inverted Vee oriented NE/SW  *
*                                                 *
* Number of different NDB's heard: 974            *
***************************************************

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