[Hallicrafters] HT-37 Questions

[rdhalste]

> At 09:58 PM 6/1/03 -0500, you wrote:
> >I am getting ready to fire up a HT-37 that has been dormant for
> >many years. I don't know much about this rig, but it looks good
> >and seems to be complete. I remember reading on this list that
> >the power xfomers are a problem spot. I plan to bring it up slowly
> >on a variac to hopefully reform the electrolytics,
>
>
> You will most likely blow out the transformer.
> DO NOT DO IT.
I guess I have to take exception to the VARIAC.  They are one of the best
mthods for getting low voltage and ramping it up.

It just takes common sense to use one.
You put an AC volt meter on the output, test the thing to make sure it works
right.
I've never seen one that had to be reqired for the "new, or modern"
voltages.
They are very forgiving as to what you hook them to, but again it takes
common sense.  The variac doesn't care if it's hooked to 105, or 125 volts
as long as it has ample core to handle the load.

In 40 years, I've never screwed up using one yet. Then again my training was
for doing that kind of thing for over 26 years.

I'd hate to see people give up using one of the best methods for bringing up
voltages from very low to eventually normal.

In industry, we even used to hook them to a small motor and limit switches
and had them ramp up over several days rather than remembering to step it
every few hours.  Our reason for ramping was different, but still
applicable.  We used them to control furnace temperatures for heating and
cooling where it took a couple of days to bring up the heat and a week or
more to bring it down.

This was in the days before programmable controllers.

We fused the primary for the rated cuttent (current drawn for normal
operation in this case) and the seconday was fused slightly lighter...It'd
blow if it went to normal operating current early on...That fuse was
replaced about 3/4 of the way through.  Again, this should be applicable to
ramping up the voltage to a boat anchor.

The nice thing is with the light fuses the thing is protected early on...

Depending on the motor drive you can take hours, days, or weeks to finally
achieve operating voltage and current.

Building one of these is also "relatively" easy.  Course the gears could be
expensive (worm gear  and worm gear wheel). From there it's easier to use
either a small variable speed motor through the worm gear step down, or a
clock motor of the correct speed to get the turn in the desired time.  It
may take several worm gear/worm gear wheel step downs to get the time
desired.

Personally I like the variable speed motor with enough spped range to go
from a day to a week.   Almost any variable speed motor can operate through
a larger speed range than 7:1

Just my thoughts,

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair? (S# CD-2)
www.rogerhalstead.com

>
> End of diatribe.
> (Further info to the poster.)
>
>
> Roy
>
>
> - Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
> 7130 Panorama Drive, Derwood MD 20855
> Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
> roy.morgan at nist.gov --
>
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