[Boatanchors] Variac low?

[StephenTetorka at cs.com]

Guys - thanks a bunch for all the help.
Permit me a moment to share this with you.

The variac is from an 'interesting' home brew 2x813 rig.
The gent was a 1 x 3 in 4-land and spent his last years as a 'hermit'.
It's said he once had a Motorola dealership, so he knew radio.
His rig is a work of 'art' and densly packaged into two 9 inch rack mounts.
It's also said he operated with the open power supply at his feet.

His variac had its knob 'eye-to-the-sky' so it can easily be turned from the top with the PS on his floor.

Its neatly encased in a food blender base - a most creative and suitable packaging solution I'd say.
It, along with the all top-side components on the PS were tightly nylon tie-wraped.

Every component and the chassis top-side and under was painted red.
Everthing.

The RF deck hasn't 2 square inches of open space.
Here too, everything is densly packed.
He used vacuum variables both C1 and C2 - the latter being motor driven for 'automatic' tuning as his little hand written label read.
The RF deck is not painted - its au'natural.

I have used his variac since it was relatively easy to free from the assembled mass.
Its planned for use on my upcoming 4 x 813 AM/CW rig which is why I got the Red Rig for parts.

I took out the 100 watt light bulb that was in series with the AC line on the variac input.
Got full ( 116.7 VAC) to the 5U4 power supply.

The bulb prevents damage from possible shorts when one fires up something for the first time.

This power supply is from a 6-foot rack AM/CW rig made by W2PLY in 1948.
It has 5 rack sections.
Back then 'easy bandswitching' was IN since the receivers had incorporated easy bandswitching.
So Hams found ways to quickly change bands on their transmitters, too.

One method is to use a series of 6L6 in doubler fashion.
Pre-tune the grids for 80, 40, 20 & 10 ( no 15) and all you have to do is switch band and ajust the final tune.

I'm in the process of restoring George's home brew.
Also restoring some dormant brain cells from when I last had my license 40 years ago.

At this time, I wish to Salute all the 1 x 3 hams who made the best with the technology they had at the time.
And they did it with their own hands!

If we Hams can 'see farther' today - its because we are standing on their shoulders.

Warm regards & Seasons Wishes,
Steve
WA2TAK







Fred Olsen <fwolsen at wi.rr.com> wrote:

>StephenTetorka at cs.com wrote:
>> Testing a low voltage power supply.
>> However, the AC in was only 90 VAC out from the Variac at max control.
>> Variac by itself 115 VAC at max control.
>
>First, it's just possible that you might be overloading the variable 
>autotransformer.  The idling current (you didn't say that the PS was 
>loaded) of a very large supply might exceed the current rating of a very 
>small 'Variac'.  Can you measure the current out of terminal 3 (usually)?
>
>Given that you have the 'Variac' wired correctly it would seem that you 
>have it wired for straight line rather than boost.  Fine.  But then the 
>question arises of why you only get 115 at no load.  It's very uncommon 
>to have that low a line (mains) voltage in the U.S. or Canada.  So where 
>are you and what is your measured line voltage?  What make/model is the 
>autotransformer and how is it wired?
>
>If all else is correct might the 'Variac' be defective?  Perhaps a 
>cracked core?
>
>Good luck, be safe,
>Fred
>-- 
><><
>--
>Outgoing checked by eTrust EZ AV
>
>