[AMRadio] Has anyone seen one of these?

BILL GUYGER bguyger at sbcglobal.net
Tue Jul 29 14:47:03 EDT 2008

Boy that's an interesting thought Don. My only objection to the theory, and I can't prove anything one way or the other, is that the top was only held on by 4 sheet metal screws, and given my monkey curiosity I might have opened it to see what was inside if I was the one that bought it. Also, the entire mass of the metal bits was somewhere on the order of about 2 or 3  3/4" by 1 1/4" bolts, which is about what the pieces were. One was threaded 3/4" dia. and about 1.25 long, another was about the same diameter and length and had a point machined on one end, and there were 2 other 3/4" pieces that might have been spacers of some kind.
Your idea definitely has merit. Who ever built the rig had significant sheet metal experience since the chassis's, front panels, and cheek plates were homemade and done pretty well. The builder was not however very electronically sophisticated so he might well have bought a pig in a poke from a conman.

----- Original Message ----
From: D. Chester <k4kyv at charter.net>
To: amradio at mailman.qth.net
Sent: Monday, July 28, 2008 11:10:07 PM
Subject: [AMRadio] Has anyone seen one of these?

> From: BILL GUYGER <bguyger at sbcglobal.net>

> ... What someone did was to try to make their own high(er) power 
> modulation transformer. There was a roughly cubical metal box with a fiber 
> board top. The top had 5 terminals mounted to it for the primary and 
> secondary connections. The top mounted to the box with 4 sheet metal 
> screws, and by the time I got it after it had sat in a garage in Waco for 
> 40+ years the fiber board was soaked with oil.
> I opened the top and found a 50-60 watt Stancor Mod. transformer sitting 
> on a piece of 1/2 " plywood with cardboard pieces packing the rest of the 
> box. There were also bits of steel stock that looked like machine shop 
> scrap because they had been turned. The whole thing had been filled with 
> transformer oil (which had turned to gelatinous goo) and a couple of holes 
> had been drilled in the covers of the Stancor transformer to allow oil to 
> fill its innards.
> I'm guessing that this might have been something that was sold in one of 
> those little ads in the back of QST or some such. I'm also guessing that 
> the metal pieces packed into the box along with the transformer were 
> supposed to enhance the magnetic properties of the transformer somehow.

I suspect whoever put that modulation transformer together added the metal 
pieces to enhance the weight, not the magnetic properties, and sold it, 
claiming it was a higher power transformer.  The guy who built the rig 
probably never suspected that he didn't have a bigger transformer.

But it's a good possibility that even with the oil, that the unbalanced DC 
saturated the core of the transformer.

I once used a swinging type filter choke that was rated at 5/25 henries, 500 
milliamps, but only 600 volts.  I took it out of its case and submerged it 
in a can of pole pig oil and used it in a 2500 volt power supply until I was 
able to find a choke rated for the voltage.  The submerged choke never 
crapped out and I used it for over a year.

Don k4kyv 

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