[AMRadio] Has anyone seen one of these?


D. Chester k4kyv at charter.net
Tue Jul 29 00:10:07 EDT 2008


> 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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