[AMRadio] New Transmitter


Rbethman rbethman at comcast.net
Tue Nov 28 14:52:56 EST 2006


Jack,

Regarding 813s modulating 813s, Tom, W3BYM, homebrewed just such a beast.

The 813 is an extremely rugged tube, fairly low in acquisition price, 
has a milled 1/8" graphite plate, and even as a "new" general class, I 
could NOT destroy one by mis- tuning my homebrewed amplifiers pair!

The ONLY way they EVER got destroyed was in shipping.  The amplifier was 
shipped overseas, the cabinet was an SX-28 one, (Please - no roasting!  
It was 1982!  I didn't know how much value it would have become - NOR - 
HOW to fix it at the time!), when the shippers managed to shorten the 
cabinet in "their" professionally packed crate, by at least 1 1/2 inches.

It is one FINE looking AND sounding plate modulated animal.  He 
published the construction and testing in Electric Radio.

My recommendation would be to get the back issues of ER.  The price of 
back issues is $3.75 ea.  The specific issues are:

       Number 153   -   February 2002
       Number 154   -   March 2002
       Number 155   -   April 2002

    The text goes into design considerations, parts selection, specific 
transformer information/identification, and tap selection.  Also issues 
as to modification of the B&W 850A bandswitch/coil assembly.

Bob - N0DGN


Jack Schmidling wrote:
>
> I am in the thinking stages of my next rig and would like some ideas.
>
> I am thinking of a pair of 813's or maybe even 4-250's but I can't 
> seem to find any specific plans or designs on line.
>
> There must be lots of them out there.
>
> I found a thing called the 813 Maul which is 813's modulated by 813's 
> but that is the only one.
>
> Any help?  Any other ideas?
>
> js
>
>

-- 
                       Bob Bethman - NØDGN
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