[ARC5] ATD Project: Dynamotor First

[Dennis DuValll]

This radio was written up in ER back in the early 90’s.  I acquired the unit from the Author a year or two later and ran it for a while back East and then later out here in CA where I now live.
Was working (sort of) when acquired.  I started out with a HB AC supply instead of the dynamotor.  Biggest problem encountered in the unit involved replacing the strings of (early) 2W carbon 
resistors the designers chose to use instead of single WW units with appropriate dissipation ratings.  Carbons all WAY out of tolerance of course.  

Ran the radio for several years as mentioned before. Reliable 40W carrier output on 160, 75 and 40M.  Frequency stability was very good on all bands.  Audio reports not so good,though.  Biasing 
scheme on the modulator tubes (cathodes at +28 vdc) had them running at about AB-1.5 and the 6L6 driver circuit kind of weird too but I never really dug into it.  I operated mostly with an AC supply 
but the dynamotors (I have a pair) gave the same results.

Maybe time to pull the unit off the shelf and give it another run.  Certainly a unique piece of equipment and radio history.


Dennis  DuVall, W7QHO






> On Aug 1, 2017, at 10:27 AM, David Stinson <arc5 at ix.netcom.com> wrote:
> 
> Making a start on the ATD project.  Built the cables and lubricated the dynamotor.
> 28 Volts at rated 50 Amps from two stacked Astrons with the parallel enable circuit
> will not  start it.  Time to go dig-out some surge caps.
>  
> 73 DE Dave AB5S
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