[AMRadio] Modulator for DX60 available

Rev. Don Sanders innatehealing at bigplanet.com
Fri Apr 14 11:55:50 EDT 2006

Geoff, while you may not have seen it, 
WRL made a screen modulator for a 
couple of their CW only small transmitters 
back in the 60's that was external to the 
transmitter and plugged into an accessory 
socket on the back of the transmitter. 
Rather rare now.   
BTW, I have copy of 2 articles for a 
Bias-shift modulator from the 50's and 
how to apply it to a DX60 for high 
level plate modulation. It uses a 
modulation choke for a form of 
Heising modulation and used the 
built in controlle modulator to drive 
the modulator tube- usually the same 
type as the final tube./ I recently 
found a 6 henry 200 mil choke and 
I am going to try it on my DX60B.
Healthfully yours,
                          DON W4BWS
----- Original Message ----- 
From: "W5OMR/Geoff" <w5omr at satx.rr.com>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Friday, April 14, 2006 9:27 AM
Subject: Re: [AMRadio] Modulator for DX60 available

> Alan Beck wrote:
> > I am sorry, did we work out how it could be interfaces with a DX 60?
> > Normally there is a transformer in parallel with the output plate I 
> > think and modulation is applied to the other side to "squish" the RF 
> > at Audio frequencies.
> > Is this what you mean by output iron?
> >
> >
> > John Lyles wrote:
> >
> >> I have a self contained, commercial looking modulator chassis that 
> >> would work well with a DX60 sized rig. It uses a pair of 807s and has 
> >> the input and output iron and driver tubes. It came from a SK's pile 
> >> this summer. If there is interest, I would part with it to help out a 
> >> DX60 conversion to high level plate modulation. Its a small thang. 
> >> Technical details available upon request.
> >
> Alan, I'm pretty sure John's statement was meant to say that the 
> external modulator he had, would work with a rig that was around the 
> same size (ie: power output of around 50w) as a DX-60.
> Of course, we all know that typical high-level plate modulated AM 
> requires a modulation transformer that is connected in series with the 
> B+ supply from the power-supply of the final, to the final stage 
> itself.  The audio generated by a typical push-pull Class B modulator is 
> coupled via the modulation transformer to the B+ line.
> I might be mistaken, but I don't think I've ever seen an 'external' 
> modulator deck that was built with the intention of  screen/grid 
> modulating an RF final.
> Hope that helps clear up some confusion.
> --
> 73 = Best Regards,
> -Geoff/W5OMR
> A: Yes.
> > Q: Are you sure?
> >> A: Because it reverses the logical flow of conversation.
> >>> Q: Why is top-posting annoying in email?
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