[AMRadio] Modulator for DX60 available


Gary Schafer garyschafer at comcast.net
Fri Apr 14 12:04:00 EDT 2006


EF Johnson mad a similar screen modulator to the one WRL made. 

73
Gary  K4FMX

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Rev. Don Sanders
> Sent: Friday, April 14, 2006 11:56 AM
> To: Discussion of AM Radio
> Subject: Re: [AMRadio] Modulator for DX60 available
> 
> 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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> 
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