[JMS] 250 Watt modulator for 90881

[C E]

Hi Bill:
I have to take a look at that article. The Radio
Engineer's HB is one of my favorite, sometimes topping
the ARRL HB. Cal.

--- Bill  W2DGB <w2dgb at ptd.net> wrote:

> Cal,
> 
> Just for your background information, the 12th Edn
> of the Radio Handbook
> (Editors and Engineers, 1949) details a 100-watt 811
> modulator using parts
> from the ART-13. I would think you could easily get
> it up to 125 watts, and
> would only have to be concerned about any mismatch,
> and how significant it
> would be.
> 
> Bill Fizette   w2dgb
> 
> ----- Original Message ----- 
> From: "Dennis Petrich" <dpetrich at wavecrest.com>
> To: "'The James Millen Society Members Email
> Reflector'"
> <james_millen_society at mailman.qth.net>
> Sent: Wednesday, July 26, 2006 9:46 AM
> Subject: RE: [JMS] 250 Watt modulator for 90881
> 
> 
> > Hi Cal,
> >
> > I don't exactly what you have but it sounds like
> it has the right size to
> > work.  Most military transformers were under rated
> so I would suspect it
> > would handle the power OK.  Now if it can hit the
> impedances you need,
> > you'll be in like Flint....
> >
> > Ciao, Dennis
> >
> > -----Original Message-----
> > From: james_millen_society-bounces at mailman.qth.net
> >
>
[mailto:james_millen_society-bounces at mailman.qth.net]On
> Behalf Of C E
> > Sent: Tuesday, July 25, 2006 8:48 PM
> > To: james_millen_society at mailman.qth.net
> > Subject: [JMS] 250 Watt modulator for 90881
> >
> >
> > All:
> > After reading Dennis Petrich article on making a
> plate
> > modulator for the 90881 amp, I've got the "itch"
> to
> > make one myself. I initially thought of using an
> > ART-13 item but some have said that it might not
> have
> > enough power handling capabilities (which I'm
> almost
> > inclined to believe might not be all that true
> since
> > it is rumored that the xfrmr has been used at the
> 250
> > watt levels).
> >
> > I have, however, stepped across a unit that
> contains
> > an 811 modulator. It is marked "Modulator Panel
> > PN-10-B" and with a red lable "Modulator Unit Type
> > 5001A AM #29. It is a Signal Corps/Air Ministry
> unit
> > that came from the 1950's. The modulator
> transformer
> > is a hefty piece of iron about twice the size of
> an
> > ART-13 iron with large ceramic standoffs for the
> > modulator unbal out and B+ in.
> >
> > Does anyone have any idea what I have? If so, let
> me
> > know. Cal, N6KYR/8
> >
> > __________________________________________________
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