Good News - At the rear of the bottom end of the plate bars, there are two
overlapping, aluminum, horizontal fingers welded on to the bars, that are
acting as a capacitor. I decreased the spacing between these two tabs by
about 50%, and now I can get the plate tuning to resonance at 146-147MHz.
Efficiency has increased to between 50 and 62%, depending upon how high I
push the amp (more power, more efficiency).
Hope this helps someone in the future.
73
Eric
kk2ed
----- Original Message -----
From: "Eric Lowell" <elowell@maine.rr.com>
To: "Eric Dobrowansky" <kk2ed@comcast.net>
Sent: Monday, September 22, 2003 10:01 AM
Subject: Re: [Amps] Motorola 375w VHF amp w/ 2x8560AS
> Hi Eric,
>
> I don't have the HP manual anymore. Sorry. Have you checked local 2-way
> shops?
>
> GL, Eric
>
> ----- Original Message -----
> From: "Eric Dobrowansky" <kk2ed@comcast.net>
> To: "Eric Lowell" <elowell@maine.rr.com>
> Sent: Sunday, September 21, 2003 10:30 PM
> Subject: Re: [Amps] Motorola 375w VHF amp w/ 2x8560AS
>
>
> > Thats my main problem - I don't have the manual. I have other manuals to
> > cover the receiver and exciter, but I need the correct manual to cover
the
> > PA.
> >
> > I'd greatly appreciate any help you can offer in regards to the manual
> > (mainly the schematic).
> >
> > Thanks
> > Eric
> > KK2ED
> >
> > ----- Original Message -----
> > From: "Eric Lowell" <elowell@maine.rr.com>
> > To: "Eric Dobrowansky" <kk2ed@comcast.net>
> > Sent: Sunday, September 21, 2003 10:19 PM
> > Subject: Re: [Amps] Motorola 375w VHF amp w/ 2x8560AS
> >
> >
> > > Hi Eric,
> > >
> > > Have you got the Motorola manual? I think the part values are in there
> > that
> > > you'll need to make the change. I'll poke around in the office
tomorrow
> > and
> > > see if I've got one still.
> > >
> > > Good luck, Eric W1EL
> > > ----- Original Message -----
> > > From: "Eric Dobrowansky" <kk2ed@comcast.net>
> > > To: <amps@contesting.com>
> > > Sent: Thursday, September 18, 2003 1:20 AM
> > > Subject: [Amps] Motorola 375w VHF amp w/ 2x8560AS
> > >
> > >
> > > > Hello ALL,
> > > >
> > > > I am attempting to bring a 153MHZ Micor 375w 2x8560 PA down to the
> > 147MHZ
> > > > ham band.
> > > >
> > > >
> > > > Currently, the grid and loading controls tune/peak with no trouble,
> but
> > > the
> > > > Plate cap is at it's maximum before I quite reach resonance. The amp
> > > > efficiency isn't all that good either - 260ma Plate @ 1400v keydown
> > yields
> > > > about 125w output, about 35%.
> > > >
> > > > Has anyone modified one of these "Motorola Micor" rf decks? Can I
> just
> > > add
> > > > some capacitance (ie: a doorknob cap or two) in parallel with the
> Plate
> > > > tuning cap? How much -5-10pf?
> > > >
> > > > Has anyone made notes or documented the re-tuning of one of these
amps
> > to
> > > > the 2m band?
> > > >
> > > > Any suggestions greatly appreciated.
> > > >
> > > > Thanks
> > > > Eric
> > > > KK2ED
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > Amps mailing list
> > > > Amps@contesting.com
> > > > http://lists.contesting.com/mailman/listinfo/amps
> > >
> > >
> >
> >
>
>
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