[R-390] Modded my R-390A...

Thu, 24 Oct 2002 13:11:10 -0400

Yup.  Roy certainly is a class act and has given me a lot
of encouragement.  Don't think he would do something
like that maliciously.  IF he did not give credit, it was just
an oversight.

Scott

----- Original Message -----
From: "Scott, Barry (Clyde B)" <[email protected]>
To: <[email protected]>
Sent: Thursday, October 24, 2002 10:04 AM
Subject: RE: [R-390] Modded my R-390A...

> Helm,
>
> I hate to see Roy's name dragged around that way.  How do you know the
email he sent to Phil did not give you credit for the design?  I'm not
trying to start a flame war here, but I think you have insinuated something
that may not have occurred.  Roy may have simply forwarded something to Phil
that was originally from you (or mentioned you as the designer/author).
From Phil's post, it is unclear what was sent and I don't think accusing Roy
that way is a bit uncalled for.
>
> Regards,
>
> Barry - N4BUQ
>
> > -----Original Message-----
> > From: Helmut Usbeck [mailto:[email protected]]
> > Sent: Wednesday, October 23, 2002 6:29 PM
> > To: Philip Atchley; [email protected]
> > Subject: Re: [R-390] Modded my R-390A...
> >
> >
> > Phil,
> > Glad you liked my audio mod, Roy Morgan likes to send other
> > peoples work
> > out without giving credits. I havn't had any problems with
> > the zener on
> > the 6aq5 shorting, but you never know.  Mine's been cooking
> > for a couple
> > of years now.  In regards to the output impedance using the 5000z
> > transformenr it matches a 6aq5 triode fine with -15 bias.  The
> > distortion is a lot less than running as a pentode.  I would also run
> > -17 to -18 volts instead of -15 as a pentode.  Draws less current and
> > should sound better.(My original setup before I went triode.)Just
> > courious if you removed the 2 feedback paths in the original circuit.
> > There are other changes than just changing the output tube.  Just
> > courious if you did them.
> >
> > www.geocities.com/husbeck for the complete mod.
> >
> > Regards,
> > Helm.  WB2ADT
> >
> > Philip Atchley wrote:
> > >
> > > Hello all.
> > > Today I did a couple things that I've been wantietenplg to
> > do to the R-390A.tch
> > > years).   Yes, I put a 220 Ohm 25 Watt (I had the 25W)
> > resistor in the power
> > > supply to "compensate" for the diodes smaller Voltage drop.
> > >
> > > Secondly, I wanted to change the "Local" audio amplifier to
> > a circuit that
> > > would provide more drive to my speaker (which is not overly
> > efficient)..
> > > Sometime back Roy Morgan had sent me an email converting
> > the local audio to
> > > a 6AQ5 which was wired as a Triode.  This same "mod"
> > changed several othervolts
> > > items on the audio deck for better biasing of the 12AU7
> > tubes, removal of
> > > feedback etc.  ALL being aimed towards lower distortion and
> > wider bandwidth.
> > > This was GOOD as I had a small audio output transformer
> > scrounged from a set
> > > that used a 6AQ5 as the output section.  This transformer
> > had BOTH an 8 Ohm
> > > and a 500 Ohm tap on the secondary.  I chose to use the 8
> > Ohm and ignor the
> > > 500 Ohm winding (I have the "line audio" output if I need
> > 600 Ohms.  For
> > > this reason, rather than wire the 6AQ5 as a Triode I opted
> > to use it as a
> > > Pentode so it'd match the transformer well.  And rather
> > than use the 15 Volt
> > > Zener for Cathode bias of the 6AQ5 (as the mod sheet
> > showed) I chose to use
> > > a 390 Ohm 2 Watt wirewound resistor.  I DON't like Zeners
> > in cathode biased
> > > circuits as they 'usually' fail in the SHORTED mode and
> > this would zero bias
> > > the output tube, drawing excessive current and possibly
> > (likely) doing other
> > > damage!!!
> > >
> > > I removed the original "Local Audio" output transformer and the new
> > > transformer fit and mounted well in the original space,
> > though only with one
> > > mounting leg screwed down.  A terminal strip was mounted
> > below chassis to
> > > use as tie lugs for the leads that connected to the
> > original transformer and
> > > the new transformer.
> > >
> > > THIS MOD IS 100% REVERSABLE AS I CEKPT THE TRANSFORMER ETC
> > AND NO HOLES WERE
> > > DRILLED!
> > >
> > > The results??  Fidelity is much improved and the audio
> > drive is more than
> > > sufficient for the speaker I'm using.  YES I know this is a
> > communications
> > > receiver but that doesn't mean it has to have lousy audio 8^)
> > >
> > > 73 de Phil  KO6BB
> > >
> > > Loving home provided for wayward Boatanchor Receivers.
> > > LF Modified R-390A '67 EAC  W/Heath HD-11 Q-Multiplier.
> > > Hallicrafters  SX-71 ('53) & 5R10A ('53).
> > > Homebrew 'Hybrid'  Longwave CW receiver.
> > > Realistic  DX-160 & SP-150 ('78).
> > > Merced, Central California,
> > > 37.18N  120.29W  CM97sh.
> > >
> > > _______________________________________________
> > > R-390 mailing list
> > > [email protected]
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