[Hallicrafters] More SX99 questions
n8ie at woh.rr.com
n8ie at woh.rr.com
Thu Feb 5 09:16:00 EST 2009
Hello Mark,
So the gimmick wire should be soldered to pin 3 of V5?
Thanks for the info, that is going into my SX-99 folder. :-)
73
Dan, N8IE
---- Mark Drakage <markdd at nc.rr.com> wrote:
> Hi, there should be a wire coming from pin 1 on T2 to pin 4 of V4. The
> gimmick wire coming from pin 3 of V5 is typically wrapped around the T2
> pin 1/ pin V4 wire at least one turn. Of course the gimmick wire needs
> to be insulated where it wraps around the other wire. Each turn produces
> about 1-2 pf capacitance. One turn should work fine. Doing this would
> also keep it from moving around from vibration. My S-40B and S-108 have
> the exact same circuitry for injecting a local oscillator carrier to mix
> w/ the IF signal coming out of the 1st If amp stage via T2.
>
> For anyone that owns an S-38 (not applicable on the a,b,c,d or e
> version), or a National NC-188, their gimmick wire wraps around the wire
> that connects the 2nd IF amp output transformer to the plate of the
> detector tube. This works OK if all you want to do is listen to CW but
> produces poor results for listening to SSB. Just unwrap the gimmick wire
> and move it to the same equivalent wire that feeds IF from the 1st IF
> stage output transformer to the control grid pin of the 2nd IF stage. In
> other words just like it's done on the S-99, S40 and S-108. This makes a
> vast improvement in audio quality when listening to SSB on S-38's and
> NC-188's. Reason is none of these receivers have a true product detector
> stage, but the pentode tube used in the IF stage acts as a much better
> virtual product detector for mixing the IF and LO than a diode detector
> tube does.
>
> regards,
> Mark
> KJ4FJK
>
>
> N8IE wrote:
> > THANKS!
> > I un-wired mine and let it loose near the pin and it works fine.
> > I guess I need to secure it so it does not move when bumping the radio
> > around or moving it.
> >
> > You guys a great, thank you all!
> >
> > 73
> > Dan, N8IE
> >
> > -----Original Message-----
> > From: hallicrafters-bounces at mailman.qth.net
> > [mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of rbethman
> > Sent: Tuesday, February 03, 2009 4:11 PM
> > To: hallicrafters at mailman.qth.net
> > Cc: ANTHONY CASORSO; n8ie at woh.rr.com
> > Subject: Re: [Hallicrafters] More SX99 questions
> >
> > Dan,
> >
> > The end that you found loose? Do NOT solder it! It is indeed the
> > "gimmick"!
> >
> > The insulated wire is simple left extended outside the shielding. I just
> > pullked mine out of its cabinet.
> >
> > Bob - N0DGN
> >
> > n8ie at woh.rr.com wrote:
> >
> >> Thanks Bob,
> >> Can anyone confirm this easily?
> >>
> >> When the problem first happened, switching the AM\CW switch made no
> >>
> > difference and only a local broadcast station could be heard with the volume
> > cranked. I found the wire loose and soldered it back to V5. This fixed the
> > problem except now when the AVC is on, I get a loud squeal, but the
> > sensitivity works fine otherwise. Sounds like it just slipped far enough
> > away from the tube to loose coupling.
> >
> >> I appreciate all the help guys!
> >>
> >> 73
> >> Dan, N8IE
> >>
> >> ---- rbethman <rbethman at comcast.net> wrote:
> >>
> >>
> >>> Yep, that is "another" method of creating a gimmick.
> >>>
> >>> If I'd dig out my SX-99 and look, I could confirm it. It is sort of
> >>> buried right now.
> >>>
> >>> Another project with too little time.
> >>>
> >>> Bob - N0DGN
> >>>
> >>> ANTHONY CASORSO wrote:
> >>>
> >>>
> >>>> I the Halli sets I am familiar with, the gimmick is just a piece of
> >>>> standard hookup wire stripped on one end only. The stripped end is
> >>>> soldered per usual but the other end is just wrapped around a tube
> >>>> socket pin to provide a few pf of coupling. It should not be
> >>>> connected directly.
> >>>>
> >>>> Tony
> >>>>
> >>>>
> >>>>
> >>>>> Date: Tue, 3 Feb 2009 14:10:22 -0500
> >>>>> From: rbethman at comcast.net
> >>>>> To: hallicrafters at mailman.qth.net
> >>>>> CC: n8ie at woh.rr.com
> >>>>> Subject: Re: [Hallicrafters] More SX99 questions
> >>>>>
> >>>>> Dan,
> >>>>>
> >>>>> A "gimmick" is a low value capacitor that is made by twisting what
> >>>>> is usually enameled wire a "few" turns. They were normally a low
> >>>>> voltage component.
> >>>>>
> >>>>> Bob - N0DGN
> >>>>>
> >>>>> n8ie at woh.rr.com wrote:
> >>>>>
> >>>>>
> >>>>>> While working on getting the SX99 back up and running I have
> >>>>>>
> >>>>>>
> >>>> another question.
> >>>>
> >>>>
> >>>>>> One of the main faults was the wire running from pin 3 of V5 to
> >>>>>>
> >>>>>>
> >>>> pin4 of V4 came off. It did not look like it was originally on very
> >>>> well to begin with.
> >>>>
> >>>>
> >>>>>> This wire is shielded and in the schematic is listed in part as
> >>>>>>
> >>>>>>
> >>>> C38 Gimmick 2uF.
> >>>>
> >>>>
> >>>>>> Exactly what is a "gimmick" capacitor?
> >>>>>>
> >>>>>> Thanks es 73
> >>>>>> Dan, N8IE
> >>>>>>
> >>>>>>
> >>>>>>
> >>> --
> >>> Bob - NØDGN
> >>>
> >>> ______________________________________________________________
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> >>
> >>
> >
> > --
> > Bob - NØDGN
> >
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