[Elecraft] Using RIT - RIT Mod

Fri Apr 5 23:30:25 2002

I did it on the K1.  I do not own a K2.

... Reed, K7FLY, K1

On Friday 05 April 2002 14:08, you wrote:
> Nice and elegant mod!
>
> Is it meant for the K1 or the K2 (or both), and has anyone else
> tried it?
>
>
> 73, Sverre
>
>
>
>
> Sverre Holm, LA3ZA
> Asker, Norway (59.8N, 10.4E)
> ---------------------------------
> www.qsl.net/la3za
>
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of alta
> Sent: 5. april 2002 19:26
> To: [email protected]; Elecraft
> Subject: Re: [Elecraft] Using RIT - RIT Mod
>
> On Friday 05 April 2002 05:45, you wrote:
> > Hi folks  -
> > I find it a bit frustrating to get the RIT "centered" ...
>
> Tim ...
>
> I had the same problem.  The following mod solved it for me.  I
> have been using this mod for over a year now, and is is very
> friendly.
>
> ... Reed, K7FLY, K1
>
> -------------------------------------------------------------------
>----- -----
>
> RIT FINE/COUSE MOD
>
> ***** This is improved Version 2.3, which supersedes the others
> *****
>
> I want the best of both worlds with RIT functionality.
>
> I want the RIT control to work *fine* (gradual) when I punch the
> button after a station drifts toward the edge of the 200 Hz filter,
> so that the station doesn't totally disappear after the RIT
> button-push.  Or worse, I could mistakenly lock onto the wrong
> nearby station!
>
> And, I want the RIT control to have *coarse* (wide-range)
> capability for those DX pileups.
>
> No room for a switch, so what's a ham to do.  I decided to add
> circuitry to the RIT control so that it is gradual at 12:00, and
> becomes increasingly coarse as it is rotated left or right.  That
> way, I keep the fine capability where I need it, yet do not lose
> much of the wide range of the control.
>
> I mounted the following components on the front of the
> microprocessor board, between the volume and RIT pots.  I snipped
> the middle lead from the RIT control and inserted the circuitry (in
> effect) between:
>
> Between the wiper of the pot and the circuit board, I inserted in
> parallel:
> (1) 330K ohm resistor (more fine) or alternatively 220K (not as
> fine), (2) diode, forward, and (3) diode, reverse.
>
> Then from the point on the circuit board that the pot originally
> connected to: (4) 100K resistor to one side of R3 RIT control, and
> (5) another 100K to other side of R3.  (6) Bridge (parallel) each
> of the two 10Ks that go to the RIT pot with two 33K resistors, one
> 33K parallelled with each 10Ks. The 33Ks are most easily added to
> the inside surface of the microprocessor board.
>
> Because this will narrow the total RIT range slightly, you may also
> want to add 10pf or 20pf to C7.  I opted to leave C7 at 39pf, and
> was left with a +- 3+ KHz range.
>
> If you want the effect to be subtle, with the fine zone between
> 11:00 and 1:00, use germanium diodes, like 1N34 or 1N60. If you
> want to increase the fine zone to between 10:00 and 2:00, use
> Shottkey 1N5711's or silicon power diodes like 1N4004.  For even a
> tad more fine-zone, use small signal silicon diodes.  If you want a
> spot at say 11:30 and 12:30 to have no change at all, remove the
> afore mentioned 330K resistor.  Without the 330K, you can set the
> control roughly in the middle (between 11:30 and 12:30), and it
> will always be right on the frequency of the non-RIT mode. :)
>
> At first, I opted for the germanium diode solution.  After
> operating for awhile, I decided that the effect was too subtle. 
> So, I finally settled on the 1N5711 Shottkey diodes in parallel
> with the 220K (also with the 100Ks as previously described).
>
> With these components, the fine zone is between 10:00 and 2:00. 
> The fine zone gently covers a bit beyond what you can hear with the
> 200 Hz filter engaged, which has increased the pleasure of
> operating the rig for me.
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-- 
Reed White  -  ALTA RESEARCH  -  www.alta-research.com
Phone: 877-360-2582  -  Email: [email protected]