+++++++++++++++++++++ From: alta Reply-To: alta at alta-research.com Organization: Alta Research To: cyr999 at extremezone.com, Elecraft Subject: Re: [Elecraft] Using RIT - RIT Mod Date: Fri, 5 Apr 2002 09:26:27 -0800 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. ++++++++++++++++ Reply-To: From: "Sverre Holm - LA3ZA" To: , "Elecraft at Mailman. Qth. Net" Subject: RE: [Elecraft] Using RIT - RIT Mod Date: Sat, 6 Apr 2002 00:08:12 +0200 Nice and elegant mod! Is it meant for the K1 or the K2 (or both), and has anyone else tried it? 73, Sverre ++++++++++++++++++ From: alta Reply-To: alta at alta-research.com Organization: Alta Research To: , "Elecraft at Mailman. Qth. Net" Subject: Re: [Elecraft] Using RIT - RIT Mod Date: Fri, 5 Apr 2002 20:38:09 -0800 I did it on the K1. I do not own a K2. ... Reed, K7FLY, K1 ++++++++++++++++++