[Elecraft] K1: RF gain and RIT controls

[Tom Hammond]

Hi Bruce:

>1. Has anyone come up with a good RF gain control, aka AGC threshold control?
>Please, no lectures about how the K1 doesn't need it, or how the RF
>attenuator works great.
>
>2. In searching the archives, I found hundreds of posts about the RIT range.
>Too many to sort through. Is the mod in the manual the best and simplist for
>reducing the RIT range, or was there a definitive posting of a better one?
>While I'm at it, is there a drop-in replacement for the RIT control that 
>has a
>center detent?

You'll certainly no lectures from me, pal.

However, here's some info which appears to have worked for one builder:

   Date: Sun, 15 May 2005 15:42:01 +1200
   From: Ron ZL1TW <ron_w at clear.net.nz>
   To: elecraft at mailman.qth.net
   Subject: [Elecraft] K1 revisited

   Hi,

   In a recent posting I mentioned I was not happy with the AGC
   action of the K1 after pulling it out of retirement for a QRP
   Sprint on this weekend.

   This is an account of what I consider, improves the set
   generally. I claim no originality for the ideas, and any K1
   purists or designers might like to switch to the next message
   right now! ( Definitely YMMV)

   The AGC "problem" of giving a burst of audio when a strong
   signal made itself present was cured 99% by altering C31 to 1uf
   ( from 2.2UF) and replacing C67 with a .22uf cap ( was also
   2.2uf) That sped up the AGC action and after using the set in
   the first 1/2 of the Sprint last evening, I was more than happy
   with the AGC.

   However....probably being spoilt by the K2, I found the tuning
   rate a tad delicate for my fat fingers, and the RIT action was
   gross.

   OK.....I know it has a large range so the set can be used in
   SPLIT mode....but I doubt I will use that mode on the K1, so I
   looked in the Elecraft Reflector listings and dug out a
   solution posted on 20 Jul 2001 under the heading "Re: K1 RIT
   mod", where the RIT is modified to a logrithmic action that
   gives a small range of tuning over about the first 25% of the
   controls throw, ( each side) but still retains most of the
   original total range.

   It was a tight fit getting the parts in and I had to use 1/8w
   resistors to obtain a decent fit, but it works fine. Now the
   VFO band spread. I was using the 68pf cap for C2, which gave me
   a 80khz tuning range. I altered C2 to 47pf and added an extra
   turn on L1 , and that gives me a tuning range of 51khz. A wee
   bit under the 55khz we are allowed here, but perfectly
   acceptable to me.

   The second half of the Sprint event is on tonight, and I am
   looking forward to joining in with my "re-Vamped" K1 . From
   using the set last night, there is certainly nothing wrong with
   the K1's receiver. I had forgotten what a fun set it is.

   Cheers.......Ron ZL1TW

73,

Tom Hammond   N0SS