K1: RF gain and RIT controls

[BruceAA5B]

I'm finally going to open the box I've had for 2 years and build a K1 so I'll
have a rig for the Australian outback next month! Before I start, a couple of
questions:

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?

Thanks!
    -Bruce AA5B
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[EricJ-2]

I soldered a 10K resistor across the RIT pot and magically cut the range in
half. It was easier than dealing with C7 on the rf board. I find RIT=Off a
satisfactory "center detent".

Per your request, I'll spare you my comments on the gain control as the K1
doesn't need one.

Eric
KE6US

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Wednesday, June 29, 2005 7:51 PM
To: [hidden email]
Subject: [Elecraft] K1: RF gain and RIT controls

I'm finally going to open the box I've had for 2 years and build a K1 so
I'll have a rig for the Australian outback next month! Before I start, a
couple of
questions:

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?

Thanks!
    -Bruce AA5B
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[Tom Hammond-3]

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 <[hidden email]>
   To: [hidden email]
   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

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[Sandy W5TVW]

Subject: [Elecraft] K1: RF gain and RIT controls


| I'm finally going to open the box I've had for 2 years and build a K1 so I'll
| have a rig for the Australian outback next month! Before I start, a couple of
| questions:
|
| 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.
|
    I've NEVER yet had a need for an RF gain control in the hottest most crowded
contest!  I VERY rarely use the attenuator in fact.


| 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?


    PLEASE LET EVERYONE KNOW with a post if you find a pot with a center
detent that will drop in the K1's front panel board!  I find the RIT VERY touchy
in it's present form.  I would really like to limit it to 1.5-2 khz MAX each side of center,
plus have a reliable "notch" to come back to for a center reference.  T'would be
very nice.
    Still in spite of this, best QRP rig I've ever had!

73,
Sandy W5TVW
| Thanks!
|     -Bruce AA5B
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[Scott-204]

I like the 150 kHz range on 30m for having WWV and on 20m (and 15m to some
extent) for big DX contests. While the tuning may be somewhat sensitive, it
is not difficult to control with a gentle touch. If you tend to stick close
to the QRP frequencies (or the "core" areas of each band) and don't need
WWV, 80 kHz is the way to go.

Scott N1AIA

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