[Elecraft] increasing receive gain

Mon Sep 23 11:08:00 2002

Wayne & others making this mod:

What would you suggest as a absolute minimum value for R1 considering
overall RX performance?

That said, I changed mine and tested it "under fire" during the NJQRP
Sprint.

After trying a few different values I settled on 33k ohms. With this
value, and the K2 preamp switched on, my K2's S-meter reading matched
closely with my Icom 746pro (preamp off). With the K2 preamp off the
S-meters match within about 3 "S" units (I spot checked signals on 15,
20 and 30m). I thought about setting R1 lower, to get the Icom and K2 to
match S-meter readings, both with preamps off. But, I feared the stage
gain might be too high, and degrade overall RX performance.

What test(s) would anybody suggest to evaluate the suitability of a
particular R1 value? (tests that can be preformed without a full
compliment of lab equipment preferred)

What I noticed most during the Sprint was the elevated noise level on
40m, I was running the K2 with Preamp on. Usually I have the preamp on,
RF gain at max, and AF control between 9-11 o-clock (depending on the
other station's signal strength). With R1=33k, while on 40m with preamp
on, I found setting the RF gain control to 3 o-clock a better choice to
reduce background noise. Noise on other bands was not a noticeable and
running RF gain at max, preamp on, and AF gain at ~9 o-clock worked
well.

73, Rod N0RC

----- Original Message -----
From: "Wayne Burdick" <[email protected]>
To: "Elecraft" <[email protected]>
Sent: Sunday, September 22, 2002 11:18 AM
Subject: [Elecraft] increasing receive gain

> Once a K2 is assembled and aligned correctly, its overall receive gain
can be increased,
> if desired, by reducing the size of resistor R1 on the Control board.
This resistor is
>