[Elecraft] K1 IF Amp Mod?

[r j]

Hi.

I have noticed that the K1 and Sierra rcvrs are very similar (as 602 based
designs). The main difference is imo that the Sierra has a MC1350 IF amp
(as has the K2 btw) followed by an LM386, but the K1 seems to do all
amplification after XFIL on AF frequencies using LM386+LM380.

Could/have the K1 be(en) modified with an IF amp and IF based AGC?

Thanks.
Roy
RF Tinkerer

[WILLIS COOKE via Elecraft]

Since you consider yourself as an RF tinkerer, it sounds like an interesting experiment. Since the technology in the K1 predates my interest in Elecraft, probably the up to date inclusions in the Sierra were not available when the K1 was designed 20 years or so ago. The K3 design is not getting long of tooth and the KX3 is the ultimate QRP design from Elecraft. It does not sound like a design change that will make Wayne and Erik any money!

Willis 'Cookie' Cooke, TDXS DX Chairman
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart


On Friday, October 17, 2014 1:16 PM, r j <rjinspace at gmail.com> wrote:



Hi.

I have noticed that the K1 and Sierra rcvrs are very similar (as 602 based
designs). The main difference is imo that the Sierra has a MC1350 IF amp
(as has the K2 btw) followed by an LM386, but the K1 seems to do all
amplification after XFIL on AF frequencies using LM386+LM380.

Could/have the K1 be(en) modified with an IF amp and IF based AGC?

Thanks.
Roy
RF Tinkerer
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[r j]

"... probably the up to date inclusions in the Sierra were not available
when the K1 was designed 20 years or so ago..."

The Sierra predates the K1. The NE602 mixer and MC1350 IF amp was in common
use long before the Sierra was designed and even longer before Elecraft was
formed. Elecraft used MC1350 in K2, but chose to substitute it with all AF
amplification in K1.

When - one day - the K3 and all IcoYaeWoods are irrepairable junk (due to
special technology/chips/firmware), you can always rip apart your dead and
dusty K1 or K2, throw away the microcontroller and the display, put in a
few jumpers on the RF boards, and voila - you have an all analog radio that
you can repair from your component junk box and (then) obsolete fleabay
ICs. In the exact same way as people do 50+ years old tubes today.


" No surprise." Yes, I know. That is why I wonder why the IF amp was
changed for an AF amp.

Roy
RF Tinkerer

Post by r j
Hi.
I have noticed that the K1 and Sierra rcvrs are very similar (as 602 based
designs). The main difference is imo that the Sierra has a MC1350 IF amp
(as has the K2 btw) followed by an LM386, but the K1 seems to do all
amplification after XFIL on AF frequencies using LM386+LM380.
Could/have the K1 be(en) modified with an IF amp and IF based AGC?
Thanks.
Roy
RF Tinkerer