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Date: Tue, 15 Jan 2002 15:31:05 -0800
From: Wayne Burdick <n6kr at elecraft.com>
Organization: Elecraft
To: St-George <stgeorge at bluevalley.net>
Cc: elecraft at mailman.qth.net
Subject: [Elecraft] Re: K1 Wide-Filter Receive??

Chas,

You could add a small toggle switch on the right side panel that places
up to about 12 volts at pin 1 of RP1 (in the crystal filter circuit). It
wouldn't help to go much higher than this, even though the 1SV149 is
rated at up to 15 V absolute max. The leads don't even need to be
bypassed, as long as they're kept short. (C37 provides bypassing at this
point in the circuit.) If you use or plan to use a KTS1 tilt stand or
KBT1 internal battery, you'll have to be careful where you mount the
switch. 

The higher the voltage, the wider the bandwidth, but you'll also have
higher ripple amplitude in the passband (this may be of secondary
importance). Also, as you go wider, the BFO will no longer be positioned
optimally, so you may have poor opposite sideband rejection at low audio frequencies.

73,
Wayne
N6KR


St-George wrote:
> 
> Hi Gents,
>     Love my Little K1, but sometimes I really want to hear just whats
> "going-on" in a very wide 6-8KC bandwidth like my great old tube receivers
> can do.
>     Question: Is there any way a simple mod could be done with a switch that
> would allow a K1 to temporarily receive a wide spectrum of many KCs by
> by-passing the crystal filter?
>     I'd love it!
>     Thanks for reading,
>     Chas  w0ei

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