Elecraft › [K1]

K1 VFO Range Question

Classic

List

Threaded

6 messages Options

Curt

K1 VFO Range Question

I built my K1 awhile ago with a VFO range of 80 kHz, also a 4 band filter and 2 band filter.
With recent increase in QRM levels on 7030-7040+-, am considering expanding the range to 150 kHz.
This will allow me to work the old Novice segment on 40M. Seems the only change needed is the band crystal for 30M on the filter board and one capacitor on the RF board. Noting the caution in the
manual about using wider range with the 4 band filter am wondering what other folk's experience
has been with the wider range. I'd hate to foul up what has been a wonderful QRP rig.

Thanks and 73, Curt KB5JO
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Bob - W0GI

Re: K1 VFO Range Question

You really don't need to change the crystal, unless you want to receive WWV @ 10 mHZ. It would be easier to leave the crystal as it is, in case you go back.

As for the filters, if you leave them alone nothing will change on the band segments you currently use. On 40 meters, you may want to peak the filter a little higher at maybe 7.070 mHz. Since you probably won't use the extended range on the other bands, you can leave them be.

It is a bit touchy to tune, but then I like the ability to get to the old 40 novice band.

If you just do the VFO, it is easy to go back. If you like the change and want WWV, you can do the crystal later.

Brett Howard

Re: K1 VFO Range Question

In reply to this post by Curt

I really like the ability to get up higher and also like the "fast
qsy" ability that the wider range gives you. Some feel that its a bit
fiddly and you have to turn the knob a bit too finely but I honestly
kinda like the speed of the knob and I also like being able to pick up
WWV to verify my frequency counter and determine if I need to cal it
again.

~Brett

On Tue, Feb 16, 2010 at 7:17 AM, <[hidden email]> wrote:

> I built my K1 awhile ago with a VFO range of 80 kHz, also a 4 band filter and 2 band filter.
> With recent increase in QRM levels on 7030-7040+-, am considering expanding the range to 150 kHz.
> This will allow me to work the old Novice segment on 40M. Seems the only change needed is the band crystal for 30M on the filter board and one capacitor on the RF board. Noting the caution in the
> manual about using wider range with the 4 band filter am wondering what other folk's experience
> has been with the wider range. I'd hate to foul up what has been a wonderful QRP rig.
>
> Thanks and 73, Curt KB5JO
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Rick Dettinger-3

Re: K1 VFO Range Question

In reply to this post by Curt

Hi Curt,

I like the 150 kHz tuning range. Mine is actually 170 kHz, which, of
course, gives an average rate of 17 kHz per revolution with the 10
turn pot. I think this is still slower than the top rigs of my youth,
which we though was quite good. I don't remember hearing complaints
about the Drake and Collins tuning rates, which, IIRC, was in the 20
kHz per turn range. Of course, they did have larger knobs. I put a
K2 knob on my K1, but I don't think that was necessary. I had to ream
the hole to 1/4 inch. It should be possible to come up with a
capacitor size that would give a 125 kHz. range, which I think would
be ideal for 40 meters, but I haven't tried that yet.

73,

Rick Dettinger K7MW

> I built my K1 awhile ago with a VFO range of 80 kHz, also a 4 band
> filter and 2 band filter.
> With recent increase in QRM levels on 7030-7040+-, am considering
> expanding the range to 150 kHz.
> This will allow me to work the old Novice segment on 40M. Seems
> the only change needed is the band crystal for 30M on the filter
> board and one capacitor on the RF board. Noting the caution in the
> manual about using wider range with the 4 band filter am wondering
> what other folk's experience
> has been with the wider range. I'd hate to foul up what has been a
> wonderful QRP rig.
>
> Thanks and 73, Curt KB5JO

Steve KS1G

Re: K1 VFO Range Question

Hi! I've had an early (S/N) K1 since mid-2001; bought it already built from the original owner, has 80kHz bandwidth. Am I correct I just need to change C2 and re-peak the filter board to widen the range? Is tacking another cap in parallel practical? I'm also considering just re-aligning the VFO coverage to hit, say 7.030 or so and up, as my cw speed can't keep up with the faster ops below 7.025 or 14.025 anyway. Either way, any gotchas to look out for before I start disassembling a working rig to "fix" something that may not need fixing? I assume I have to remove the antenna tuner and 2-band filter board before I can work on the VFO.

73 de Steve KS1G

Don Wilhelm-4

Re: K1 VFO Range Question

Steve,

All you need to do is tack an NPO capacitor in parallel with the 68 pF
C2 - try different values until you find the range that yo want.
After finding the range, then adjust the turns on L1 to place the lower
end of the range where you want it.
No other tuning should ge required, although you could re-peak the
bandpass filters on transmit (use a low power level like 1.5 watts). If
it is working well now, do not movethe adjustments far - just re-peak
them. If you have the 4 band board, be certain to do the bands in the
proper order - 30 meters before 40 and 15 (17) m before 20.
Be aware that if you have the 30 meter band on that K1 you will lose
coverage of most of the CW portion of 30 meters by moving the bottom of
the range upward - all bands will move.

73,
Don W3FPR

Steve KS1G wrote:

> Hi! I've had an early (S/N) K1 since mid-2001; bought it already built from
> the original owner, has 80kHz bandwidth. Am I correct I just need to change
> C2 and re-peak the filter board to widen the range? Is tacking another cap
> in parallel practical? I'm also considering just re-aligning the VFO
> coverage to hit, say 7.030 or so and up, as my cw speed can't keep up with
> the faster ops below 7.025 or 14.025 anyway. Either way, any gotchas to
> look out for before I start disassembling a working rig to "fix" something
> that may not need fixing? I assume I have to remove the antenna tuner and
> 2-band filter board before I can work on the VFO.
>
> 73 de Steve KS1G
>
>