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VFO tuning range of 150Khz

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AF6NI

VFO tuning range of 150Khz

I've had a couple of K1's but I am actually constructing my first one from a kit. I need to decide whether to set the VFO range to 80 or 150Khz. I am leaning toward the 150Khz because occasionally I like to go up to the slow speed CW portion of 40 (7.110-7.125 Mhz) and also because it would be nice to receive WWV at 10Mhz. Every K1 I've had to date has been set for the narrower tuning range.

I need to make the decision quickly since I'm about to choose which crystal to install for 30M. If you have a K1 that tunes 150Khz how do you like it? Do you find that the tuning is too sensitive and do you wish you had set it to the narrower tuning width?

Thanks.
Joe

"Hjalmar Duklæt"

Re: VFO tuning range of 150Khz

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Mike WA8BXN

Re: VFO tuning range of 150Khz

In reply to this post by AF6NI

Hi Joe,

Long ago when I got mine I chose to have my cake and eat it too. I built it
for 150 KHz but put a tiny dpdt switch on the back panel that allowed me to
put a resistor in series with the tuning pot at one end or the other
depending on switch position. The added resistor was the same resistance as
the pot as I recall. This halved the tuning range of the pot. Depending on
which end of the pot the added resistor was would resulting in tuning the
top or bottom half the the 150 KHz tuning range.

73 - Mike WA8BXN

-------Original Message-------

From: AF6NI
Date: 5/5/2012 4:51:19 PM
To: [hidden email]
Subject: [Elecraft] VFO tuning range of 150Khz

I've had a couple of K1's but I am actually constructing my first one from a

Kit. I need to decide whether to set the VFO range to 80 or 150Khz. I am
Leaning toward the 150Khz because occasionally I like to go up to the slow
Speed CW portion of 40 (7.110-7.125 Mhz) and also because it would be nice
To receive WWV at 10Mhz. Every K1 I've had to date has been set for the
Narrower tuning range.

I need to make the decision quickly since I'm about to choose which crystal
To install for 30M. If you have a K1 that tunes 150Khz how do you like it?
Do you find that the tuning is too sensitive and do you wish you had set it
To the narrower tuning width?

Thanks.
Joe

--
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Mike Morrow-3

Re: VFO tuning range of 150Khz

In reply to this post by AF6NI

> I've had a couple of K1's but I am actually constructing my first one from a
> kit. I need to decide whether to set the VFO range to 80 or 150Khz. I am
> leaning toward the 150Khz because occasionally I like to go up to the slow
> speed CW portion of 40 (7.110-7.125 Mhz) and also because it would be nice
> to receive WWV at 10Mhz. Every K1 I've had to date has been set for the
> narrower tuning range.

I have used the "150 kHz" option on my K1 for more than 11 years. I like it
very much, for the more complete coverage that you mention, and also for the
possibility of cross-mode (Morse vs. LSB) contacts on 40m. That is possible
because the "normal" K1 (which uses a filter board set for high-side mixer
LO injection) receives in LSB mode.

You will actually get a VFO span of 170 to 180 kHz instead of 150 kHz. The
10-turn potentiometer tuning is fairly linear since R19 was added to the
design ten years ago. That 17 kHz per turn is not all that fast or touchy.
What *is* touchy is the potentiometer itself, which has very little resistance
to rotary displacement as one's fingers leave the tuning knob. I uses a few
layers of thin soft felt hand-cut to form washers between the panel and the
back of the tuning knob to establish some barely perceptible resistance.

Those that have rolled their own 10m and 12m filter boards report that the
wide-span option is a plus for that as well.

I like the K1. Today and most days now, 15m is great (eat your heart out,
KX1 owners). The standard built-in speaker sounds great (sorry again, KX1).
The auto tuner has fairly good range (sorry again, KX1). The receive current
consumption (with back light) is little greater than 60 mA (sorry KX3 owners).

If you did not buy the LCD backlight option and you have not assembled the
front panel board yet...then stop and get one! It's extremely useful and
trivial to install as part of building the front panel board, but it's an
aggravating and troublesome item to back-fit afterwards. The K1 really
should be ***standard*** with every K1 sold.

I hate to emphasize the auto antenna tuners, though. They have become
standard items on all Elecraft rigs, and almost everyone here treats
them as *nothing but positive* in characteristic when used to match
some coat-hanger fed with dental floss. But ALL antenna tuners (especially
one made up of small toroids and 26 ga. wire!) insert losses. The better
one's antenna system can minimize the reactances inserted by a tuner the
better the station will perform. Sorry...that's just an inconvenient
truth for those lulled by the magic of a match-everything auto-tuner.
Some have difficulty even acknowledging that there is very good engineering
justification for using resonant antenna systems served by coax, even
under portable conditions.

73,
Mike / KK5F
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AF6NI

Re: VFO tuning range of 150Khz

In reply to this post by AF6NI

Thanks for the input. I'm going the 150khz route. I installed the 18Mhz crystal for 30 meters so I'm committed.
73
Joe

Ray Cadmus

Re: VFO tuning range of 150Khz

In reply to this post by AF6NI

I changed mine to the broader range so I could hit the slow spots on 40...

No problems - I would not go back.

73,

ray W0PFO

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On 05/05/2012 03:48 PM, AF6NI wrote: