Mark,
Thanks very much for your reply!
Yes, you are finding the frequencies where the PLL goes out of lock. And yes
the frequency range will vary on each band. The bandpass filters will
probably limit the usefull range before the PLL goes out of lock. The KPA100
low pass filters may also affect the high frequency limits depending on where
the filter rolloff starts. Are you using a K2 or K2/100?
A list of ranges by Niel Skousen, WA7SSA, is on the Elecraft website at
http://www.elecraft.com/Apps/K2_GenCov.htm
however, it doesn't show the 160 or 60 meter bands.
While Niel lists the PLL high limit of the 80 meter band as 4167 kHz the
sensitivity drops off at about 4150 kHz due to the band pass filters. I also
believe that Niel's work was done on an early K2 and that the K2B or K2 with
the K60XV may have different ranges. I also expect that the component
tolerances will also affect the ranges somewhat.
So it looks like there is still a gap between 80 and 60 meters. Looks like the
low end of the 60 meter broadcast band will still be out of range. And while
the PLL might hold through the 49 meter band, I would expect sensitivity to
be poor.
Thanks for your research!!!
73,
Darrell VA7TO K2#5093
On January 21, 2006 08:02 pm, you wrote:
Individual results may vary, but here is what I found with my K2 (Rx
Only, of course):
Lowest frequency: 4.770 MHz
Highest frequency: 6.370 MHz
Notes: The VFO frequency continued to change on the LCD diplay above
and below the frequencies listed, however I think the PLL goes out of
lock beyond that range so the frequency didn't really change even though
the display did change. I think this is the case because I could here a
signal but it seemed to stay at the same frequency even though I was
spinning the VFO knob and saw the LCD display continue to change
frequency. I've noticed this on other bands as well. Also, the
sensitivity becomes less as you get out of the specified band, however
I didn't take the time to measure the change in sensitivity. I would
think the sensitivity change is due to the filtering for any given band.
Finally, I thought you might be interested in how high does the 75m band
coverage go so you know how much of a gap there is between 4.0 MHz and
the lowest frequency I listed above. Unfortunately I don't have a good
answer for you on that as the highest signal I heard was at about 4.007
(RTTY). Since everything else above that was just band static I
couldn't tell where it really dropped out, at least not without taking
the radio to work and using a sweep generator to figure it out. I know
that it either had really poor sensitivity at 5.000 MHz or it didn't
receive there at all when 80m was selected because I couldn't hear WWV
while I could when I had the 60m band selected. However, the low end of
80m seemed to be (again, with reduced sensitivity) about 2.770 MHz.
Assuming the same range as above for 60m (1.6 MHz), this would put the
high end theoretically at 4.370 MHz. Okay, and while I'm at it, 160m
covered down to 1440 kHz, however, again due to lack of signals I was
unable to determine the upper end. I did identify a signal at 2.084
MHz, but again I think it theoretically would be able to Rx up to 3.04 MHz.
I didn't really think about it much, but the assumption above for
frequency range (1.6 MHz) on bands other than 60m is not valid.
Somebody else may be able to comment better on that. I just proved that
to myself by scanning the 10m band quickly and found that the radio does
Rx over a 2 MHz range on 10m, so I guess the range does vary from band
to band.
--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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