I just finished building the K2 and am in process of checking it out. All
voltage tests, current tests, power tests, alignment tests and alignment
activities were completed successfully. I've been through the receiver
alignment twice just to make sure, and got good peaking on each band.
I'm hitting various receive problems that are just strange and I'm going to
have a little trouble explaining some of them, so please bear with me.
1. Receive sensitivity is not good. Using the same antenna, and with AGC on:
o Without the pre-amp on, the K-2 is nowhere near as sensitive as my K-1, nor
is it as good as my FT-897 (but the K-1 is better than the FT-897).
o With the pre-amp on, the K-2 is about as good as the FT-897, but still not
as good as the K-1.
The situation is better with AGC off, as good as or better than the FT-897, but
still not as good as the K-1.
It seems as if the AGC is having too much impact since I have to crank the AF
Gain almost all the way clockwise to get decent audio volume with the AGC on
(both headphones and speaker)?
2. On receive, stations are either there or not there.
In a correctly operating radio, as you tune across a station's signal, the
signal strength starts out lower and then picks up in strength and volume as
you reach the station's actual transmit frequency. Furthermore, if two
stations are near each other, you typically hear both of them.
In this case, if I hear a signal, I hear it at the same volume as I tune across
the signal's bandwidth. The perceived signal strength simply does not change.
The S-Meter does change value, but not the perceived signal strength in the
headphones or speaker.
Along with this, there is no interference from adjacent signals. I'm always
hearing the strongest station and only the strongest station at whatever spot
that my VFO is tuned to. Any other stations are simply not there, as if some
sort of really good DSP has completely eliminated all but the strongest station
at that point in the VFO (and I mean *completely* eliminated). As you tune
across, you can hear the specific point where one station stops being heard and
a different one starts being heard.
I do not have DSP -- this is a bare bones K-2 without noise blanker or anything
else. I have AGC turned off. The problem also appears with AGC on. In
addition, it appears in both VFO A and VFO B.
I have the squelch turned off.
I have checked, and I'm in filter 1 and I'm getting the correct readings from
aligning FIL1. When I go to FIL2, there's a similar effect -- except that the
bandwidth range across which I can hear the signal is much smaller (to be
expected with a tighter filter). At FIL3 I can hear only the strongest of
stations, and then across an extremely narrow signal bandwidth. Finally, at
FIL4 I cannot pick up even the strongest signals.
3. As I tune across a CW station's signal, there is no change in audio
frequency.
In a correctly operating radio, as you tune across a CW signal, there is a
change in the audio frequency of the signal, until you're at zero-beat, at
which time the audio frequency is whatever you've set your sidetone at.
In this case, once I hear a signal, I hear it at the same audio frequency
across the entire bandwidth of the signal for as long as I'm hearing that
signal (see problem 2 above).
The audio frequency at which I'm hearing the signal is not particularly my
sidetone frequency. It seems to be different for each different station, but
is the same for the same station. For example, I'm hearing a station at
14.100. As I tune across his signal, the audio on his signal is at about 800
Hz. As I tune past that (up), I hear another station and I'm hearing the audio
at something much lower, like about 500 or 600 Hz. If I keep tuning across the
dial, I'll hear other stations, each of which may or may not have a different
audio frequency than 800Hz. However, if I go back to the station at 14.100,
I'll again hear him at about 800 Hz and not some other frequency. I can hear
this particular station from about 14.099 to about 14.101, and his audio
frequency does not change as I tune the 2KHz range between .099 and .101
I get the same result with SSB signals. There is no change in the audio, and
thus most SSB signals are unintelligible because there is no way to tune in on
the station's actual transmission frequency. Every so often, an SSB station is
intelligible, and then no amount of tuning across its bandwidth makes it
unintelligible.
Note that I do not have the SSB module installed, and I'm not sure if I'm
supposed to be able to hear SSB in a bare-bones K-2 without the SSB module
installed (although it is my understanding that I should be copy SSB).
*****
I've been through the manual twice and can't find any features that I may have
inadvertently turned on to get these results.
Any suggestions would be appreciated. Thanks in advance.
Jon
KB1QBZ
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
