Hi Bill (et al.),
>> I have used serial number 2552 and must agree with Bill.
>> It has the right architecture to be an excellent receiver,
>> but the filters are not good enough. I have also found
>> the opposite sideband rejection to not be quite up to
>> many other radios.
>
>While I'd agree that the filters could be better, since their rejection
>slopes are slightly shallow, I'd disagree about the receiver in
>general. The K2 has so little IMD crap in the passband that it is a joy
>to listen to. Even a very crowded band sounds quiet.
That's very true! The K2 sounds very nice compared to the
IC-765 and IC-735 that I'm used to, as well as the TS-940S
I used to own. It can be much less tiring to listen to than
many other radios. The receiver, in general, has very good
performance. However, when you start getting lots of strong
signals 1-2 kHz away, it doesn't do as well as some other
receivers, including the IC-765 that I always come back to.
On the other hand, the K2 is nicer for working the QRP-L
Fox Hunts(sm) on 40 meters, as there is no issue with lots
of strong signals that close. 8^)
>Remember that the K2 filters are setup in software. It is possible to
>mis-adjust the BFO settings and end up with poor rejection. It could be
>the problem you have with the opposite sideband is a mis-adjusted
>filter.
I went back to Spectrogram to try again. It's not the BFO settings.
It's the filter. On the other hand, maybe things are better with
the newer and better-matched crystals shipped with the current K2.
I haven't had the chance to use a newer version, so I can't comment
on that. Both my Icoms appear to have better opposite sideband
rejection than K2 serial number 2552.
>> However, the biggest problem I have with the radio is the size.
>> The tuning knob is way too small, plus there are additional
>> controls close by on its left, getting in the way when
>> you're trying to tune.
>
>The tuning knob is small, and the controls on the left are a bit close.
>Some hams have changed to an FT-100 knob, which allows one to tune
>using the dimple, which keeps the fingers away from the controls on the
>left side.
I tried the FT-100 knob, which I didn't like, and eventually
settled on the FT-900 knob, which is slightly larger, but
doesn't have a dimple. Actually, I find the dimple is only
useful for making large frequency excursions anyway. It's
not useful for general tuning nor for close-in tuning. Maybe
if I tuned with my right hand, the nearby controls wouldn't be
an issue, but, alas. In any case, I feel that the radio really
needs to be bigger (with a bigger tuning knob) and have the
controls farther apart.
>> I also don't like the fact that the sideband used on CW
>> is different on some bands. It's annoying when you're
>> used to the pitch of signals going in one direction as
>> you tune each band and then finding different behavior on
>> the K2. There is a "reverse" switch, but I don't think
>> one should have to use it when changing bands.
>
>The reverse works, and the mode is remembered on each band, so this
>shouldn't be a big deal. In reality, though, I haven't really noticed
>the reversed tuning.
You're right, it is remembered. The point was that the
operator shouldn't have to hit the reverse switch at all.
This particular human factor should have been thought about
and included in the design. I'm surprised that none of
the beta testers noticed this. In any case, it should be
very easy to correct in firmware. If done from the outset,
it would have been a zero-cost fix.
>> Overall, the receiver is very good in the presence of
>> strong signals (until you get very close, as Bill noted).
>> I very much like the single-conversion approach. It
>> would be nice if they had the ability to use at least
>> one 8-pole filter and, preferably, the ability to
>> cascade two 8-pole filters (like the old TS-180S).
>
>Biggest problem is -- where would you put it? The K2 is really squeezed
>tight. The SSB board is already crammed full.
Exactly! Some of these things simply cannot be corrected
on the K2. Maybe a physically larger K3 will address these
issues. (I hope, I hope, I hope!)
72/73,
____ / _____ /
/ ) / / /
/____/ ____ /___ (____ ____ /___ /___
/ ) / ) / ) ) / / ) /
/_____/ /____/ /____/ _____/ (____ / / / . . .
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: k3ph@ptd.net |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+
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