? How many peak volts on your 'scope? With "normal" ALC indication, my
TS-440S overshoots to about 120v-p. into 50-ohms. .
I didn't measure it on my scope because I thought I needed a fast
peak-reading or storage scope. I have a peak-reading RF DVM now, but I think
the minimum pulse width is 1ms. One of these days I'll see if my HP scope is
fast enough to show it in the phosphor persistence.
The test procedure you describe in a other post implies that you've tested
the 440 only for SSB overshoot. Try it with CW. While a sharp syllable might
have a pretty fast rise time, I would bet that the CW waveform rises much
faster, exacerbating the problem of slow rise time on the ALC. Also, QSK CW
is likely to cause a stream of spikes, whereas SSB will probably cause
spikes mostly when the VOX is initially tripped. I found this to be true
under contest battle conditions -- the 87A tripped much more often in CW
contests than SSB contests. I'm sure when it did trip in SSB contests I was
frantically bleating my call.
? What if the ALC meter only occasionally flickers?
Same deal.
? Interesting. Kenwood has also designed some painfully problematic
AGC circuits.
Well, another reason I replaced the 950 with a 1000mp is that the 950
overloaded with strong adjacent signals during contests. I'm not sure that's
exclusively an AGC problem, but I'm sure it's involved. I've always thought
the IF filters on the 940 and 950 are not very good and compound the
problem. I compared the 950 side-by-side with a lowly FT-990, and the 990
allowed me to copy much weaker signals in crowded band conditions, even
though optional crystal filters are only installed in one IF (that's all you
can do.) I think the FT-1000MP with INRAD preamp is even better. I was a
Kenwood man for 12 years until I spent some time listening to the FT-990 and
FT-1000mp (audio hiss and all.) The 950 is the best-sounding SSB rig I've
ever used, both transmit and receive (although it overloads there, too.) But
the Yaesu rigs really shine on CW.
73, Dick, WC1M
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