From: flloyd@l1-a.West.Sun.COM (Fred Lloyd [Phoenix SE])
Newsgroups: rec.radio.amateur.misc
Subject: Adventures in the shack of AA7BQ (long)
Date: 6 Oct 1992 18:49:16 GMT
Organization: Sun Microsystems, Phoenix, AZ
NNTP-Posting-Host: l1-a.west.sun.com
Summary: IC-735, TS-940, IC-761, KAM, 1978 Volvo...


Recent Adventures in the Shack of AA7BQ

Well, up until recently the hamfest season has been kind of dry around
here for the last few months and so I've had the incredible urge to
trade some equipment.  The following is an account of my experiences
with three radios, the IC-735, the TS-940S, the IC-761, and some
various station accessories.

Last spring I bought the IC-735 for $250.  Yes, a smoking deal for a
rig with smoked finals.  After about 8 hours of (my) labor and about
$125 in parts, I had it back in perfect working order.

My original intent was to run mobile with the 735, but in actuality the
radio was spending most of its time on the garage shelf.  After all, I
had the TS-850S in the shack, which was still working as good as ever.
A friend of mine had recently bought another used 735 and he offered to
sell me the internal keyer and 500 hz CW filter.  I took him up on
these and performed the double open-heart surgery in my shack.  My 735
was now looking better-than-ever with almost a full compliment of
internal options (only the CTCSS board was missing).

In the meantime, I also happened upon a great deal on the ICOM AH-2
antenna tuner for the 735 and so now I had a really great mobile
setup.  A couple of trips into the mountain country with the setup
using tree supported random wires confirmed this.  It was a dream setup
for carefree portable operation.  A really good performer which worked
on all bands from 160 thru 10.

Now, for the life of me I can't explain why I became fixated on the
Kenwood TS-940S.  For some unexplained reason I decided to sell the
complete IC-735 setup and invest in a TS-940.  I had always wanted a
"real" base rig, one with a built in power supply and one which at one
time represented an absolute top-of-the-line radio.  It had alwas been
my belief that this category was best typified by the 940 since it was
in fact the best Kenwood offered for several years, and, it was an
excellent value on the used market at $1200 to $1400 depending on
accessories and condition.

Well, I finally found one, in typical "mint" condition with service
manual and original box for $1250.  Along with this came the promise of
the "Giehl Modification" which was due in the mail.  I eagerly took the
unit home and set it up in the space previously occupied by the TS-850,
which now moved into the standby position.  It was nice that all the
plugs and cables fit, and I was able to go on the air almost
immediately in all modes (CW, SSB, (FSK) RTTY, AMTOR, and Packet).

My first impressions of the 940 were mixed.  Without question I had
purchased one of the best sounding SSB radios that I'd ever owned.  On
both transmit and receive, the SSB performance was outstanding.  CW, on
the other hand, was not so spectacular.  I had removed the 500Hz
filters from the TS850 (being glad they were the plug-in type!) and put
them into the 940.  Almost everyone before had said that the 940 really
didn't need 500Hz filters since the dual-slope tuning worked so well.
BAH!  Only an SSB op would say such a thing!  The fact was that the
500Hz filters were so superior that they made the difference of several
S-units on receive.  Unfortunately, the 940's tuning step size was
never meant for CW.  At 10KHz per knob revolution and with the 500Hz
filters turned on, you could easily roll by 4 or 5 QSO's with a quarter
inch turn of the knob.  Being used to the 850's 1KHz/rev FINE option, I
was immediately disappointed.

The 940 was designed back when memory was expensive and consequently it
didn't have very much offering only 40 memory channels.  Worse than the
lack of memory, however, was its horrible user interface for memory
operations.  Only 10 memories were available on the front panel, with a
slide switch on top for the other 3 banks of ten.  A real setback when
one's been used to the TS-850.

There were quite a few things I liked about the 940. As I mentioned
above, the SSB was fantastic.  The slope tuning worked well (except
when the 500Hz filters were engaged), and the audio peak filter was a
nice touch on CW.  I didn't think much of the antenna tuner, however,
since it was only semi-automatic.  Worked OK, however, giving me 8 band
coverage on my Butternut HF6V.  Nevertheless, it was only about 3 days
before I put the TS-850 back on line (and re-installed the 500Hz
filters), and moved the 940 over to the "standby" position.

Shortly thereafter, and almost by miracle, two or three guys checked
into the local swap net advertising wants for a TS-940.  I called a
couple and soon had some interest coming my way.  Meanwhile, the Giehl
mod came in and I spent part of an evening installing it.  The Giehl
mod is a new EPROM for the TS-940 which reprograms some of its
features.  I highly recommend it to any present or future 940 owner
since it really improves the memory user interface.  With the mod
installed, you get tunable memories, variable tuning dial speeds, and
access to all 40 memories from the front panel.  The old 4 position
slide switch on top is now used to select from tuning rates of 1/2/5/10
KHz/rev, which was a VERY nice option.  Now the 940 had a reasonable
tuning speed.  The mod (which is advertised in QST, and CQ) costs $50.
Hats off to Mr.  Giehl for reverse engineering the 940's Z-80
firmware!  Boy, what I wouldn't give for a crack at it myself if I had
the time...

The very next day after installing the Giehl mod I sold the radio.
That same evening, I bought a nice IC-761 which had also been
advertised on the local swap net.  Again, I managed to get a good deal
and ended up not having to pay any more than what I got for the 940.

I'd heard several bad things about the 761, with some folks saying that
it was "crap" and that the 765 was the only way to go.  To top it off,
there was a QST review which had a few negative points as well.  Days
before I acquired the rig, I had carefully read the QST reviews on both
the 761 and the 765 and had contacted some of the people responsible
for reviewing them.  I quickly reached the conclusion that the 761 and
the 765 were essentially the same rig with the 765 having mostly a
better user interface, more memories and a new synthesizer design.  The
receiver performance specs (I had both brochures too), were nearly
identical.

One of QST's complaints about the 761 was that the synthesizer did not
lock up fast enough when operating split frequency QSK CW.  It had
pointed out that if your split was greater than 30KHz that the signal
would begin to sound chirpy due to the transmitter keying up before the
synthesizer went into full lock.  Hmmm, I thought, now when if ever
have I ever worked split QSK CW????.  Since the total of that
calculation came to less than one, I decided that this wasn't a factor
for me.

One 765 reviewer's statement stuck in my mind.  It had said
(paraphrased) "the 765 is one of the 5 best receivers that had ever
been tested in the [QST] lab".  Knowing this, and knowing that the 761
was indeed very much the same as the 765, I decided to go for it.

Although I didn't expect it, I fell in love with the IC-761
immediately.  It had a smooth 2.5KHz/rev tuning rate, built-in 500Hz
filters, a standard TCXO, built-in CW keyer, a wonderfully bright
display, a very fast automatic antenna tuner, a spacious and
uncluttered front panel, and it _sounded_ great too!  It also put out
in excess of 120 Watts on all bands, and the previous owner had
indicated that when he received the radio it had put out 160 Watts!  He
told me that he went inside and cranked it back to "save the finals".
I still don't know what the full story is on the power output (it's
only rated for 100W), but everything seems to work just fine.

To be objective in looking at the 761, I have to agree that its memory
interface could have been better.  It does not have band-stacking which
means that when you change bands using the band switch it always plops
you down in a fixed location, typically 40KHz up from the bottom of the
new band.  Newer rigs remember the last used frequency, mode and filter
selection for each band (i.e. the 765, TS-850, et al).  As the previous
owner pointed out to me, however, if you avoid using the band switch
and use the first 9 memories instead, you can easily realize band
stacking by just pressing MEM before you turn the knob.  It's nice too
that each of the 761's memories are tunable, which when used this way
(and if you remember to hit MEM), you have potentially 32 tunable
VFO's.

Another common 761 objection is that it displays only down to 100Hz
whereas the new rigs (765 included) display frequency down to 10Hz.
Well, it's surprising how you can be disappointed by a "feature" which
you really either don't use or need.  Yes, it may be interesting to
know at times that the station that you're tuned to is 40Hz off, but
despite this you're still going to have to tune him.  The fact that
your display shows xxxx.0 or xxxx.04 is irrelevant.  I've decided that
the 761's 100Hz display resolution is more than adequate for my needs.

I've also noticed that in QSK modes (CW, FSC, etc.) you can hear a very
slight relay clicking.  Although it's hardly objectionable, it is much
louder than the TS-850 which is nearly silent in QSK.  I don't know if
this is a linear relay that I'm hearing or if it's something else.  If
it's only a linear amp relay, I'm going to figure out a way to
conditionally disable it using the phono jack labeled "spare" on the
back of the rig.  I did the same thing on my TS-440 and it was very
handy.

Another note about the 761's stock 500Hz filters: they show little or
no insertion loss when used.  Quite a departure from the typical
Kenwood response which I've seen vary from 1 to 4 S-Units when you
switch the filter(s) in.

The 761 now sits proudly in the "main" position with the 850 on "active
standby".  Its now hooked up to two other recent shack additions from
last weekend's hamfest: a Kantronics KAM (mint, w/5.0 for $150), and
the Yaesu YS-60 Watt/SWR Meter (working, good condx, $40).  Next to be
replaced: my Collins 312B-4 Speaker/Wattmeter/Phone Patch - yours for
only $150...

Well, such is life in the AA7BQ shack these days.  I can only hope that
things continue to be as exciting.  Oh, by the way, I was unable to
sell the 735 package (IC-735, AH-2 Tuner, (new) Mobile mounting
bracket, Internal Keyer Option, 500Hz filter) for the $1100 I was
asking (I would have taken $1000).  I was surprised since it
represented an actual $1600 in current prices.  Anyway, I ended up
trading the 735 to my father for a 1978 Volvo which I'm in the process
of selling now... Isn't this a wonderful hobby?  :-) :-)

-fred

-- 
| Fred Lloyd  AA7BQ,  Systems Engineer          Fred.Lloyd@west.sun.com |
| Sun Microsystems Computer Corporation                   ...sun!flloyd |
| Phoenix, AZ    (If it's a fact, I believe it!)         (602) 275-4242 |