Re: IC-706 and TS-50S on QRP


From: Robert J. Gobrick (
Date: Sat Nov 25 1995 - 08:08:50 EST

Hi Hank and QRP-L gang,

Just some of my own personal notes on using the IC-706 vs the TS-50S for cw
QRP work. I owned the TS-50S for a few months when it first came out but
was very disappointed with the performance on CW. That unit is a dual
conversion superhet and the second IF was at 455 KHz. I experienced a lot
of blow by in SSB (also verified by others) since they used a cheap ceramic
filter at 455 as the only real if filter. Also even with the optional 6
pole cw 500 Hz crystal filter I still found the unit unpleasant to use (AGC
pumping, IF blowby etc). These problems were mainly manifested using a
decent home QTH antenna (I'm told that when you used an inefficient mobile
antenna it was not as great a problem - good way to judge a rig - just use a
poor antenna - hi). Anyway my thoughts were that the dual conversion and
455 KHz IF just didn't cut it for me on the Kenwood TS-50S. I sold the rig
after two months. By the way the new Alinco uses the same dual conversion
line up with a 455 KHz second IF.

Now the Icom Ic-706. I have been quite pleasantly surprised by the Icom.
The Icom is also dual conversion (as is just about ALL the lower priced rigs
now-a days - FT-890/900, etc) BUT it uses a 9 MHz second IF. On SSB etc the
rig comes equipped with the standard 6 pole ssb crystal filter which works a
lot better than any $2 ceramic filter (you know - the kind they use in the
TS-950SAT). I also bought the optional 6 pole narrow 250 Hz CW 9 MHz filter
and it works great on CW and the digital modes (IC-706 has true FSK). The
bottom line is that I find "listening" to the IC-706 on ssb and cw a lot
more pleasant. I also don't have the AGC and blowby problems that I had
with the TS-50S but that doesn't mean that the switchable rf pre-amp and
anttenuator doesn't come in handy when a STRONG bc station on the 40 meter
novice cw band does a job on the poor weak cw signal.

Going back to your power dissipation figures - yes I don't see either of
these rigs as a "power mite" competitor to the Wilderness Radio Norcal 40 or
Small Wonders Lab 40 which draw a few tens of milliamps on receive. I
suspected the IC-706 drew more power since there are SO MANY more bells and
whistles in the IC-706 over the TS-50S. You really need to consider these
heavily computerized rigs for home and mobile use.

Anyway, bottom line is that the new Icom IC-706 is one heck of a rig and is
more than quite suitable for QRP contesting with the 250 Hz cw filter. By
the way the next issue of QQ may have a write-up on the IC-706 from a QRPers
point of view.

Thanks for your power measurements Hank - I have filed them away in my paper
file (I still like hard copies of stuff - hi).

73/72 Bob VO1DRB/WA6ERB

At 10:27 AM 11/24/95 EST, you wrote:
>In October Dave, WB0GAZ, wrote his observations on the Icom IC-706 regarding
>current draw for various operating conditions. I have added the TS-50S to
>Daves findings. The TS-50S was tested with a sealed Panasonic led acid
>12.64 volts, that came out of a uninterruptable power system at one of my
>(used to be customers, but the word for the year is client now!).
> IC-706 TS-50S
>Unit turned off 4 ma 9.8 ma
>Turned on, receive, quiet 1570 ma 890 ma
>Turned on, receive, loud 1650 ma 900 ma
>Transmit, PTT engaged, key up 3700 ma 1730 ma
>Transmit, key down (5W out) 6900 ma ~4000 ma according to Smitty, NA5K
>Transmit, key down (950 mw out) 3050 ma
>Like the IC-706, the TS-50S is not a real RF efficient radio, power in vs. out,
>but it is a decent, small radio. Unlike the IC-706, I have not noticed the
>on the TS-50 drop when it is fed into a higher SWR.
>With the TS-50S there are two filter choices - wide and narrow! SSB-wide
>and the
>optional 500 hz filter. Not bad for general operating, but definately not a
>"big time contest" radio, although it did fine in last June's Field Day with a
>Timewave DSP-9+. The only thing I feel is missing from the TS-50S is a notch,
>but when the DSP-9+ is in line, it doesn't seem to be too bad.
>Haven't seen any reports on the little Alinco HF radio, but I'd expect that
>it is
>in the same basic class with the 50 and the 706 - cute little radio for
>mobile and
>portable, but it's not an cost or features!
>73 Hank K8DD
>*/ Hank Kohl K8DD
| Bob Gobrick VO1DRB/WA6ERB/VE2DRB Newfoundland, Canada |
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