[Kenwood] Signal loss through outboard AT

[M. Whiteman]

Dear Group;
I  was in the process of reorganizing my shack when I made a (new to me)
discovery. I had the radio (TS-850) hooked up directly to the antenna
via coax and was listening to the AM broadcast band. I also have a TS-50
& AT-50 as backup and decided to compare the signal loss as more and
more items were added to the 850 coax. The first thing I hooked up was
the monitor scope (SM-230) and observed the signal strength shown on it.
Then came the amp (Ameritron 811)  and watt meter (Daiwa 801H). During
the hooking up process, I did not turn the radio off. I just add more
items and coax. Reception was beautiful (station about 500 miles away)
and always better than the TS-50. The last thing I added was the antenna
tuner (Heathkit SA-2060). The first thing I noticed was that the
broadcast band became silent. No hiss. No snaps. Nothing but silence. At
first I thought that the coax switch was to the wrong port. It wasn't. I
hooked the coax up to the bypass outlet and switched the front to
bypass. AM came back. Switch coax back to coax 1 - AM silent. I placed a
double male connector between the 2 coax end and tried wiggling and
pulling on the cables. AM still being received. Coax is good. Back to
the tuner in coax 1 position - no AM. I replaced the SA-2060 with a
SA-2500 I keep in reserve. Same results as the SA-2060. I have an MFJ
versa Tuner II that just hangs around the place. I hooked it up and in
bypass position, you get AM reception. Through the tuner, nothing. There
is a noticeable difference in weak signal detection (both audibly and
visibly on the scope) all the way up to 17 meters. At 15 and 12, it is
only detectable on the monitor scope but not in audible signal strength
( to my aging ears).
I will be setting up a test to measure the signal strength at the IF
output when I arrange with a VE3 friend to send me a series of CW pulses
at a fixed output  level (at his end) spanning the HF bands. I will be
adding components and see what the signal strength drop is.  It will be
a time consuming process but the results would be interesting.
I am currently running without the tuner in place and it is like owning
a new radio.
Conclusion - Adding an outboard tuner results in a noticeable weaker
signal - the lower the frequency, the greater the loss..
Question - Does anyone know of a way to improve antenna tuner
efficiency? Any tests on tuner efficiency?

Thanks
Mike ZF1MW


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