[Kenwood] Signal loss through outboard AT

[Larry McKibben]

Hi Mike,

I had a similar problem when testing a hone made portable 10M antenna.  Although
I was using an ICOM-735, The symptom was the same as you stated when an antenna
tuner was inserted.  In the bypass mode, I could hear an AM broadcast station,
but in the tuned mode (tuned for 10M), I couldn't hear any AM station.  I
reasoned that in the tuned position, there was not enough AM signal getting
through.  That is the AM signal was being impeded by the 10M tuning.  I did not
try to tune the tuner for the AM station.  This is my take on it.  Hope it
helps.

Larry



"M. Whiteman" wrote:

> 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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--
Happy Trails....  Larry