[Kenwood] Signal loss through outboard AT

[Steve Stutman]

Hi,

Suggest that "bypass" may short the tuner, but is there a high-pass still
in line?

A properly tuned tuner does not exhibit a great insertion loss on receive
in my experience. But if you are trying to receive out of pass-band it's a
different story.

73,

Steve 

KL7JT/1


On Sat, 2 Mar 2002, 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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