That reminds me about an interesting incident with a MFJ antenna analyzer.
Our club had just put up an new 2 meter repeater antenna. They had made
some adjustments to it in one of the member's back yard with it on a short
mast. When they took it to the site and installed it the MFJ analyzer was
pegged indicating a very high SWR. They were at a loss as to what had gone
wrong with the antenna. After hearing about their problem I informed them
that there were some high power pager antennas only a few hundred feet
away. I suggested that they check it again with a real swr/power meter. The
problem was that the antenna was picking up the 150 MHz signals from the
near by paging transmitters, and since there was more power flow from the
antenna to the analyzer than the in the forward direction the analyzer
thought the was SWR greater than infinity to one.
73
Bill wa4lav
At 11:38 PM 4/18/2006 +0200, PA3DUV wrote:
>Is the MFJ analyzer still ok?
>Mine went bust after 3 months, could not handle strong RF radiation even
>when off and not coupled to any circuit.
>I trashed it and purchased a Palstar ZM30. In use now for 2 years, no
>problems.
>Cheers, Dick
>PA3DUV
>
>
>----- Original Message -----
>From: "Partain, Chuck" <Chuck_Partain@maxtor.com>
>To: <amps@contesting.com>
>Sent: Tuesday, April 18, 2006 11:21 PM
>Subject: [Amps] working backwards to setup tank
>
>
> > in ref to my gu-84b based hf amp
> >
> > I set this tank circuit up and tuned at 7.250mhz, came up with a beautiful
> > output
> > then tried to do the reverse check. I put a 2k resistor from the plate to
> > ground, hooked
> > the MFJ analizer up using the settings previously obtained and for th e
> > life of me cannot find
> > a good resistive value to make the swr analizer 1:1 swr or close. I used a
> > 15k pot and even went SLOWLY
> > one end to the other and best I see is 3 to one!!! what am I doing wrong??
> > I used a 2k load to get CLOSE
> > to where I want to set the plate and load caps and the inductance was
> > setup using a formula with 2100 ohms
> > plate reactance. Once running, I went to 500 watts and am using those
> > settings.
> >
> > sorry if I am not clear but maybe someone understands my drivel :)
> >
> > ka1mwp
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
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