Joeseph wrote:


This is a very screwy problem. First lets get the set-up of my
radio equipment;

The amp puts out about 100 watts on HF.

RADIO-----2 TRANSISTOR AMP-----SWR METER------ ANTENNA

Note the SWR meter comes AFTER the 2 transistor amp.

Ok, when I check the SWR on my antenna it shows 1.1. When I turn the
amp on it shows over 3.x SWR. The antenna is rated at 5 KW. The amp
only puts out about 100 watts.

Hmmm.....Ok lets see what happens when I use my 1 KW oil filled dummy
load.


RADIO----- 2 TRANSISTOR AMP----SWR METER-------1 KW DUMMY LOAD

Same thing. The SWR is about 1.5 in to the dummy load, but as soon as
I turn the amp on the SWR meter shows 3.x plus.

Ok, Maybe my SWR meter is screwy, so lets use my Dentron MT3000
tuner with a built in 200 watt dry dummy load and built in SWR meter.


RADIO ----2 TRANSISTOR AMP----DENTRON MT3000

Same thing. The SWR is low without the amp on and goes high when the
amp gets turned on.


Ok, Lets see what happens when I use my Drake L-4B amp instead of the
2 transistor amp.


RADIO-----Drake L-4B-----SWR METER-------Dummy load

Now the SWR stays low when I turn on the Drake L-4B for both the 1 KW
dummy load and the external antenna.

The transistor uses MRF455 transistors. Why would the SWR meter go up
significantly when I turn on the 2 transisor amp, but stay low when I
turn on a Drake L-4B.

I've duplicated this scenario with three different SWR meters, and
different patch cables. Lets me say for the record the SWR meter
comes after the amp, so I'm not looking at a high SWR on the input
side of the amp. This is on the output side of the amp.

?????




Check the frequency (or frequencies) coming out of the amplifier. I will bet
that what comes out is not equal to what goes in. The antenna is not a
good match for those other frequencies.

Bill k7NOM