Alan, I know of what you speak. I just wanted to make three points in my
previous post to the list:

1.	SWR readings at the transceiver approaching 2 to 1 are not good.

2.	Solid state transceivers, like the TS590, are designed to
automatically reduce power as the SWR goes above 2 to 1 to protect the
output circuit of the rig

3.	SWR readings at the point of the transceiver, even if they are 1 to
1 are not indicative of what the SWR is at the point where the feedline
connects to the antenna

Your technique for reading the SWR at the feedpoint of the antenna itself is
excellent. However, I suspect very few people on this list have TDR's and
network analyzers. I just wanted to let people know that SWR readings at the
transceiver are very misleading.

As an aside note, many, many years ago I actually burned up the final tank
circuit in a DX-40 because of high SWR. It caused the tank coil and the form
on which it was wound to get so hot that it shorted out, taking with it the
by-pass capacitor, RF choke and the power supply! What a mess!  That was the
days of the PI network, dipping and loading, etc. to tune the transmitter.
Those were some of the good ol' days! <Smile>

Ron, K8HSY
    


-----Original Message-----
From: Alan R. Downing [mailto:[log in to unmask]] 
Sent: Sunday, August 04, 2013 10:22 AM
To: [log in to unmask]
Subject: RE: About SWR...

Hello Ron,  

Actually, you can read the SWR at the far end of the feed line where it
connects to the antenna.  You use a network analyzer and a TDR(time domain
reflectometer).  What I do is disconnect the coax from the antenna and
attach a calibrated 50 ohm load.  At that point, you make your readings.
You then disconnect the load, and reconnect the feed line to the antenna.
At that point, you make another reading.  I am simplifying this a bit, but I
am including the basic procedure.  I generally also make a reading of the
antenna itself, just to confirm that the antenna looks good.  If you suspect
that you have a problem with your feed line, a TDR will tell you precisely
where the problem is located.  TDR's and network analyzers are very handy
pieces of test equipment.

73


Alan R. Downing
Phoenix, AZ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Dr. Ronald E. Milliman
Sent: Sunday, August 04, 2013 7:59 AM
To: [log in to unmask]
Subject: About SWR...

I am fascinated with some of the SWR levels I am reading about on this list.
Any SWR approaching 2 to 1 is not good. In fact, all of the solid state rigs
are designed to automatically cut back the power with higher SWR. Most of
the rigs start reducing power with SWR of 2 to 1 and higher. Further, even a
SWR reading of 1 to 1 is at the point of where the coax or feedline connects
to your rig, and is not an indication of the SWR at the point where the
feedline connects to your antenna. 

Quite some time ago, I provided an article that discusses SWR in
considerable detail. Several of you asked for a copy, and I sent it out to
you, but if you didn't get a copy and want one, let me know, and I'll send
it to you.

Ron, K8HSY