Many years ago (~30) I built a simple antenna analyzer consisting of a
passive network of resistors, capacitors and diodes. This was placed
in-line between the TX and the antenna.

The network had 5 DC voltage monitoring points, selected by a 5-way
switch.

Having measured the 5 voltages, you then had to plot on graph paper a
set of circles and lines that were proportional to the voltages -- as I
recall, 3 circles and 2 lines. The point of intersection of the 3
circles was a measure of the R +/- jX components of the antenna
impedance.

I would like to re-create the analyzer, but I can't find the schematic
anywhere. I think I first saw it in a UK ham radio magazine, probably
some time in the 1970s.

Does anyone here remember it and/or can tell me where I can find it?

--
73
Ian, G3NRW

I would like to re-create the analyzer, but I can't find the schematic
anywhere. I think I first saw it in a UK ham radio magazine, probably some
time in the 1970s.

Does anyone here remember it and/or can tell me where I can find it?

--
73
Ian, G3NRW

It may have been published in more than one periodical, but what you're
describing was done by Peter Dodd, G3LDO and Tom lloyd, G3TML and was
presented in our QEX magazine for November 1987 back when QEX was still a
functional experimenters exchange instead of just an added source of revenue
for the League, publishing garbage when that's all they happen to have on
hand.

Contact me off group for help.

W4ZCB

I would like to re-create the analyzer, but I can't find the schematic
anywhere. I think I first saw it in a UK ham radio magazine, probably
some time in the 1970s.

Does anyone here remember it and/or can tell me where I can find it?

--
73
Ian, G3NRW

It may have been published in more than one periodical, but what you're
describing was done by Peter Dodd, G3LDO and Tom lloyd, G3TML and was
presented in our QEX magazine for November 1987 back when QEX was still a
functional experimenters exchange instead of just an added source of
revenue for the League, publishing garbage when that's all they happen to
have on hand.

Contact me off group for help.

W4ZCB
I failed to mention that the original work was done by Doyle Strandlund,
W8CGD and published in QST for June 1965. That may be where you originally
read of it since it's closer to the date you recall. Peter and Tom simply
took the original work and added software Basic programs to solve the
equations mathematically on a Personal Computer. (Two pieces of software are
provided. TomSmall and TomBig. TomSmall will run on a programable pocket
calculator.).

W4ZCB

From: Harold E. Johnson
Date: Sun, 27 Apr 2008 Time: 19:18:12

It may have been published in more than one periodical, but what you're
describing was done by Peter Dodd, G3LDO and Tom lloyd, G3TML and was
presented in our QEX magazine for November 1987 back when QEX was still a
functional experimenters exchange instead of just an added source of revenue
for the League, publishing garbage when that's all they happen to have on
hand.

Contact me off group for help.

W4ZCB

Peter Dodd was the name I was trying to remember. Googling for him gave
me http://web.ukonline.co.uk/g3ldo/aegextra.htm and
http://web.ukonline.co.uk/g3ldo/zsmall.htm. Exactly what I was looking
for.

Isn't the Internet wonderful! Many thanks Harold.

--
73
Ian, G3NRW

Ian Wade wrote:
Many years ago (~30) I built a simple antenna analyzer consisting of a
passive network of resistors, capacitors and diodes. This was placed
in-line between the TX and the antenna.

The network had 5 DC voltage monitoring points, selected by a 5-way switch.

Having measured the 5 voltages, you then had to plot on graph paper a
set of circles and lines that were proportional to the voltages -- as I
recall, 3 circles and 2 lines. The point of intersection of the 3
circles was a measure of the R +/- jX components of the antenna impedance.

I would like to re-create the analyzer, but I can't find the schematic
anywhere. I think I first saw it in a UK ham radio magazine, probably
some time in the 1970s.

Does anyone here remember it and/or can tell me where I can find it?
================================================== ==
Ian , I found the circuit you are after in Peter Dodd's book :
The Antenna Experimenter's Guide ISBN 0 9516024 0 3

The book was published in 1991 by DD Publications
address: 37 The Ridings - East Preston -West Sussex BN16 2TW

British Library Cataloguing in publication Data 621.3824

The description of the analyser can be found on pages 3.9 to 3.22


Frank GM0CSZ / KN6WH

From: Jimmie D
Date: Mon, 28 Apr 2008 Time: 09:49:48

This looks like a really neat device, one of those simple little gadgets
from which you get a huge amount of use.
Hopefully before I got back to work Wednesday I will have one built. Its my
plan to leave out the switch and just bring everything out to test points.


It is indeed a really neat device. I found it very useful back in the
70s, but at that time I didn't have a computer, so had to draw the lines
and circles by hand. After doing this a few times I rapidly lost the
will to live!

The one thing to watch is the input signal level. I used to use the
low-level driver output from the TX, which was fine. But I don't have
that TX any more, so will have to use the low-power output of the
current TX. Some kind of voltage dropper will be needed to keep the
output level low enough, otherwise the analyzer components will fry.

--
73
Ian, G3NRW