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Old May 4th 05, 08:00 PM
Cecil Moore
 
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John Smith wrote:
I wish an indication of SWR which is cheap, uses fewest parts possible, and
has the possibility of "automatic operation" and one can be placed on each
and every antenna I am playing with (or anything else, maybe one on the bird
fountain! grin)...


Got just the device for you on page 520 of "The radio amateur's
handbook", 1957 by the ARRL. It's called the "twin-lamp" and
consists of a piece of 300 ohm twinlead and two flashlight bulbs.
I used one in 1957 on my all-band off-center-fed dipole. I ran
40 watts on 11m in those days. :-)

You might want to take a look at another type of design for SWR
meters. There is one that uses a short piece of slotted line
with two parallel conductors that separate the forward and
reflected components without phasor addition/subtraction.
Here's a schematic of the Heathkit HM-11 SWR meter.

http://www.qsl.net/kb7rgg/heath/sche...chema_hm11.gif

Note the low component count. The only tricky part is the slotted
line but that is a mechanical problem, not an electronics problem.
Resistors R1 and R2 attenuate one wave in one direction leaving the
other wave in the other direction to be rectified by d1 and d2.
--
73, Cecil http://www.qsl.net/w5dxp

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