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Author Topic: SWR meter project advice  (Read 1697 times)
W6AOA
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Posts: 36




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« on: April 08, 2012, 06:47:00 PM »

I have an old collins 312B4 directional swr module and am thinking about using this module with a cross needle meter.  I have a KW homebrew tuner I'd like to incorporate it into.  I'm looking for a circuit that would let me attach the cross needle meter to the FWD and REF outputs of the unit wold like to use two scales. Any assist appreciated..  Ed Schaff  W6AOA
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K9YLI
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Posts: 878




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« Reply #1 on: April 14, 2012, 07:42:18 AM »

 the only thing critical here is the  meter movements.
50 micro amp  or what ever  is needed, then  get  cross needle  meter to  match that.
or  , since this is basically  a  volt meter circuit, use a variable resistor to  determine
a fixed resistor in series with the meter to show proper scaliing.
also then   two resistors and a switch  for the  2 levels of power..

eliminate the  forward reverse switch  and wire each leg to appropriate meter movement.

kind of a  basic    'handbook'    swr circuit.
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W9GB
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Posts: 2659




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« Reply #2 on: April 14, 2012, 08:41:03 AM »

Ed,

There are $17 Chinese cross needle meters (Flashstar in Taiwan) on the open market.
The meters look identical to those used in MFJ, Palstar, and various Eastern Asia mfg.

Part No. SZ-70
Forward meter : 0~10W, Reflected meter : 0~2W
DC 100uA full scale, DCR=1.54KΩ
Meter front size : 72.0x72.0mm, WxH
View window : 64.5x45.5mm, WxH
made by Flash star (SD) co., Taiwan
Dimension drawing : http://www.flashstar.com.tw/showroom.html

--
w9gb
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