SWR meter - A DIY project - Page 3 - RC Groups
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Dec 14, 2011, 12:18 PM
Build Fly Crash Repeat
crezzee's Avatar
If anyone in the UK is building one of these, how about swaping some SMA patch cables in return for a couple of these detector diodes.

http://uk.rs-online.com/web/p/produc...633D4E4F4E4526

PM me if interested
Cheers Ian
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Dec 14, 2011, 12:32 PM
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GregSilver's Avatar
Anyone willing to contribute and make a PCB layout for this?

I might be willing to contribute and CNC the boards for people. I have time to cut about 10-20 boards a week.
Dec 14, 2011, 01:12 PM
Registered User
i think i found the cheapest source for the coupler, but only for 900-1200, at 12 shipped worldwide:

http://www.ebay.com/itm/310209833363...fvi%3D1&_rdc=1
Dec 14, 2011, 03:00 PM
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Too big the price to abandon 5.8Ghz.
Dec 14, 2011, 05:00 PM
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Hugeone's Avatar
Quote:
Originally Posted by Martinba77
I am just wondering now if I found a Dual Directional Coupler for my Frequency, then can I have a double (vF/vR) reading and attach directly into two voltage displayers and have the two numbers simultaneously? And then make a nice wood box and have put toghether nicely inside with the two displays facing outside to the front of the box?
Mmmm, maybe this make no sense at all!

Martin
Yes, it make lot of sense

-Hugo
Dec 14, 2011, 05:30 PM
Registered User
If you are not interested in frequencies above 2.4GHz, than you can make something like this

http://pe2er.nl/wifiswr/

or this

http://www.frars.org.uk/cgi-bin/render.pl?pageid=1085

Nigel.
Dec 15, 2011, 12:44 AM
Registered User
Leszek_K's Avatar
I have built this one : http://pe2er.nl/wifiswr/ with just RF head PCB modified to fit into the square made of 3 SMA panel connectors soldered together. Works great on 5.8GHz too. I think it is not as accurate as power coupler based but good enough for home use.
EDIT: also - I used only 3 OpAmps - didn't use the one with NULL pot on it.
Last edited by Leszek_K; Dec 15, 2011 at 01:06 AM.
Dec 15, 2011, 01:29 AM
Registered User
Any issue if the components are soldered in the air without PCB, if skills permits ?
Dec 15, 2011, 03:22 AM
Registered User
Quote:
Originally Posted by RENATOA
Any issue if the components are soldered in the air without PCB, if skills permits ?
It can be done with good soldering skills...

Dec 15, 2011, 03:34 AM
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Leszek_K's Avatar
Renatoa - I assume your question was directed to me - didn't try that. PCB is double-sided as in a picture. Still needed a little vane capacitor to balance the bridge..
Dec 15, 2011, 03:37 AM
Registered User
Leszek_K's Avatar
Quote:
Originally Posted by Hugeone
Yes, it make lot of sense

-Hugo
In that case it would be easier to add some differential amplifier and show SWR directly.
Dec 15, 2011, 05:34 AM
Registered User
I see that someon use a 50ohm resistor for port 4 ( coupler )....why ?
When you buy a coupler....Isnt port 4 terminated ?


Thanks
Dec 15, 2011, 08:35 AM
Engineer for Christ
IBCrazy's Avatar
@renatoa - You can also build a wheatstone bridge circuit with 3 X 50 Ohm resistors on a PCB board and tap between the measurement junction for the reading. In any case you need a ground plane for reference or the circuit will resonate. So a backed PCB board makes it easy.

-Alex
Dec 15, 2011, 10:41 AM
ELECTRIC R/C
Jsutherland8's Avatar

Mini-HowTo SWR meter - A DIY project


Quote:
Originally Posted by piopio
Is this diode OK for swr-meter ?

http://www.rs-components.co.id/diode..._from_store=id
Thanks
The Max forward voltage is very low for this item.!
Dec 15, 2011, 10:51 AM
Engineer for Christ
IBCrazy's Avatar
^yes it is. It's a Schottky diode. It's supposed to be low. That is the voltage drop when working in the forward mode.

-Alex


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