Espritmodel.com Telemetry Radio
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Old Dec 14, 2011, 05:49 AM
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Australia, WA, Bunbury
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hi where do you get the Directional coupler?

thanks
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Old Dec 14, 2011, 07:14 AM
Always soldering
Joined Dec 2011
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You can buy it from here:
http://www.ebay.com/itm/KRYTAR-1851-...-/400227806617

Or from here only if you are using 5.8gHz:
http://www.ebay.com/itm/MAC-Technolo...item5891333a58

And the Diode here:
http://www.ebay.com/itm/Agilent-Micr...item22f8b9c2fd
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Last edited by Martinba77; Dec 14, 2011 at 07:28 AM.
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Old Dec 14, 2011, 07:19 AM
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I think once you bought the directional coupler and sourced the balance of the parts, you could just buy a SWR meter. Unless you could find the parts pretty cheap you would be close in cost and maybe save some headaches. Just a thought.
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Old Dec 14, 2011, 07:31 AM
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I donīt want to be off-topic but depends on wich frequency you plan to use.
I use 5.8gHz and if you find an VSWR meter for under a 100$ please let me know.
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Old Dec 14, 2011, 07:34 AM
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About capacitor is best ceramic, electrolitic, or tantallium ?


Thanks
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Old Dec 14, 2011, 08:57 AM
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Quote:
Originally Posted by Martinba77 View Post
I donīt want to be off-topic but depends on wich frequency you plan to use.
I use 5.8gHz and if you find an VSWR meter for under a 100$ please let me know.
Your probably right, wasn't thinking of 5.8 ghz. I know you can buy a SWR from fleebay for about $300. Some of the directional couplers I've seen are pretty expensive.
http://www.ebay.com/itm/370523272460
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Old Dec 14, 2011, 09:37 AM
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^ Yeah there are some directional couplers from 400 to 850 euros but I found mine at 49 euros (+ or - 63 $) from 2 to 6 gHz here in Italy. (used)
Try to find it used on Ebay

Cheers
Martin
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Old Dec 14, 2011, 09:58 AM
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seems to be cheaper if you look for lower bandwidth couplers and just get 2 or 3 to cover your needed frequencies
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Old Dec 14, 2011, 10:06 AM
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Quote:
Originally Posted by piopio View Post
About capacitor is best ceramic, electrolitic, or tantallium ?


Thanks
It doesn't really matter. Tantulum and ceramic work great. I use Mylar.

-Alex
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Old Dec 14, 2011, 10:08 AM
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@Martin - Didn't you find a 5.8GHz SWR meter for $1400 or something?

The DIY way is far cheaper than trying to buy one. Not only that, it's more rewarding. Belive it or not, the design in this tutorial is very similar to what's inside that Daiwa meter

-Alex
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Old Dec 14, 2011, 10:20 AM
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SMD directional couplers can be had from Mouser for under USD3, but one would have to be very comfortable working with SMD. And that lets me right out.
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Old Dec 14, 2011, 10:24 AM
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Yes Alex, I found this one here:
http://praxsym.com/t-meter.html

And here is with price:
http://www.moonblinkwifi.com/pd-prax...ds-pm-2458.cfm

And, at least to me, is more rewarding like Alex says.
And maybe I can learn more about this things if I build one and try to use it.
By now my list is about 80 $ and the only things i must buy now are the resistor and the capacitor, maybe 1 or 2 $ more!
And off course, the most beatifull thing: build it! For FREE!

By the way, if someone its not in a harry and canīt find the diode, I buy 10 and i can send a couple for free if someone wants!
But must wait I think, mmmm, about week and a half or two!!!

Cheers
Martin
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Old Dec 14, 2011, 10:40 AM
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Martinba, if you find something interesting about couplers and diodes, we can do a small group buy and combine shipping etc.
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Old Dec 14, 2011, 10:42 AM
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i would ask to ibcrazy, do the short distances between components are an electronically critical part of this SWR? I'm asking because working on a pcb, even small, may be easier
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Old Dec 14, 2011, 10:46 AM
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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
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