Author Topic: Rigol DSA815 - VSWR-Bridge tear down...  (Read 9929 times)

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Offline seahood

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Rigol DSA815 - VSWR-Bridge tear down...
« on: February 05, 2014, 07:33:48 pm »
Hello,
does anybody know what exactly is inside the Rigol VSWR Bridge VB1020 for the DSA815 Spectrum Analyzer ?

http://www.batronix.com/pdf/Rigol/UserGuide/VB1020_VB1030_Manual.pdf
« Last Edit: February 05, 2014, 07:35:27 pm by seahood »
 

Offline KJDS

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #1 on: February 05, 2014, 08:18:26 pm »
It's almost certainly a wheatstone bridge autotester, some intro reading here

http://www.anritsu.com/en-US/Products-Solutions/Solution/Understanding-directivity.aspx





Offline seahood

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #2 on: February 05, 2014, 08:32:02 pm »
Nice ! I ask me how hard it is to build such a device... studying details... --> No Details about the inner organs of the device...
« Last Edit: February 05, 2014, 08:34:29 pm by seahood »
 

Offline babysitter

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #3 on: February 05, 2014, 08:43:59 pm »
Hello Seahood,

you can expect either a wheatstone bridge with some details for RF around (a kind of transformer), googling for "return loss bridge" will shed light on this.


The other possibility is that it is a "directional coupler", just google for it. This is composed normally of 2 transmission lines close to each other and some impedance magic.

Lots of literature about it in ham radio websites and fora available, also "DIY" manuals.
Expect to get some Ferrite parts, thin semi rigid line, "tuner box" enclosures and devastating results when you go for BNC or PL connectors :)

I was willing to measure VSWR too, but I decided for a Oletron RK1413 directional coupler. Good enough for amateur radio use.
~$30 in germany is quite good compared to the rigol thingy and is a good match to the not-too-perfect DSA815.

I'm not a feature, I'm a bug! ARC DG3HDA
 

Offline seahood

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #4 on: February 05, 2014, 08:49:51 pm »
Ok, things are now clearer. But why does this things coast 500$ ? I cannot find any information about the "Oletron RK1413" via an internet recherche.

http://www.ve2azx.net/technical/RLBridges.pdf
 

Offline babysitter

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #5 on: February 05, 2014, 09:46:22 pm »
Olektron, my fault. Available on e-Gay ;D sometimes, or at the german surplus dealer "Helmut Singer".
I'm not a feature, I'm a bug! ARC DG3HDA
 

Offline seahood

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #6 on: February 05, 2014, 10:31:22 pm »
There is a difference between a directional coupler and an VSWR bridge !
 

Offline KJDS

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #7 on: February 05, 2014, 10:58:33 pm »
A directional coupler is inherently a narrowband device and it's hard work to make it broadband.

A bridge is inherently a broadband device but it's hard work to make it work well at UHF and beyond.

Offline iDevice

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #8 on: February 06, 2014, 07:43:59 am »
Ok, things are now clearer. But why does this things coast 500$ ? I cannot find any information about the "Oletron RK1413" via an internet recherche.

http://www.ve2azx.net/technical/RLBridges.pdf
The bridge costs only 150$.
500$ is only for the license and once licensed the DSA815-TG can use any VSWR bridge.
But Rigol sells a package with both the license and the bridge for 650$ which places the bridge at 150$
 

Offline seahood

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #9 on: February 06, 2014, 07:45:33 am »
If i search by eBay i will found only bridgets for 500$, i dont see any bridge for 150$ anywhere.
 

Offline Rory

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Offline iDevice

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #11 on: February 06, 2014, 08:55:58 am »
If i search by eBay i will found only bridgets for 500$, i dont see any bridge for 150$ anywhere.
I guess you didn't read my post...
 

Offline hammy

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #12 on: February 06, 2014, 09:05:13 am »
Get a "Mini Circuits ZFDC-20-5+" Coupler. Works fine.
 

Offline seahood

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Re: Rigol DSA815 - VSWR-Bridge tear down...
« Reply #13 on: February 06, 2014, 09:10:25 am »
@iDevice --> Sorry, i searched for VSWR bridges on eBay instead for return loss briges.

i have fist to study the background... i will try it out. Here is a Video for the proposed configuration -->

« Last Edit: February 06, 2014, 10:50:55 am by seahood »
 


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