Author Topic: R&S FSH3 VSWR bridges  (Read 333 times)

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Offline Grubi

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R&S FSH3 VSWR bridges
« on: May 17, 2021, 11:21:25 am »
I was wonder - have you seen FSH-Z3 and FSH-Z2 bridges teardown somewhere?
If one have FSH3 with tracking generator, but missing those bridges - is it possible to make own, external bridge and
still have correct measurement? Spare ones are available from R&S, and from ebay, but on crazy prices.
Even calibration set cost like 700-1000Euro.
I guess for pre-amplifier it will be easier, but for bridges I don't know...

Offline Robert763

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Re: R&S FSH3 VSWR bridges
« Reply #1 on: May 30, 2021, 02:01:51 pm »
There s nothing "special" about the R&S bridges. You can use a directional coupler, return loss bridge or even a hybrid power splitter / coupler. They just have to be 50R and cover the frequency range you are working with. You do of course have to normalise it with a short and 50R load.  I no longer have a FSH3 but when I did I just used a Mini-circuits hybrid for lower frequencies and a HP directional coupler for V/UHF.
Even one of the cheap RLBs on ebay work well. You can put one in a diecast box with N sockets at te righ spacing and use a pair of M-M N couplers to connect it directly to the FSH3.
Even better use a pair of these
and semi rigid coax inside the box to one of these


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