HF/VHF spyverter and RTL

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grafter
Posts: 6
Joined: Tue May 01, 2018 5:11 pm

HF/VHF spyverter and RTL

Post by grafter » Wed Dec 26, 2018 11:56 am

I have an RTL v3 for VHF and I've been tempted by the direct sampling of HF so I've got a magnetic loop for HF listening and intend to buy a Spyverter.

Using an RTL for both HF and VHF must be quite common but has anyone devised an elegant solution for switching antennas and/or an upconverter in and out of line?

The most simple method is to use a manual two way switch with the spyverter connected to one side with my VHF colinear on the other side and add a bias T injector between the switch and the spyverter. I think I could do away with the need for an external bias T circuit by creating batch files for two copies of Sharp, one that toggles the RTL bias T on for HF, the other that turns it off for VHF work but I still need to manually control the switch.

I've found this remote antenna switch on Ebay https://www.ebay.co.uk/itm/261767543884 which could be used but how to get the software controlling it?

dlritter
Posts: 42
Joined: Mon Nov 23, 2015 1:08 am

Re: HF/VHF spyverter and RTL

Post by dlritter » Wed Dec 26, 2018 4:11 pm

The Nooelec Ham-It-Up up-converter provides a pass-thru switch which leaves you just needing a normal antenna switch.
Otherwise I bet one could use an old TV A/B switch with F-SMA adaptors

grafter
Posts: 6
Joined: Tue May 01, 2018 5:11 pm

Re: HF/VHF spyverter and RTL

Post by grafter » Wed Dec 26, 2018 8:51 pm

It's a shame the ham-it-up doesn't have seperate antenna inputs that are toggled with the bypass switch, I could live with that but I'm not sure there's much gained with a bypass switch on a single antenna socket. Plus the Sverter includes a case for the same price.

hotpaw2
Posts: 109
Joined: Sat Jan 14, 2017 11:07 pm
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Re: HF/VHF spyverter and RTL

Post by hotpaw2 » Thu Dec 27, 2018 5:00 pm

The easiest (and close to the cheapest, since well-constructed antenna switches seem to be expensive) is to simply use 2 RTL-SDR dongles, one for each antenna.

The only problem might be that the spacing of the USB ports on your computer is too close for side-by-side RTL-SDR dongles, so you'd also need a short USB extension cable or hub. Noo-lec makes some narrower USB dongles, but the one I had burnt-out, possibly because it ran hot. So now I run two RTL-SDR v3's on two different Raspberry Pi's, one for HF, one for VHF.

grafter
Posts: 6
Joined: Tue May 01, 2018 5:11 pm

Re: HF/VHF spyverter and RTL

Post by grafter » Sun Dec 30, 2018 11:21 am

I hadn't even considered that option but given how cheap the RTLs are it does sound like a good plan, thanks for the suggestion. Size isn't a problem because all my SDRs are connected directly to a patch panel of switches and multicouplers to reduce the number of patch leads. I've actually got a couple of very high quality 12v antenna switches, fully shielded and fitted with N sockets that came from a rally, they have neglible loss and very good isolation right up to 2M but I'm stuck for an idea how to control them from a PC for when I'm operating remotely.

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