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HF/VHF spyverter and RTL

Posted: Wed Dec 26, 2018 11:56 am
by grafter
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?

Re: HF/VHF spyverter and RTL

Posted: Wed Dec 26, 2018 4:11 pm
by dlritter
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

Re: HF/VHF spyverter and RTL

Posted: Wed Dec 26, 2018 8:51 pm
by grafter
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.

Re: HF/VHF spyverter and RTL

Posted: Thu Dec 27, 2018 5:00 pm
by hotpaw2
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.

Re: HF/VHF spyverter and RTL

Posted: Sun Dec 30, 2018 11:21 am
by grafter
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.