With the advent of rigs like the FLEX-5000, features are becoming available which exist in no traditional rig. However, for operation on VHF, UHF, and microwave frequencies, you are obviously going to need a transverter. Using a 28-30 MHz IF, you can cover 2 meters with 2 LO crystals. However, once you get to 70 cm, it would take 15 crystals to do this. Now admittedly, you wouldn't necessarily want to cover the entire band, as an FT-847, TS-2000, etc do. But you would want more flexibility than just one or two 2 MHz segments for both space and terrestrial operations. More if you wanted to include basic FM repeaters.
Given that there are no (?) transverters which have a 20-30 MHz IF width, has anyone seen a transverter with a tunable IF, instead of crystals? Or alternatively, a VFO-like "VLO" which could be plugged into the transverter crystal socket, or something equivalent? There used to be such VFOs for crystal rigs 3-40 years ago. I doubt that a transverter would maintain full specs over a wide range, but such flexibility would be handy. Perhaps this is a solved problem with the microwave community?
Alan WA4SCA
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Before a mad scientist goes mad, there's probably a time when he's only partially mad. And this is the time when he's going to throw his best parties.
I haven't seen anything other than transverters with 2 switchable crystals. However, one manufacturer has suggested recrystalling for a 24-30 MHz IF.
73,
John KD6OZH
----- Original Message ----- From: "Alan P. Biddle" APBIDDLE@mailaps.org To: "AMSAT-BB" amsat-bb@amsat.org Sent: Tuesday, June 12, 2007 14:47 UTC Subject: [amsat-bb] Full band transverters for satellite operations?
With the advent of rigs like the FLEX-5000, features are becoming available which exist in no traditional rig. However, for operation on VHF, UHF, and microwave frequencies, you are obviously going to need a transverter. Using a 28-30 MHz IF, you can cover 2 meters with 2 LO crystals. However, once you get to 70 cm, it would take 15 crystals to do this. Now admittedly, you wouldn't necessarily want to cover the entire band, as an FT-847, TS-2000, etc do. But you would want more flexibility than just one or two 2 MHz segments for both space and terrestrial operations. More if you wanted to include basic FM repeaters.
Given that there are no (?) transverters which have a 20-30 MHz IF width, has anyone seen a transverter with a tunable IF, instead of crystals? Or alternatively, a VFO-like "VLO" which could be plugged into the transverter crystal socket, or something equivalent? There used to be such VFOs for crystal rigs 3-40 years ago. I doubt that a transverter would maintain full specs over a wide range, but such flexibility would be handy. Perhaps this is a solved problem with the microwave community?
Alan WA4SCA
Before a mad scientist goes mad, there's probably a time when he's only partially mad. And this is the time when he's going to throw his best parties.
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At 12:47 AM 6/13/2007, Alan P. Biddle wrote:
With the advent of rigs like the FLEX-5000, features are becoming available which exist in no traditional rig. However, for operation on VHF, UHF, and microwave frequencies, you are obviously going to need a transverter. Using a 28-30 MHz IF, you can cover 2 meters with 2 LO crystals. However, once you get to 70 cm, it would take 15 crystals to do this. Now admittedly, you wouldn't necessarily want to cover the entire band, as an FT-847, TS-2000, etc do. But you would want more flexibility than just one or two 2 MHz segments for both space and terrestrial operations. More if you wanted to include basic FM repeaters.
Well, as someone else suggested, lowering the IF would give you more bandwidth to play with. Even better, some SDR designs also have the ability to do undersampling, where a narrow (relatively) bandwidth that is much above the sampling rate can be accurately sampled ( conceptually, it's like the sampling is also the first mixer).
It appears that the HPSDR hardware will be capable of undersampling, possibly into the UHF region. I'm hoping to find out for myself later this year when the Mercury and Penelope boards become available. :)
With the right SDR hardware and configuration, transverters may not be needed until you go beyond 70cm.
73 de VK3JED http://vkradio.com
participants (3)
-
Alan P. Biddle -
John B. Stephensen -
Tony Langdon