At 02:38 PM 5/17/2010, tosca...@umn.edu wrote: >On May 16 2010, Sebastian wrote: > > > Perhaps others such as DEMI, will see this as an opportunity and come up > > with alternatives? > >Well, keep in mind that DEMI's strength is in transverters, and what is >hard to obtain for satellite operation from most common-place existing >equipment is a full-duplex transceiver. I don't think that DEMI is likely >to start building transceivers, but if you had a true full-duplex >transceiver, they would have transverters available to upgrade the radio to >the satellite bands needed.
Completely doable with current xvtrs. Tell them what frequencies you want. >Here's a thought: buy two SoftRocks for a lot less than the price of the >Flex 5000 -- one would be the v6.3Rx/Tx and the other could be the V9 Rx >only. This would net you two independent receivers and one transmitter, and >with clever wiring, selection of VHF & up transverters, and maybe a little >bit of software development, you could turn that into a software-defined >radio that would be capable of full-duplex cross-band operation. (The V9 Rx >would be the primary receiver, the receiver in the V6.3Rx/Tx would be >"spare" or "extra" or even ignored.) You'd need to configure the >transverters with "split IF" Huh? Why? Put a xvtr for the uplink band on the Tx and another xvtr for the downlink for the Rx. >, and use two coaxial relays to route the 28 >MHz SoftRock IF Rx and Tx separately to the correct receive and transmit >transverters. I thought you had two separate Softrocks, so why the relays? > A bit of innovation/homebrewing would be needed for >convenient band-switching, since you would need to switch two different >transverters into the correct "position" depending on the mode: V/U vs. U/V >vs. V/S vs. U/S vs. L/S vs. L/U vs. whatever other modes you wanted to >support. But 4 transverters (145, 435, 1269, and 2400 MHz) would give you >lots of satellite modes. four xvtrs would give you every conceivable combination of up and down link: V/U, U/V, V/L*, L/V, V/S, S/V, U/L*, L/U, U/S, S/U, L/S, S/L* * These modes are not allowed for Amateur Radio space-coms. If each xvtr was configured for separate Rx and Tx antenna and IF connections the configuration tree would be simpler. I count nine configurations (excluding HF bands). If eighteen coax relays seem a bit much, make a coax patch panel and use coax jumpers to configure for the mode you want. > Oh, don't forget there are some birds with HF >links and the SoftRock can do HF natively too... > >If only I had the time to work on such a thing... > >Ideally, the transverters would be dual frequency, so that you could tune >to 432 terrestrial or 435 satellite; 1269 satellite or 1296 terrestrial; >and 2304 terrestrial or 2400 satellite. With the newest xvtrs using PLL in place of xtal oscillators; this is a dc switch to shift LO's. I am installing PLL's into my 1296 and 3400 DEMI xvtrs. >Newer DEMI transverters with the >synthesized LO board can be configured that way, at least on the higher >bands. Then you'd have not only a ki...@$$ satellite system, but also an >outstanding weak-signal terrestrial system. DEMI is planning for PLL from VHF up (when they can get to it). PLL available now 1296 and up. >Unfortunately, DEMI is once again revamping their lineup of products. Of >course, this is good for us who want the latest and best, but bad for us >who want something right NOW. Prices and specs are a little bit harder to >obtain from DEMI right now, but I expect that the wait will be worth it. Prices are announced on the webpage. Some of the xvtrs are shipping in June (I have 144/28 ordered). They are shipping assembled units first, then will offer kits later in the summer. 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-600w, 432-100w, 1296-60w, 3400-fall 2010 DUBUS Magazine USA Rep dubus...@hotmail.com ====================================== _______________________________________________ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
