On May 17 2010, Edward R Cole wrote: >At 02:38 PM 5/17/2010, tosca...@umn.edu wrote: >> >>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. >Huh? Why? Put a xvtr for the uplink band on the Tx and another xvtr >for the downlink for the Rx.
Because the SoftRock v6.3Rx/Tx is half-duplex only. It receives OR it transmits, but doesn't do both at the same time. So my proposal is that an Rx/Tx unit provides the transmit, and a completely separate Rx only model provides the receive. >>, 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? Not an Rx/Tx relay. What I was imagining (and similar to what I am building myself) uses a single pole, 6-position coaxial SMA relay. For satellite use (full-duplex), the Tx port goes to the common, and the Tx port of 6 different transverters go onto the six selectable ports. The Rx port goes to a second 6-way relay common, and the six poles go to the Rx side of 6 different bands. Six-pole relays are hard to find, you might find it easier to come up with 4- pole relays, but I snatched up a bunch of six-pole relays from eBay a few years back. In fact, i snatched up twice as many as I really wanted at the time, because my regular auction looked to be in jeopardy of losing, so I bid on a Buy-it-now auction, and of course, won both. Four-pole relays would be plenty for V, U, L, and S bands in all legal combinations. In my application for terrestrial use, one 6-pole relay goes to a 10M SDR common, and the 6 poles go to (1) HF, (2) 50 MHz Xvt, (3) 144 MHz Xvt, (4) 222 MHz Xvt, (5) 432 MHz Xvt, (6) to a special 2M-10M intermediate Xvt, which goes to another 6-pole relay, and from there to the 6 higher bands: 902, 1296, 2304, 3456, 5760, and 10368 that all need a 2M IF instead of a 10M IF. >> 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. One 4-pole relay for the Tx side, and one 4-pole relay for the Rx side (well, you only need 3-pole since L-band is not an acceptable downlink) and two rotary switches to select the Rx band and the Tx band would do it. But wouldn't you prefer to be able to just push a button labelled "L/S" and have the Tx and Rx relays switched to the appropriate band positions? That's what I ment with innovation / homebrewing for convenient band switching. >>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. Yeah, I bought one for my 10368 MHz transverter, but haven't gotten around to installing it in place of the MicroLO board. I even have a 10 MHz rubidium standard to lock it onto the correct frequency. More projects than time to work on them! >>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. That's good to know. I realized they were working down the bands in their quest to redesign their transverters to all work with the PLL board. I didn't know that they already had 1269/1296 and 2304/2400 PLL transverter configurations ready. >>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. Per the web site: No prices currently listed for 6M through 70cm bands. "in redevelopment" No PLL models announced for 33cm and 23cm yet. All models from 13cm and higher frequency now listed as PLL models with pricing information. You may have more information than I do on that. I pretty much stay chained to my desk here in the sub-basement most of the day.,. 73 de W0JT _______________________________________________ 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
