November 2006 - AMSAT-BB - mailman.amsat.org

Re: Relative merits power divider vs power divider/combiner
by Scott Townley 22 Nov '06

22 Nov '06

As long as all ports are terminated properly, they both are reciprocal devices--they work the same on RX as they do on TX. If ports are mismatched, different things happen between A and B (and that's true for both RX and TX) Device A will show mismatched impedances at all other ports, and may no longer evenly divide power. Device B will show no mismatch at the 3 input/output ports, but power will be dissipated in the port 4 load. Note that a properly designed Device A will not be mismatched on RX at the split ports. The main advantage of Device B is the relaxation of the requirements of precise impedance control. -- Scott Townley NX7U Gilbert, AZ DM43di ---- Joop & Tineke Verdoes <joop.verdoes(a)nameplanet.com> wrote: > OM-s > As I got so much truely valuable and usable feedback on my hybrid power > divider/combiner questions, I now dare to ask the following. > > For making circulary polarised yagis one needs to split 'things' over > two yagis > There are basically two ways to split power > A- use a 36 ohm power splitter, often a piece of waveguide with one > connector on one end(for the TRX) and two connectors (for the Yagis) on > the other end > B- use a 70 (75) ohm hybrid power splitter/divider, which has 4 ports, > one extra for a terminator. The TRX sees just 50Ohm. > > A- and B- are both fine for SPLITTING power. In both cases the TRX sees > 50ohm, although there are two 50ohm connected in parallel and the other > side of the divider. So both are fine for transmit. > > But...... > A- Is ONLY a power splitter seen from the transmitter's side, it does > present a mis-match as seen from the yagi, so on receive things are less > than optimal > B- Does work both ways, it presents a nice 50ohm port to the yagi, but > the RX signal is split between the RX and the other yagi, so the signal > that goes to the RX is 3db down. > > Does anybody have a view on how "bad" A- is vs B-? > > Have fun > Joop, PA1JAV > > > _______________________________________________ > Sent via AMSAT-BB(a)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

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Re: Alliant rotor U100
by ehekman＠cox.net 22 Nov '06

22 Nov '06

Norman, Bob, WB4APR, and Greg, KO6TH, and Dave, K8DAV have written articles about interfacing the U-100 type rotors to the PC. A couple of the links are shown below. I started implementing Greg's method with a rotor controller circuit designed by Mark, WA8SME, using a Basic Stamp module but haven't finished it yet. I would be happy to share some ideas off the list. http://home.jps.net/~gregd/hamsite.htm http://www.k8dav.com/u100_info.htm Ed WB6YTE

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Re: Alliant rotor U100
by WILLIAMS MICHAEL 22 Nov '06

22 Nov '06

I am using a U-100. My LVB tracker only controls the azimuth which is an old Wilson WR-500 that I upgraded. I normally adjust elevation only a few times through a pass. It's easy to glance at the pass data displayed on the monitor and see if elevation needs to be bumped up or down. According to the Sep/Oct AMSAT journal, 81% of AO-51 passes are uner 49 degrees. Thanks, I will look at the web-sites for U-100/110 auto control. Is there anyone out there that has built the 1.2 / 2.4 swr bridge from the 2000 Sep/Oct issue of AMSAT journal? 73, Mike K9QHO AMSAT 33589

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Tracking board
by Norman W Osborne VE3CJE 22 Nov '06

22 Nov '06

Any one out there willing to part with hardware to control the U-100 rotors. Just thought I would ask before I begin collecting parts for construction. Norman.

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SuitSat 2
by Reicher, James 21 Nov '06

21 Nov '06

Hey all, has no one heard the announcement about SuitSat-2??? http://newsvc.cq-amateur-radio.com 73 de N8AU, Jim in Raymore, MO

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Sat-El
by Norman W Osborne VE3CJE 21 Nov '06

21 Nov '06

Anyone know of this company, Sat-El in California. I understand they used to sell a tracking board for U-100. Norman.

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Re: Question about tuning for doppler and SatPC32
by ehekman＠cox.net 21 Nov '06

21 Nov '06

Roger, That is an explanation I can appreciate. The TS-2000 is a fabulous radio with many more features than I will ever use but the pleasure of operating a recently acquired Hallicrafters SR-150 has my focus for now. Also, after 39 years of ham radio operation I am still determined to get my CW proficiency up so I can enjoy QSOs on one of my homebuilt qrp rigs running 250 mw. I think my logbook will show the first satellite contact with the TS-2000 was on CW and I am always happy to respond to CW on the sats. I know this issue has been beat to death but the problem here is that we do experience some interference in the limited satellite bandwidth due to lack of coordination of tuning practices. I would still recommend using Doppler correction on the uplink to minimize interference and so other operators have the choice to use Doppler correction on the downlink. For those that have radios without computer control capability I don't mind following their downlink signal manually. I would never advise them to buy a new radio since I wouldn't want the cost of equipment to keep anyone off the sats as it did for me until this year. Ed WB6YTE ---- RogerKola(a)aol.com wrote: > > Hi Ed.... > > Just speaking for some of us Luddites, the thrill and challenge of a "pure" > QSO, maybe with just CW, is part of the experience. I suppose I could get my > computer to run consecutive QSOs, doppler tune, voice track, log, post my log in > LOTW etc, but that is not what I enjoy. > > My opinion is that "I did it myself" applies to computer "programming," and > to satellite operation seperately. > > I will reward you on your accomplishments, but reserve the right to set my > own goals. > > That said...anyone want to try AM through AO-7? hihi > > Roger > WA1KAT

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Re: Question about tuning for doppler and SatPC32
by ehekman＠cox.net 21 Nov '06

21 Nov '06

I have found it much easier to maintain QSOs when both stations use computer controlled Doppler correction on both links. The downlink frequency errors are easily tracked with the receiver RIT control. It seems to me that the best practice out of courtesy to others is to always use Doppler correction on the uplink. If that is done then the uplink and downlinks frequencies stay nearly constant at the satellite and the receiving station can follow the signal with computer control and very minor RIT adjustments. If uplink Doppler correction is not used then receiving stations must manually track the downlink frequency. Since I have found it easy to implement and it makes QSOs much easier to maintain I am curious why computer controlled Doppler correction is not used by all stations. Are there some radios still in use that do not have the capability for computer control? Ed WB6YTE

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Re: Comparison Quadrifiar verses TMP ll
by k5oe＠aol.com 21 Nov '06

21 Nov '06

Norman, The TPM II is a low-gain beam antenna (2 element, about 6 dBi) using a full wave loop for the driven element. It requires an azimuth rotator to be effective, but because of its low gain does not need an elevation rotator. It can be configured with a coaxial relay for switching polarity (not required). I found this extra feature invaluable for the LEOs like AO-27, UO-14, and FO-20. I have not had them up since AO-51 and SO-50 have been in orbit, so cannot comment on the current need for polarity switching except that AO-51 in mode V/U does seem to "swirl" like UO-14 when I worked it mobile/portable with a hand-held Yagi antenna. A QHA is an omnidirectional antenna with a circularly polarized pattern that is generally superior to that of eggbeaters (their patterns are linear at the horizon, only circular overhead and mixed in between). Another choice in omni antennas is AA2TX's parasitic Lindenblad antenna presented at this year's AMSAT Symposium in San Francisco. Getting a copy of the proceedings is worth it just to see this innovative design. A beam antenna, like the TPM II, will always be superior to an omnidirectional antenna. The beam needs a rotator and the omni needs a preamp (at the antenna) to be effective. If you go with a larger beam, anything more than 3 or 4 elements, you will likely need an elevation rotor as well, but this is a configuration more suited to HEOs than LEOs. 73, Jerry, M0GOE ----- Original Message ----- From: "Norman W Osborne VE3CJE" <nwosborne(a)shaw.ca> To: <amsat-bb(a)amsat.org> Sent: Friday, November 17, 2006 5:09 PM Subject: [amsat-bb] Comparison Quadrifiar verses TMP ll > Just wondering, how the comparison of Texas Potato Mashers ll verses the > Quadrifilar Helix > for Leo's. Both with the ability to switch RHCP and LHCP > > Norman. ________________________________________________________________________ Check out the new AOL. Most comprehensive set of free safety and security tools, free access to millions of high-quality videos from across the web, free AOL Mail and more.

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Re: Question about tuning for doppler and SatPC32
by RogerKola＠aol.com 21 Nov '06

21 Nov '06

Funny you should ask... I just downloaded QuikTrak 5.02 For IBM-PC and compatibles. (Requires DOS 3.0 or later) from the AMSAT website which gives equatorial crossing times for my IBM 8086 Luggable but I'm having trouble getting it to run on Windows 2.0...as for the Oscar Locator...a fine ham on the left coast can set you up for a donation to AMSAT. Now to get back to keying the mic on my Cleg FM27B... ;-) Roger WA1KAT

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