August 2008 - AMSAT-BB - mailman.amsat.org

re Polarity control box - again
by Angus 06 Aug '08

06 Aug '08

Hi Mak, thanks for reply. The problems occur when we go and try and make the polarity control unit remote controlled. I have a fully working manual unit here in the shack and is 100% fine. However the remote unit I built use's relays to add in extra lengths of 50ohm coax as a delay line (a 1/4 wave on the -45degree yagi, and a 1/2wavelength on the +45degree yagi.) This system I have seen used by very many operators and also some comercial units, however with just the 2 delay lines the LHCP will never really be LHCP, it needs an extra set of relays to switch in the other 1/4wave delay line. I was just wondering if anyone else had seen this or have I just misunderstood the circuit somehow. Any thoughts would be appreaciated. regards Gus M0IKB -- I am using the free version of SPAMfighter for private users. It has removed 1661 spam emails to date. Paying users do not have this message in their emails. Get the free SPAMfighter here: http://www.spamfighter.com/len

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data port rig/tnc cable
by Mr Jeffrey L Ross 06 Aug '08

06 Aug '08

hi folks, well I'm. halfway there in setting up a downlink/uplink data station for sats. So far, a local, way off station can copy me but I can not copy him. Was wondering if my wires are right. heres what i have: tnc:recv. -rig :9600 out tnc:xmit - rig :data in tnc:ptt -rig :ptt tnc:grnd rig:grnd pk 96 - ft 857 sound right? if not please let me know,tks still trying for go-32. /anyone got the status, web aprs page get updated/running yet? kc8gkf

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Re: [!! SPAM] Re: The Journal and "Progress"
by ANTHONY JAPHA 06 Aug '08

06 Aug '08

Hi Bruce, Good to hear from you. The news about P3E completion is very good. If the Mars connection helps to sell it, that's good strategy. What DX have you worked recently? 73, Tony, N2UN > [Original Message] > From: Bruce Robertson <ve9qrp(a)gmail.com> > To: <tjjapha(a)earthlink.net> > Cc: Amsat-Bb <amsat-bb(a)amsat.org> > Date: 8/6/2008 7:34:48 PM > Subject: [!! SPAM] Re: [amsat-bb] The Journal and "Progress" > > On Wed, Aug 6, 2008 at 7:07 PM, ANTHONY JAPHA <tjjapha(a)earthlink.net> wrote: > > Greetings All, > > Just received the May/June Journal. It is extremely disheartening. > > > > For the 2nd issue in a row, there's no status report on Eagle (using the term in the broad sense as W2GPS uses it, to include the possibility of a rideshare). In Rick's Apogee View, there are the most vague references to progress, but the whole piece could have been written long, long ago. No conceivable definition of a progress report would include that writeup. There is not a single specific citation of real progress. We can only assume there has been none. > > > > This criticism has nothing to do with the difficulty in identifying an affordable launch opportunity, the discussion of which has been lengthy here. It has to do with getting ready for a launch if and when it appears possible. At one level, this is a chicken and egg problem; without a specific launch opportunity, what is to be built? But, the way to get out of a chicken and egg situation is to acquire either a chicken or an egg. We have neither. Without a chicken there'll never be an egg, and vice versa. > > > > Let's get a bird basically ready to go, i.e. designed, prototyped, tested, refined, etc. Where are we on these steps? How much more money is needed to get us there? Is the prospect of raising that amount of money good or is it as grim as being able to afford a launch? > > > > I continue to think that there is enough talent here to do the real stuff. That has been demonstrated many times. What there is little evidence of is the capacity to manage the effort in a way that improves the prospects of pulling the pieces (finance, planning, decision making) together. > > > > If I am wrong about all this, then please show the evidence. Just where are we on the many pieces that will comprise the bird? When will they be finished? How much will it cost? etc, etc, etc. I don't buy "progress" when none is apparent. Please make it apparent to us. > > > > 73, > > Tony, N2UN > > LM 183 > > Tony and everyone -- > > Forgive me if I'm repeating what you know; I don't have the new issue > of the Journal, I'm just stating what I understand from other sources. > In particular, the AMSAT-UK symposium two weekends ago had a long > presentation on P3E. It is supposed to be done by the end of the year. > Launch costs are prohibitively high, many millions of euros. However, > AMSAT-DL is presenting P3E and P5A as a package to the German national > space agency and hopes it might receive funding in that way. P3E would > be the test-bed for P5A. > > I know you are not asking about this specifically, but I thought at > the time that it did not get sufficient publicity on the bb, so I'm > writing it here. I understand the presentations will be published > online once the video is tidied up. The one on P5A is very > interesting, as is the one on Delfi N3xt. After the presentation on > P5A, I started pricing a dish :-) > > 73, Bruce > VE9QRP

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The Journal and "Progress"
by ANTHONY JAPHA 06 Aug '08

06 Aug '08

Greetings All, Just received the May/June Journal. It is extremely disheartening. For the 2nd issue in a row, there's no status report on Eagle (using the term in the broad sense as W2GPS uses it, to include the possibility of a rideshare). In Rick's Apogee View, there are the most vague references to progress, but the whole piece could have been written long, long ago. No conceivable definition of a progress report would include that writeup. There is not a single specific citation of real progress. We can only assume there has been none. This criticism has nothing to do with the difficulty in identifying an affordable launch opportunity, the discussion of which has been lengthy here. It has to do with getting ready for a launch if and when it appears possible. At one level, this is a chicken and egg problem; without a specific launch opportunity, what is to be built? But, the way to get out of a chicken and egg situation is to acquire either a chicken or an egg. We have neither. Without a chicken there'll never be an egg, and vice versa. Let's get a bird basically ready to go, i.e. designed, prototyped, tested, refined, etc. Where are we on these steps? How much more money is needed to get us there? Is the prospect of raising that amount of money good or is it as grim as being able to afford a launch? I continue to think that there is enough talent here to do the real stuff. That has been demonstrated many times. What there is little evidence of is the capacity to manage the effort in a way that improves the prospects of pulling the pieces (finance, planning, decision making) together. If I am wrong about all this, then please show the evidence. Just where are we on the many pieces that will comprise the bird? When will they be finished? How much will it cost? etc, etc, etc. I don't buy "progress" when none is apparent. Please make it apparent to us. 73, Tony, N2UN LM 183

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Re polarity control box - again
by Angus 06 Aug '08

06 Aug '08

Hi all, its me again, sorry. OK got the 2mtr polarity control box working and very pleased, except for one very small item. LHCP never seemed to me to be 90 degrees out of phase with RHCP, never had the large drop in signal I expected. OK time for a bit or research and looked in to my VHF/UHF manual and found the pages and guess what, the design we have been using is wrong, or so I think, please correct me if I am wrong. OK both yagis have a 1/4 wave 75 ohm matching system to allow the system back to work with 2 x 50 ohm yagis in parallel, in case anyone forgets, so for Vertical both yagis fed in phase, for Horizontal the 135 degrees yagi is fed with a 1/2 wave of 50 ohm line to delay it by 180 degrees, no problems so far. For RHCP the 45 degrees yagi is fed with a 1/4 wavelength of 50 ohm delay line and again no problems. NOW HERE'S THE RUB! For LHCP we feed the 135 degrees yagi with a 1/4 wavelength of 50 ohm line, woops the system has a 1/2 wavelength of 50 ohm line! So instead of feeding as we should we are feeding it to make it simpler than it should be. Hence I was never happy that LHCP was never quite 90 degrees out with RHCP. So quite possibly we are going to get some form of strange oval type of polarity anyone take a guess at its true nature, I may have a play around with one of the antenna programs and see what comes out. Am I wrong completely on this or is it the better to have it off a little on LHCP to get the other 3 polarities correct? Sorry for boring some of you. regards Gus M0IKB

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Th-D7A(G) & HMC-3
by Jeff Yanko 06 Aug '08

06 Aug '08

Hi all, Just wondering if anybody on the BB is using the combination of the TH-D7A(G) and the HMC-3 headset? I have a few questions to ask about this setup. 73, Jeff WB3JFS

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LVB Tracker
by Peter 06 Aug '08

06 Aug '08

Hello, I am trying to setup Rotor Control using SatPC32 and LVB tracker; I am not finding the com port setup location. I would appreciate it if someone could walk me thru the Rotor setup, thank you. 73 Pete, WB2OQQ

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Re: brain picking time
by w7lrd＠comcast.net 06 Aug '08

06 Aug '08

Ed and all Many thanks for the information from many of you. I realize I will need a preamp. For now I will be content to see what I can hear. As you can guess once I can copy signals I will want to join in. That will require at very least mounting the amp at the antenna and a sequencer. I have seen W0LMD' web site as well as several others. I want to start out slow, before I "lose it". 73 Bob W7LRD -- "if this were easy, everyone would be doing it" -------------- Original message -------------- From: Edward Cole <kl7uw(a)acsalaska.net> > Domenico, > > You said it well. I forgot to mention that polarity sense will > reverse upon reflection at the dish surface, so the feed sense should > be Rx=RHCP; Tx=LHCP. In other discussions about using a patch for > eme, concern has been about sidelobe performance and high power > rating of the patch if full QRO eme is considered. Up to 200w it > probably is OK. > > I assumed that Bob was savy enough about microwave weak-signals to > know that on eme a preamp is not a luxury but an absolute > necessity. LMR-400 would be fine for connection from the preamp to > the receiver in the shack, if at least 15-dB net gain is left after > the cable loss is subtracted. More gain is desirable if the receiver > NF is high. A preamp of 0.3 dBNF is standard at 1296 for eme. > > I have a WD5AGO two-stage preamp with 0.30dBNF and 31-dBgain bought > from Radio Astronomy Supply. > > 73 Ed - KL7UW > > At 05:54 PM 8/5/2008, i8cvs wrote: > >----- Original Message ----- > >From: "Edward Cole" > >To: ; "AMSAT-BB" > >Sent: Tuesday, August 05, 2008 8:24 AM > >Subject: [amsat-bb] Re: brain picking time > > > >At 04:35 PM 8/4/2008, w7lrd(a)comcast.net wrote: > > > > >Next question- which probably would be more aimed at a EME bb. I > > >have a 12 foot TVRO I am building a patch feed for 1296, and feed it > > >through 50 feet of LMR400 to my IC-1271A. I want to see if I am > > >able to "hear" EME signals. Of course if I am able to, you can > > >guess what my next effort will be. This will be a cheapie effort as > > >I am only using stuff I already have. I do have a KJ6KO L band 70 watt > >amp. > > >73 Bob W7LRD > > >Seattle > > > > > Bob, > > > > > > Is your patch feed circular polar? EME on 1296 is RHCP in transmit > > > and LHCP in receive. > > > >Hi Ed, KL7UW > > > >It is best to specify to Bob that on 1296 MHz the dish in transmit must > >radiate RHCP in direction of the moon so that the patch or any other > >feed must radiate LCHP in direction of the surface of the dish. > > > > > The switch of polarity sense is due to the fact > > > that reflection at the moon reverses the sense of polarization. > > > >OK > >So that on receiving the wave coming from the moon is received LHCP > >over the surface of the dish but the dish reverse by reflection the signal > >in direction of the feed that must be made RHCP polarized on receiving. > > > >In addition a TVRO dish works well with a patch feed if the F/D ratio of > >the dish is ranging from 0.35 to 0.45 > > > > > might be difficult to achieve with a patch feed. > > > >W0LMD make a patch feed for RHCP and LHCP but never I tested it > > > >Since the target of Bob is to see if he is able to only "hear" EME signals > >at 1296 MHz without to complicate his life I suggest at the very beginning > >to build only a patch feed RHCP polarized. > > > >To receive a 1296 EME signal with a 12 foot TVRO and a IC-1271A > >it is strictly necessary to connect directly to the patch connector a low > >noise preamplifier with a NF in the order of 0.5 dB > > > >Since the gain of a low noise EME preamplifier for 1296 MHz is > >in the order of 30 dB or more then 50 feet of LMR400 connected from > >the output of the preamplifier up to the input of the IC-1271A will not > >deteriorate the overall NF of the system that will be only a little bit > >higher than 0.5 dB > > > > > 73 Ed - KL7UW > > > >73" de > > > >i8CVS Domenico >

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love QRM
by w7lrd＠comcast.net 06 Aug '08

06 Aug '08

Hello What! has Bob lost it? Love QRM! In the context of satellite communications yes QRM can be indicative of a good thing. It tells me this stuff up there is getting used. I can't tell you how many passes of AO7 right up the middle of the US my plaintive CQ calls went unanswered. Looking at the AO-7 Logbook http://www.planetemily.com/ao7/main.php our European friends are using AO-7 like no tomorrow! AO-7 has the largest footprint of all our sats. I suppose this subject makes as much sense as acronyms. 73 Bob W7LRD -- "if this were easy, everyone would be doing it"

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Re: brain picking time
by Edward Cole 06 Aug '08

06 Aug '08

At 04:35 PM 8/4/2008, w7lrd(a)comcast.net wrote: >Next question- which probably would be more aimed at a EME bb. I >have a 12 foot TVRO I am building a patch feed for 1296, and feed it >through 50 feet of LMR400 to my IC-1271A. I want to see if I am >able to "hear" EME signals. Of course if I am able to, you can >guess what my next effort will be. This will be a cheapie effort as >I am only using stuff I already have. I do have a KJ6KO L band 70 watt amp. >73 Bob W7LRD >Seattle Bob, Regarding 1296-eme: The 12-foot dish will do fine on eme and the 70w amp will do fine as a start, especially if you use JT65C. Is your patch feed circular polar? EME on 1296 is RHCP in transmit and LHCP in receive. The switch of polarity sense is due to the fact that reflection at the moon reverses the sense of polarization. This might be difficult to achieve with a patch feed. Many eme stations are going to the septum feed since it produces both senses of circular polarization and eliminates the need for a high power coax relay. See http://www.ok1dfc.com/EME/emeweb.htm for septum designs. 50-feet of LMR-400 will lose a lot of power at 1296 (2.4dB loss); only 42w will reach the dish. You can solve this two ways: upgrade to 1-5/8-inch hardline (61w will reach the dish) or mount the amplifier at the dish (on the back side would work well). Then use a 10-12 foot 1/2-inch hardline to the feed so that 95% of the power reaches the feed. Typical stations on 1296 eme run a minimum of 150w and average 200-300w. I understand from talking with Gordy, WA6ZKY, that a 150w amp is being developed by KJ6KO. I probably let the cat out of the bag so my appology to Greg. 73 Ed - KL7UW

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