Re: [Repeater-Builder] NFCC votes to recommend FCC treat all repeaters as repeaters
At 9/20/2007 03:44 PM, you wrote: Ok, For someone who isnt that much into the rules and regsthat would seem like a duh statement. Why is this such a big deal? To me, a repeater repeats the signal, hince a repeater. Looking at it, I am seeing that you refer to delays and transmission protocolWhat other things out there repeat but arent repeaters? Kenwood SkyCommand. 100s of remote bases in SoCal. I won't speak for other areas, since I'm not familiar with what operators in those areas consider their systems to be. Here, they're auxiliary stations. Don't believe me? Consider that back in the early 70's when repeaters auxiliary stations required separate licenses from the FCC, remote base owners had to submit detailed information to the FCC (block diagrams, etc.) in order to obtain those licenses. Many licenses issued for what most people on this list consider repeaters were actually auxiliary station licenses, which IIRC used callsigns from the standard group D block (2x3) at the time (i.e. WA6BCD); repeaters had the special WR prefix. So if these systems that clearly repeat were repeaters, why did the owners apply for auxiliary station licenses, why did the FCC issue all those auxiliary station licenses to these repeaters after receiving the detailed paperwork clearly indicating the mode of operation? Because these stations, by nature of their operation, were in fact auxiliary stations. Obviously they do repeat, but if they operate within a network of cooperating amateur stations, they can be classified as auxiliary stations. The definition as written is rather loose, but that is a debate for some other reflector. Bob NO6B
Re: [Repeater-Builder] UHF band opening
Does anyone know why the New England bandplan has inverted 70 cm pairs every 25 kHz (unlike the rest of the country, which is either all + or all - 5 MHz)? 25 kHz isn't close enough for any adjacent channel issues to be a concern. Bob NO6B
Re: [Repeater-Builder] UHF band opening
At 9/19/2007 01:52 PM, you wrote: But, what would you realign it to? I believe PAVE PAWS covers the entire band. There is no spectrum left to put them. Perhaps they can be QSY'd during the QRT period, assuming PAVE PAWS will only operate for a few years given that one site has already been shut down. When I was in Cape Cod last month there were still some 70 cm repeaters operating, but the locals were talking about a total shutdown. Don't know if it's happened yet. Maybe they can move up to 450-451 as long as they don't cause interference to users there... (a dig on the D-STAR repeaters operating in non-repeater bands due to 'no repeater band spectrum left and non-interference where they are operating'). ;- What amateur modes are legal outside the amateur bands? Bob NO6B
RE: [Repeater-Builder] Digest Number 5793
At 9/18/2007 12:52 PM, you wrote: Thanks to all for the input to my question. The background: Over the air monitoring with a service monitor yielded 13 to 15 KHz deviation from the three digis in this area on high to medium mountain sites. My problem is a 50 dB sig from the digis into a FM voice repeater receiver on a near by site (within 300 feet). If the digi that's bothering your input RX is only 300 ft. away, modulation sidebands may not be the only problem. Also, what is a 50 dB signal? 50 dB above the noise floor? -50 dBm? How many kHz away from your input is the (center of the) interfering signal? Bob NO6B
Re: [Repeater-Builder] Re: 220 link radios
At 9/13/2007 04:10 PM, you wrote: QST wrote a 224 MHz radio review a few years back and I had been meaning to save it. Three or four of the available 224 MHz radios were covered. Alinco, ADI, Kenwood, Icom and someone else... at least. Alinco Radios have a pretty good reputation and my ham friend likes to beat the snot out of his gear... yet it keeps on playing like the day it was built. Of the two Alinco Radios that I know were returned for service... both were fixed right the first time and returned in a semi normal amount of time. The older Alinco radios have a good reputation. The currently production models are essentially junk. I bought a brand new DR-435T a couple of years ago ended up returning it because the front end RF amp in all DR-435Ts oscillates. So you don't believe me? Try this: unplug the antenna, open the squelch start tuning across the 440-450 MHz band. I guarantee you'll find a 30-40 kHz segment where the S-meter indicates a significant noise signal - probably full scale on the S-meter. Now put your hand against the side (I don't remember which side) and/or just underneath the radio. What'dya know, the noise went away! Not really, it just moved another 30 to 60 kHz away. Go ahead plug the antenna back in; it'll still oscillate. The noise is strong enough to take out otherwise full quieting signals. The radio I exchanged with the repair center had the same problem, only at a different frequency. The frequency of oscillation also varies greatly with temperature, so when the radio was at just the right temperature it stopped receiving the local repeater. I also tried the above test on the DR-435T on display at Dayton this year, thinking surely they must have fixed the problem by now. No!!! I don't know if the 2 meter or 220 MHz versions have this problem. Probably not, but I'll bet the CTCSS decoder takes anywhere from 1 to 3 seconds to decay. Not acceptable behavior for a CTCSS'd link IMO. My all-time favorite for 220 repeating linking is the venerable Midland 13-509. No IMD, no failures of any kind. Period. Recently I've found the ARRL product reviews to be lacking in meaningful content. The authors seem to be a lot more interested in audio quality bells whistles rather than actual performance. The 2-tone 3rd order IMD numbers they publish often vary greatly from what I measure, which of course seem far more reasonable (example: for the Alinco DJ-G5T ARRL labs claims a 2-tone dynamic range of 90 dB @ 10 MHz tone spacing! Now the G5 is a great radio - I own 2 of them - but 90 dB SPDR just isn't happening with this radio). Bob NO6B
Re: [Repeater-Builder] Re: 220 link radios
At 9/13/2007 10:16 PM, you wrote: Don't know if I have a Service Manual for the 3530, but I probably have a copy of the diagram. I'm moving my shop files around this weekend and after things settle down I'll look to see what I have for the 3530 and scan it into pdf for everyone (free copies). You guys need to buy a can of Caig Labs DeOxit and/or ProGold G5 Spray and try it on your crunchy pots. It's the only product that I've found actually works if there's any chance of reconditioning the pot operation. Ahh, yes, the Caig stuff. My all-time favorite is actually R5 (later called Power Booster). Unfortunately I think they've discontinued it again, so DeOxit ProGold are your best bets. I think the only difference is the ratio of cleaner to protectant. Trust me on this one... it's some of the best money you can spend on a spray (get the spray can) contact restoration compound (liquid). Ditto here, absolutely! Bob NO6B
Re: [Repeater-Builder] D-Star systems as auxiliary stations?
At 9/7/2007 06:34 AM, you wrote: Bob Dengler wrote: Someone should tell Kenwood, as their SkyCommand system clearly repeats onto 2 meter frequencies. But it functions as a 'remotely controlled base station', not a repeater, the way I understand it's operation. Yes (although that term is not defined in the rules). It repeats as part of its overall function. It's not repeating from one 2M freq to another that I know of. It certainly would not be an easy thing to do. Correct. Now, if it was able to be set up so that the primary control was on a 2M freq-ANY freq, that would not be legal. Control needs to be 222.xxx and above. No, that was changed. E-mail me privately if you'd like more details. Bob NO6B
Re: [Repeater-Builder] D-Star systems as auxiliary stations?
At 9/5/2007 06:44 PM, you wrote: True, but if either capacity is not legal on the frequency, it cannot be used as both at the same time. Joe M. I disagree, as the rules do not explicitly state this. This would also make Kenwood SkyCommand illegal to use in the 145.5-145.8 band segment, which I do not believe was Kenwood's intent. If this continues to be a point of contention, perhaps Kenwood can be persuaded to file another request for rulemaking to explicitly add 145.5-145.8 to the repeater subband. That would put an end to the debate. Bob NO6B
Re: [Repeater-Builder] D-Star systems as auxiliary stations?
At 9/5/2007 08:42 PM, you wrote: There's no reason why a particular piece of equipment can't be used in both capacities at the same time. Consider a 440 repeater, with an attached 2m remote base (remotely-controlled station). The UHF repeater receiver operates as both the repeater receiver and the auxiliary control link receiver for the remotely-controlled station concurrently. But if it's a repeater AT ALL, it is PROHIBITED in the 145.5 - 145.8 sub-band! Someone should tell Kenwood, as their SkyCommand system clearly repeats onto 2 meter frequencies. Auxiliary operation is allowed on 145.5-145.8 MHz, incidental repeating notwithstanding. Bob NO6B
Re: [Repeater-Builder] D-Star systems as auxiliary stations?
At 9/6/2007 11:46 AM, you wrote: The relevant repeater rule is 97.205(b): --- (b) A repeater may receive and retransmit only on the 10 m and shorter wavelength frequency bands except the 28.0-29.5 MHz, 50.0-51.0 MHz, 144.0-144.5 MHz, 145.5-146.0 MHz, 222.00-222.15 MHz, 431.0-433.0 MHz and 435.0-438.0 MHz segments. Therefore, if a station is used as a repeater (in addition to ANYTHING else or by itself) it cannot operate between 145.5-146.0 MHz among other places. It's an exclusionary rule (where it cannot operate). If it existed in the rules by itself, yes. The fact is you also have 97.201(b), which permits auxiliary operation in the 145.5-145.8 segment. SkyCommand is Auxiliary operation (and only that as confirmed by the FCC), ...but it repeats (automatically retransmits) communications onto 2 meters, as you've clearly indicated. How could it not also be a repeater? I see no point in continuing this thread. We just agree to disagree. Bob NO6B
Re: [Repeater-Builder] D-Star systems as auxiliary stations?
At 9/6/2007 01:07 PM, you wrote: Bob Dengler wrote: At 9/6/2007 11:46 AM, you wrote: The relevant repeater rule is 97.205(b): --- (b) A repeater may receive and retransmit only on the 10 m and shorter wavelength frequency bands except the 28.0-29.5 MHz, 50.0-51.0 MHz, 144.0-144.5 MHz, 145.5-146.0 MHz, 222.00-222.15 MHz, 431.0-433.0 MHz and 435.0-438.0 MHz segments. Therefore, if a station is used as a repeater (in addition to ANYTHING else or by itself) it cannot operate between 145.5-146.0 MHz among other places. It's an exclusionary rule (where it cannot operate). If it existed in the rules by itself, yes. The fact is you also have 97.201(b), which permits auxiliary operation in the 145.5-145.8 segment. Interesting that you deleted the quoted text where I mentioned 97.201(b). The point is that if it is a repeater - by itself or in addition to any other operation - it is prohibited there. The fact that it may be AUX operation IN ADDITION to that does not mean you can ignore 97.205(b). ... this is where we agree to disagree. If you want to continue this Joe, please move it off the reflector. I'd imagine Kevin's probably had enough of this already. Bob NO6B
Re: [Repeater-Builder] D-Star systems as auxiliary stations?
At 9/5/2007 12:45 PM, you wrote: 4. It does NOT carry out point-to-point communications over amateur frequencies, but rather, over a LAN, WAN, or the internet. Not true; it uses a combination of both. If there were no TX or RX involved, then yes it would be only using internet no license would be required. On the RF side, it is STRICTLY user-access. I maintain that it therefore does NOT meet the definition of an auxiliary station. Our local OOs do not share your conclusion. 5. According to one of the postings on Icom's D-Star forums, the developer(s) of D-Star have ALWAYS envisioned and called it a repeater system, as does the current sole vendor, Icom. Yes it may be a repeater, but it's also an auxiliary station. Bob NO6B
Re: [Repeater-Builder] Re: subaudibe tones..
At 9/5/2007 04:11 PM, you wrote: And Here is a Dumb Tech Question , If You had a PL And had the receiver SQ All the open would Not the Receive Be hotter then with No Pl and the SQ Closed enough to keep from keying up / The answer is, no. I wouldn't say no for all examples. Depends on the squelch circuit, how it operates (designed) and where it's set. Also depends on the ctcss decoder circuit type and how it operates. Pitting the most sensitive CTCSS decoder vs. the most sensitive noise squelch, I'd have to give the edge to the CTCSS decoder provided the user runs at least 700 Hz of CTCSS deviation. Personally I still use Micor squelches on my CTCSS'd inputs, but they serve only as poor man's STE. Bob NO6B
Re: [Repeater-Builder] Ramsey COM3010 Service Monitor Opinions
At 9/3/2007 11:31 PM, you wrote: On Sep 1, 2007, at 4:19 PM, Eric Lemmon wrote: Maybe I'm just a crab, but I wonder if you'd be better off buying a good used IFR or H-P service monitor that has more features, for about the same price. Keep in mind that a new service monitor with a few very useful options- the R2600D comes to mind- is in the $15,000 class. You get what you pay for! But, hey, if you have only the basic needs for measurement of power, center frequency, and audio deviation, maybe the Ramsey unit is ideal. Choose wisely. Eric's not a crab, he's right... It took me three years of searching and asking every single person I knew, but I eventually found an IFR 1500 for $2000 from a private seller who even performed a repair on it when he pulled it out of storage and found that it had a video sync problem. There were lots of IFR 1200s at Dayton this year; the market prices should be dropping as more analog-only test equipment hits the surplus market. Bob NO6B
Re: [Repeater-Builder] [Fwd: DStar Channel Spacing]
At 9/2/2007 10:21 AM, you wrote: Bob, Does this mean TASMA has made the determination that DStar repeaters are not by definition a repeater (as part 97 would define a typical analog mode repeater) and can be operated outside the defined repeater sub bands as an auxiliary station while still performing the functional equivalent of an analog mode repeater? Ed Yoho WA6RQD We do not address the issue of whether D-Star systems are repeaters. We do claim that they fit the definition of an auxiliary station as defined in Part 97.3 (a)(7) therefore may be operated in the 145.50-145.80 MHz segment. Bob NO6B Interesting. Does TASMA consider other digital format (P25, etc.) systems to also be within the auxiliary class? It would probably depend a bit more on the specific usage, since P25 AFAIK doesn't have the routing features of D-Star that make it a system of cooperating amateur stations. Also I believe P25 requires 12.5 kHz channel spacing, so it's currently too wide to fit within our 10 kHz channels. Bob NO6B
Re: [Repeater-Builder] [Fwd: DStar Channel Spacing]
At 9/3/2007 11:58 PM, you wrote: For better or for worse, the Report Order that went through this year with the CW changes, etc... also included allowing Auxiliary stations in 2m. (Note: Many areas local bandplans have not kept up, and may never... VHF is busy and cramming in more Auxiliary Stations is retarded when there is plenty of spectrum in 220, UHF and on up. I argued, bellowed, and generally made an ass of myself for years about simplex IRLP nodes (since I'm one of the IRLP server and installation volunteers, I felt I should say something, once in a while anyway), on 2m simplex which were completely illegal unless someone was physically present at the IRLP node and acting as a control operator... this also applied to EchoLink and others... up until this rule change took affect. FWIW, the control op didn't need to be physically at the IRLP node in order to control it, but rather present at a CONTROL POINT. This means one could control their IRLP node via a radio control link (not common but possible), or (more likely) via the internet from another location. I don't know about Echolink, but for IRLP I can control our club's node from any place I can run an SSH client. Bob NO6B
Re: [Repeater-Builder] Re: subaudibe tones..
At 9/4/2007 12:40 PM, you wrote: Al, Has nothing to do with pride, just sound sense that we don't need tone. Tone has its uses, but not a solve all problems approach. In my case solves no problem and in fact does create one...vacationers have trouble finding the tone freq. Most directories are not always up to date and to have a computer on vacation to look it up is not what many can or want to do. True, but if a particular area standardizes on one CTCSS tone frequency, the directory becomes insignificant as the repeaters once again become just as easy to find as carrier-access systems - just without all the open squelch blowing from the distant weak signals on the input from that band opening. Bob NO6B
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
At 8/30/2007 08:00 PM, you wrote: Isn't LDF a copper shield with an aluminum core that has copper coating on it? Jesse Yes. I was referring to the shield material. Bob NO6B On 8/30/07, Bob Dengler mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote: Under my previous site manager, aluminum hardline was banned from the site. Bob NO6B
RE: [Repeater-Builder] Duplexers
At 8/29/2007 06:40 PM, you wrote: If you have two watt meters and an antenna matching device you can put one wattmeter between the transmitter and the matching device and tune it for minimum reflected power on the first meter. Then with a second meter between the tuner and the mismatched load you can see the second wattmeter that is reading the reflected power. The second wattmeter will have a higher forward power reading than the first due to the added re-reflected power. This doesn't sound right either, as there should be no reflected power at the antenna if it's been matched further down the line. The tuner would be adjusted so as to create a conjugate impedance of the antenna at the end of the feeding coax, thus eliminating the mismatch. My guess is that the higher power reading on the wattmeter is due to the weird impedances it's seeing on both its input output. Bob NO6B Hi Bob, Please read again what I wrote. I am not sure that you are following how the meters are in the circuit. Remember that whatever you do at the transmitter end of a transmission line has no affect on what is going on in the line itself. The only thing that will change the swr on the line is what you do at the load. 73 Gary K4FMX OK, after talking to a senior RF engineer at lunch here at work I think I understand what's going on. The part that threw me was having the matching circuit in the middle of the feedline the fact that any reflected power from the load MUST be totally re-reflected back by the matching circuit, otherwise there would be power reflected back to the TX, which by definition does not occur in this example. Because of the multiple re-reflections between the matching circuit load resulting in multiple waves back forth within that coax section, typical single-wave thinking doesn't apply. I guess it's a useful way to illustrate why coax gets lossier if you use a tuner far from the antenna. Bob NO6B
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
At 8/30/2007 03:45 PM, you wrote: The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX� product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as direct replacements. Under my previous site manager, aluminum hardline was banned from the site. Bob NO6B
Re: [Repeater-Builder] Re: subaudible tones..
At 8/28/2007 09:26 AM, you wrote: Still, you can't build an effective LPF for it. Best you could do would be to put a 6 dB/octave LPF that broke around 2 x 67 Hz, let the higher tone frequencies get rolled off. Either way, you still get buz... Do you assume multiple frequency operation? Yes. I set the oscillator to one frequency and park it inside the radio. Place the sonic page described or similar rc filter in line and try the circuit. You'll find it works pretty well for what it is... the only buz that makes it to and through most modulators is pretty much only the desired ctcss frequency. I've never experienced a case where the delivered audio was objectionable. Well, I did in every case. Not surprising, as there's a lot of odd harmonic content within a square wave; I suppose the lack of a 2nd harmonic helps your LPF design a little. Plus if you're feeding a phase modulator, you've got another 6 dB/octave working against you. Perhaps you were feeding direct FM modulators using higher CTCSS freqs.? Perhaps it's a difference of perception. Back in the day, there was a rather high emphasis (pun quasi-intended) on PL tone purity. If your encoder had any harmonic content others let you know. In addition, some of the repeaters around here seemed to 'emphasize' the PL harmonics for some reason, as they sounded worse through the repeater than when heard directly. I never found the 555 to be very stable; the XR2206 always did better. Bob NO6B But the 2206 tends to be much less tolerant of voltage and temp changes as found in 99% plus mobile radio operations. Otherwise a great chip for what it is... From the respective data sheets: drift w/temperature (typical): LM555: 150 PPM/°C XR2206: 20 PPM/°C drift w/supply LM555: 0.3%/V XR2206: 0.01%/V Looking at the drift specs, it looks like all my drift problems with the XR2206 were likely limited to the Rs Cs used, as even a 50 °C change would only result in a typical 0.1 Hz drift @ 100.0 Hz (due only to the chip). Bob NO6B
Re: [Repeater-Builder] Re: subaudibe tones..
At 8/28/2007 12:39 PM, you wrote: If CTCSS is still turning people away after almost 40 years of it being out there and in heavy use for at least 30 years, perhaps they need to be. In rural and remote areas it often ends up a bit of chore for traveling-through mobiles to locate the proper rx ctcss. Unless an area visitor already knows about the available repeater most open machines are easily missed. One concept that really helps in this area is CTCSS tone frequency standardization, IOW tones by region. All you then need to know is the freq. being used in the area you're traveling to. Many areas are already well established: 110.9 in Rochester NY, 107.2 in Niagara Falls San Diego, 131.8 in Santa Barbara, 127.3 in Springfield MA. Even if you don't know what tone is in use, all you have to do is find the tone of one system. After that you can find the others by kerchunking (with ID of course!) all the other pairs with that tone. Bob NO6B
Re: [Repeater-Builder] Re: subaudibe tones..
At 8/27/2007 03:56 PM, you wrote: Yep. That's what I did, added a ComSpec encoder to my 4AT. My Tempo S1 has the added encode with DIP switch. Both radios work fine today. Chuck WB2EDV Yeah, I had one of those for each band (S5, S2, S4). The problem with the S2 original S1 (not S1A) was keeping the TX from going spurious after adding the encoder (due to RF coupling in out of the encoder wires). Bob NO6B
Re: [Repeater-Builder] non-silver RG-214 was Lloyd is Well was Cable Lengths
At 7/27/2007 03:17 PM, you wrote: After just getting through turning a set of Aerial Facilities Limited SC-220-2N Band Pass cans into a Band Pass Band Reject (tm) duplexer here is what I am going to share from my experiences. The Science Behind It: Please refere to US Patent #4080601 My Experiences: Please refere to: http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=252104937http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=252104937 http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=286228333 http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=289106710http://blog.myspace.com/index.cfm?fuseaction=blog.viewfriendID=85474861blogID=289106710 Be careful about using non-silver-plated coax in a duplex line, even if it is double-shielded. I've had that stuff cause intermittent desense after being in service for a couple of years, it was indoors. Bob NO6B
Re: [Repeater-Builder] non-silver RG-214 was Lloyd is Well was Cable Lengths
At 7/30/2007 02:21 PM, you wrote: Bob That doesn't square with the large body of repeater owners who have used Wacom cavities. Their UHF products used RG-142. However, their VHF products used a proprietary cable which had: MODIFIED RG-214 DOUBLE SHIELDED which was nothing more or less than RG-214 without silver plating. Despite anecdotal experiences like yours, I've never heard a complaint from anyone who used that Wacom modified cable regarding desense. Have you? I can't speak w.r.t. the interconnecting cables on a duplexer. However, any braided cable that carries full duplex signals where there is a ratio of over 170 dB between the TX RX signal levels needs to be silver plated, or sooner or later it generates IMD that results in (among other things) TX noise being intermittently mixed with the TX carrier onto the RX frequency. Perhaps the actual TX to RX signal ratios within the duplexer cable harness are less, which would explain why copper-braided coax works OK there. I just wouldn't use it anywhere between the antenna duplexer. Bob NO6B
Re: [Repeater-Builder] Re: Coax length between added cavity and duplexer
At 7/26/2007 10:54 AM, you wrote: Skipp said: I don't have time to debate or argue the point... but I will write that I don't agree with the above statement. We can go back and forth about that later on if you like... cruising7388 said: Yes, indeed it is a critical length if if is your desire to superimpose the bandpass curve properly on the pass curve of the duplexer. It should be an electrical 1/4 wave that accounts for the velocity propagation of the cable plus the electrical length of the coupling element in the Celwave cavity ---I suspect Skipp is referring to the same issue BUTNate specifically said he had an extra Celwave BANDPASS cavity. Yes I know that if we were dealing with a Bp/Br cavity, coax length between it and other Bp/Br cavities IS a factor. But I stand by my comments that all things being equal - coax length absolutely does NOT matter if the impedances at each end match the coax's characteristic impedance (ie 50 ohms is maintained). 1/4 wave, odd multiples thereof, 1/2, etc would make absolutely no difference whatsoever is impedance's matched throughout 50 ohms is ONLY at the pass frequency. The concern here is that the wrong cable length between the pass cavity duplexer can cause undesired effects at reject frequencies. Specifically, for maximum off-frequency rejection the electrical distance between the pass can duplexer needs to be a 1/4 or 3/4 wavelength. You can use any other length you wish but then the off-frequency rejection characteristics of the pass cavity may suffer. Bob NO6B
Re: [Repeater-Builder] Re: Horizontal Polarity Repeater Antenna
At 7/24/2007 05:27 PM, you wrote: --- In Repeater-Builder@yahoogroups.com, skipp025 [EMAIL PROTECTED] wrote: Re: Horizontal Polarity Repeater Antenna Got to love a horizontal repeater antenna array. Maybe being down under has something to do with it?? Too right! Bob NO6B
Re: [Repeater-Builder] ctcss and dcs at same time?
At 7/2/2007 12:22 PM, you wrote: I think that either way, it's up to the individual receiver as to how well it operates, if at all. I'd suggest that you don't do it rather than risk some radios working and some not. You could run two CTCSS tones, but beware of the sum and difference frequencies. If the difference happens to be near another CTCSS tone frequency, you'll get falsing on that frequency as well. Also, the sum will Wouldn't that require mixing (distortion)? FWIW, I once tried using 2 CTCSS tones on one of my links (all G.E. MVP TX RX). If they were 1 or 2 standard tone frequencies apart, the G.E. CG decoders wouldn't decode either of them. However, if they were 4 or more standard freqs. apart, it seemed to work. Bob NO6B
Re: [Repeater-Builder] Are there any advantages to DCS ?
At 7/2/2007 02:16 PM, you wrote: DCS is a lot less prone to falsing than CTCSS is. In particular, two paging system transmitters could cause a heterodyne that's 100 Hz apart. This will very nicely pass right into a CTCSS decoder and key a repeater or even open the squelch of a receiver. DCS just doesn't react to constant tone modulation. I've never seen a heterodyne open a CTCSS decoder, but I guess it's theoretically possible. Something else to consider is that the implementation of CTCSS decoders in many current-production ham equipment is lacking. In particular they are prone to falsing on plain ol' white noise (the Kenwood G707 V7A mobiles were notorious for this), slow release times. I suspect DCS by its nature wouldn't have a noise falsing problem, the slow release time is negated by the turn-off tone. Bob NO6B
Re: [Repeater-Builder] ctcss and dcs at same time?
At 7/2/2007 04:31 PM, you wrote: In your case, it sounds like you're trying to link to IRLP, perhaps? It's probably better to just switch the whole repeater to CTCSS-follows-user when IRLP is active, and back the other way if you want when not. We're doing this on one local system: the node sends DTMF to the repeater (like yours) to put it into tone on COS mode, but it also sends another string to put it back into tone always mode when disconnecting. I guess the users like to hear the reset beep while decoding. It's worked quite well over the years. Bob NO6B
Re: [Repeater-Builder] First repeater?
At 6/27/2007 12:53 PM, you wrote: Yep. I didn't see what that rule change happened, but I know it did. I also know that there was an FCC-issued moratorium on new repeaters in 1985, but I never found and don't recall how long that lasted. I think I never heard of any such moraturium, around that time I was placing several new systems on the air. Bob NO6B
Re: [Repeater-Builder] First repeater?
At 6/25/2007 08:00 PM, you wrote: At 07:56 PM 6/25/2007, you wrote: What country are you in? The first amateur repeater in Canada was VE3RPT in 1965, which is still on the air but now in its forth (soon to be fifth) incarnation. ---Sorry but no :-) http://www2.arrl.org/qst/2004/03/pasterna.pdf Not the first, but one of the 1st (maybe 2nd?) certainly the most complex of its time: http://wa6tdd.tripod.com/ Between the audio processing circular polarized antenna, it was perfectly copyable all over the LA basin on an old deaf multiband (AM/FM/shortwave/VHF) receiver. Remember these things only had a wideband FM receiver. Bob NO6B
RE: [Repeater-Builder] DCS decoder software?
At 5/31/2007 03:04 PM, you wrote: AIE (automated Industrial electronics) used to make a pl/dpl counter box. It would count all tones and the number of hits on each. There may be some floating around yet. I may even have one stuffed in the closet yet, not sure. Speaking of AIE, they also used to make a service monitor (FM-110). If anyone has any manuals or schematics on this thing I'd appreciate hearing from you. AIE is still in business but has no data on it. Bob NO6B
Re: [Repeater-Builder] Re: Combined/Coupled Repeaters/Transmitters
At 5/30/2007 09:26 AM, you wrote: The power loss through the two tx legs would be interesting. Something on the order of 3 or 4 dB maybe? More like in the low 2's. Definitely under 3 dB. Same antenna? multiple or split antenna? Just 1 antenna for everything. This is a residential site with nothing else around, so the filtering requirements were not as stringent. We just had to keep the TXs out of each other the RXs. 1 standard notch duplexer, 1 wide-split miniplexer, a couple of pass cavities isolators a crossband diplexer got 'er done. Bob NO6B
Re: [Repeater-Builder] Re: D-Star demo
At 5/30/2007 01:10 AM, you wrote: While the typical 50 dB analog NBFM (5 kHz deviation) bandwidth is ~20 kHz, the 50 dB bandwidth of DStar appears to be about 10 kHz. Here in SoCal we're proposing 10 kHz channel spacing for DStar, digital P25 any other very narrow band digital voice, or VNBDV, systems. Discussion here locally is leaning toward 12.5 KHz spacing for what's really needed for P25 Phase I systems, not 10 KHz. The discussion was also backed up with tests of real-world BER (bit-error rate) at closer and closer spacings (overlapping) by a local Amateur with access to the appropriate P25 test equipment. In lab testing, 10 KHz spacing and it's effect on P25 BER is not real pretty. Sounds like DStar MAY have an edge over P25 Phase I, at least in terms of occupied bandwidth. (Good luck finding test equipment that supports D-Star. Ever.) I guess you weren't at Dayton. Bob NO6B
RE: [Repeater-Builder] Re: D-Star demo
At 5/30/2007 07:08 AM, you wrote: No they don't however, Icom recently teamed up with Kenwood to develop and deploy another new digital mode (as yet unnamed last I heard) that reportedly operates within the new FCC ultra narrow 6.25Khz channel plan. An Icom America representative recently told me that this new digital mode in their commercial line (see the F5061 and F6061) is very similar to D-Star but not interchangable with it. Gary This may be the basis for the rumor at Dayton that Kenwood demoed a DStar radio in Japan. Don't see anything about it on the Kenwood Japan web page, though. Bob NO6B
Re: [Repeater-Builder] Combined/Coupled Repeaters/Transmitters
At 5/29/2007 04:56 PM, you wrote: If you have worked with multicoupled recieve antennas and combined transmit antennas, or a community antenna-type site, please drop me a line off list. I have a few questions regarding your experiences with implementation versus theory. My last system had: 445 MHz TX 422 MHz TX 439 MHz RX 440 MHz RX 2 meter repeater all running simultaneously on one antenna. What would you like to know? Bob NO6B
RE: [Repeater-Builder] Re: Quasi-Simulcast?
At 5/11/2007 09:45 AM, you wrote: There's good reason a hot air alarm probably went off for many of you when reading the article. I'm trying to figure out what his closing paragraph is trying to say: A duplexer is working correctly when the sensitivity of the receiver is not degraded when the transmitter becomes active. There are test procedures to check this out, but the explanation of these tests is beyond the scope of this article. [OK, I'll agree with him so far] However, should you hear a slow oscillation of the transmitter when it turns on and off (a rate of about 1-2 Hz rate on weak signals), then you do have duplexer desensitization. What is this 1-2 Hz oscillation he's talking about? In the context of the above, he's probably referring to the repeater transmitter cycling on off due to loss of input signal when the TX is on due to desense. His hang time is probably only 1/2 second, hence the 1-2 Hz TX cycling period. BTW, I quasi-simulcast 2 UHF TXs about 70 miles apart; one is 1000 ft. AMSL the other is 7000 ft. Some low hills between them but not much dirt otherwise. Only TX stabilization is temperature-controlled xtals on both. I try to keep them within 50 Hz but one xtal is aging a bit so right now they're about 200 Hz apart. Still, the heterodyne in the overlap areas is not bad the system is perfectly usable everywhere. Only thing missing is the 2-channel voter. I have the hardware to put it together but there isn't enough usage of the system to justify the time spent to do it, so for now the 2 RXs are selected by CTCSS freq. Bob NO6B
Re: [Repeater-Builder] Re: [Fwd: [SCOM-Controllers] 7330 pricing and other news]
At 5/11/2007 03:22 PM, you wrote: For those manufacturers who don't plan to be at Dayton, will they be sending a demo unit and brochures to show off at someone's inside booth or outside swap meet space? LinkComm will be there, according to their web page. Haven't heard from Ken. Now is that a new RC-210 or the previously hinted RC-8xx expandable to 8-ports controller? Bob NO6B
Re: [Repeater-Builder] Re: 3 minute timeout. FCC regulation or myth
At 5/3/2007 09:46 PM, you wrote: On 5/3/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: BTW, the 3 minute control link failure or heartbeat timer rule is still in Part 97 (97.213b). This is the most ignored rule in Part 97, as virtually no one implements such a control link. The way I read it, only a Telecommand Station needs the 3 minute timer on something called a control link. I figured someone would get tripped up on the confusion between telecommand telecommand station after I sent my last message. Yes, a telecommand station only controls a space station. However, look just above telecommand station in the definitions section (97.3): telecommand simply refers to controlling a device at a distance. So your repeater station may be remotely controlled by telecommand without using a telecommand station. 97.213 then spells out specifically for non-space stations (less than 50 km altitude) under what conditions telecommand may be used to control same. So yes if you use remote control, that is telecommand in theory the 3 minute heartbeat timer is required. However, nobody does this so the rule will probably continue to be ignored until someone puts in a Request for Rulemaking that deletes it, which I'm sure would sail through the rulemaking process. Bob NO6B
Re: [Repeater-Builder] quick question about spectrum analyzer noise floor
At 4/24/2007 09:50 AM, you wrote: Could anybody clarify how one does lower the noise floor of the analyzer? It was my understanding that the noise floor is a intrinsic characteristic of the instrument itself, and is so to say a measurement limit that cannot be varied without external aids (or maybe with a low-noise LNA?). But if one uses an external amplifier, wouldn't this also raise the site noise floor on the analyzer screen? Not if the SA is self-noise-limited. For example, for a 10 kHz resolution bandwidth, the noise floor of a typical environment @ UHF is going to be somewhere around k*290*1, or ~134 dBm. If your spectrum analyzer's noise floor at that resolution BW is -110 dBm, then you need at least 24 dB of gain ahead of its input to see down to that level. Fortunately, you don't need weak-signal DXer-grade sensitivity, so the 16 dB or so you get from an Angle Linear PHEMT LNA should be sufficient. Just subtract the gain of the added LNA from the display reading you've got your amplitude. As others have pointed out, you can also reduce your resolution bandwidth, but once you reduce it to less than the bandwidth of the signals you're looking for (10 kHz for NBFM, already pushing the limit a bit), the signals of interest are reduced as well as the noise. You'll still see unmodulated or weakly modulated carriers at resolution BWs down to Hz, but when modulated they may disappear into the noise. Or if I am wrong, how could one lower the noise floor of the measurement in order to be able to take measurements at lower levels? Or is the noise floor also a function of the SITE noise level per se? I'm familiar with quite a few comm. sites in SoCal know of only one that seems to have a minor broadband noise problem @ UHF. If there's a lot of RF at the site you're investigating, you might need a 2 MHz window filter in front of the LNA. A cavity filter with low-loss loops may also just cover the 2 MHz span you need, though there will be a little attenuation at the edges. Bob NO6B
RE: [Repeater-Builder] quick question about spectrum analyzer noise floor
At 4/24/2007 11:31 AM, you wrote: Can Someone Please put the Spectrum Analyzer thread in Layman Terms I have a Motorola Serv Monitor R2001C With the Analyzer and a Icom R-7000 Communications Receiver with a AVCOM Spectrum Analyzer I Can see 10 Mhz at a Time and I know that it's nice to Find Signals. But I always thought that a Actual receiver IE Scanner running the right Software would actually find and see more Hits because it is actually a Receiver. I know for a fact I can hear a lot more on a Cheap Scanner then using a Service Monitor on the same antenna. What do I not understand here A spectrum analyzer is a very fancy, amplitude-reading scanner. Some like the IFR A7550 have detector options so by setting the span to zero one can actually use it as a receiver. Spectrum analyzers typically have more dynamic range bandwidth than a scanner, that dynamic range bandwidth comes at the expense of sensitivity. Some quality SAs I've used have noise figures in excess of 30 dB. If you want to see more on your SA, put a preamp in front of it. Bob NO6B
Re: [Repeater-Builder] Repeating D-Star
At 4/24/2007 05:17 PM, you wrote: I don't know. Like any other radio gear it depends on the brand, model, and how badly the seller wants to sell I guess. Motorola isn't the only maker offering P25 digital audio capable radios (we'll assume CAI/IMBE compatible). Icom, Kenwood, and others are also offering rigs and surplus stuff pops up at the most unexpected times. Gary What would be far more interesting to me would be for one of the ham manufacturers to offer a P25 user radio. How much would adding the vocoder add to the cost of a current analog FM model? If it's comparable in price to Icom's DStar radios (which are substantially more than their analog counterparts - roughly double the cost), it just might be worth it. Something to add to my wish list of radio features to deliver to the reps. at Dayton, along with better IMD performance split CTCSS tone. Bob NO6B
Re: [Repeater-Builder] New file uploaded to Repeater-Builder
At 4/16/2007 10:00 PM, you wrote: Good thinking Bob, I will look in to it. Do you have a schematic or the model number of the squelch you were working with? No schematic handy here. It was the stock squelch circuit in a mid-80's vintage Hamtronics R144 or whatever repeater grade RX they were selling at the time. The noise filter was a simple 2-pole BPF with a very high Q. The op amp they used was the dedicated op amp within the MC3357 or MC3359 IF amp/detector-on-a-chip. Nothing wrong with the op amp, just the circuit design around it. I would think ringing would be a problem with passive components Like L/C filters. But it may exist in a low quality op-amp that is not designed with a wide bandwidth. In this case the op amp isn't the problem, it's the overall circuit. I believe the LM324 series is only rated for 12kHz of bandwidth, the TL084 is about 3MHz. The unity gain BW of the LM324 is 1 MHz; the TL084 is 3 MHz. I wouldn't use either one much above audio frequencies. I am not even sure if I can simulate impulse noise. But in theory we can write a software algorithim to look for a patterned pulse and attempt to compenstate. Any decent SPICE simulator should be able to give you the transient response of your filter. Bob NO6B
Re: [Repeater-Builder] Rethinking the Possible poll question
At 4/16/2007 10:21 AM, you wrote: Bob Linda Smith wrote: Dear Chuck and everyone else who gave valuable suggestions, It looks like I, and the club, need to rethink this question. I am very impressed with some of the new equipment out there and was thinking our radio is a bit outdated. Also, I was thinking of the space we occupy in our shared building. Thinking a smaller foot print could be hung on the wall easily. Unless you're being told to shrink your footprint in the building, I wouldn't voluntarily do it. Now, making the package smaller so you can fit in other stuff, well, that's different ;c} Not much different: G.E. MVP. I once walked a hamfest with a complete operating in-band 2 meter MVP repeater in my backpack. Bob NO6B
Re: [Repeater-Builder] Rethinking the Possible poll question
At 4/16/2007 11:45 AM, you wrote: Who/how many people carried the Duplexer? It was in the backpack. This was a wide-split (2.5 MHz) system, so the duplexer was actually the lightest component. The MVP 11 AH battery were a bit heavy to carry around, but they were manageable. Bob NO6B
Re: [Repeater-Builder] Re: Rethinking the Possible poll question
At 4/16/2007 03:44 PM, you wrote: : G.E. MVP. I once walked a hamfest with a complete operating in-band 2 meter MVP repeater in my backpack. You the guy with the plastic helmet with the rubber duckie on top..? or are you the guy with the entire tower top mounted beam (yagi)? Neither. I just used a mag mount stuck out the back of the backpack. Both of your suggestions would be an improvement, however. Bob NO6B
Re: [Repeater-Builder] Re: Mastr II mobile in repeater service Noise in receiver
At 4/12/2007 06:26 PM, you wrote: Antenna is a Cushcraft AFM-44 4bay. feedline is LMR400 abt 50ft run. all N connectors. Dan 2 problems: one is the LMR400. If it's brand new the connectors are correct (made especially for LMR400 properly installed), it should be OK for now but expect problems later. The other, probably more severe problem is the Cushcraft antenna. Unless I'm mistaken, that model hasn't been produced in several years, so the phasing harness is automatically several years old. The braided shield of the phasing harness is not made with silver-plated coax, so it will generate duplex noise. Replacing the antenna is the only good solution. If that simply can't be done, you might be able to cure the problem by stacking several pass cavity filters on the TX to strip off as much noise off of your TX as possible. When there's no TX phase noise, there's no noise to convert back to the input to cause the scratchy noise you hear. However, IMD from other sources may still be a problem. Bob NO6B
Re: [Repeater-Builder] Re: Mastr II mobile in repeater service Noise in recei...
At 4/13/2007 11:47 AM, you wrote: In a message dated 4/13/2007 10:26:37 A.M. Pacific Daylight Time, [EMAIL PROTECTED] writes: 2 problems: one is the LMR400. If it's brand new the connectors are correct (made especially for LMR400 properly installed), it should be OK for now but expect problems later. The other, probably more severe problem is the Cushcraft antenna. Unless I'm mistaken, that model hasn't been produced in several years, so the phasing harness is automatically several years old. The braided shield of the phasing harness is not made with silver-plated coax, so it will generate duplex noise. Replacing the antenna is the only good solution. If that simply can't be done, you might be able to cure the problem by stacking several pass cavity filters on the TX to strip off as much noise off of your TX as possible. When there's no TX phase noise, there's no noise to convert back to the input to cause the scratchy noise you hear. However, IMD from other sources may still be a problem. Bob NO6B Bob I'm a little confused by this analysis. If the copper phasing harness oxidizes and starts generating noise, I was under the impression that the noise point is for all practical purposes a low level broadband noise generator. If it is broadbanded, how can additional filtering on on the TX side dissipate what is essentially low level on-channel receiver noise. What am I mising here? Thanks Bruce K7IJ The oxidized braid doesn't actually generate broadband noise on it's own. What it does is act as a nonlinear mixing element to mix the TX carrier with its own phase noise. Obviously there's nothing you can do about the TX carrier itself, but you can filter the adjacent noise at the TX output to a certain degree with pass filtering, thus reducing the amount of noise available for conversion to the RX input. I tried adding a pass filter on a system that had only a notch duplexer. This system had no desense most of the time but occasionally it would get severe intermittent, scratchy desense due to the loose hardware around the antenna (it's mounted on a crank-up tower). Adding the pass cavity to the TX eliminated about 95% of the problem. Bob NO6B
Re: [Repeater-Builder] Poor Mans Repeater Project anyone?
At 4/11/2007 11:02 AM, you wrote: Re: Poor Mans Repeater Project anyone? Would some of you group members be interested in a Poor Mans Repeater Project as described below? The project goal would be to construct a simple repeater using various/mixed radio parts. We as a group would talk about various portions of the repeater during actual construction of a project by at least one or two (probably more) group members. I'm just starting on my 3rd GE MVP VHF portapeater. #1 is locked up in a tower; I guess that makes it a permapeater now. No regrets - it's still accessible has on-off control via an open-drain output of a controller on a co-located 440 system, plus it was cheap: radio mobile duplexer were free, IDer was an old Autocode board out of my junkbox, homebrew audio/keying circuit used pre-existing GP9 antenna with crossband diplexer. Only thing I remember explicitly buying for the system was the crystals. #2 got pressed into standard 600 kHz repeater service (sans mobile duplexer, of course). Anyway, I started on #3 by grabbing a VHF MVP out of the garage throwing in on the bench. I test before I do any converting so I don't waste time converting a dog. I pay particular attention to the TX, as RXs are easy to swap but if the RFPA has a problem it's easier to just use another chassis with a working RFPA. It tuned up fine: 32 W on 144.93, 0.35 µV for 12 dB SINAD @ 147.585. One coil in the IF section was way off for some reason, but everything's playing fine now so time to start the conversion (convert to duplex bring all needed I/O out the rear 10-pin system connector). I'll also be installing the VHF UHS preamp I bought from Kevin at the '05 Hamvention to see if it will handle the mobile duplexer isolation. I need to squeeze as much sensitivity as I can out of this one, even if it means adding an additional filter, sized within reason (not a 10 1/4 wave Motorola bottle!). Bob NO6B
Re: [Repeater-Builder] Re: LMR feed line revisited and revised!
At 4/6/2007 09:49 AM, you wrote: Hi Skip, Interesting Comments. Have An UHF repeater using PL259 Connectors on the Motorola T1501AL Cavitys, which has UHF connectors on them. There is no Desensing at all. Are they silver-plated? Bob NO6B
Re: [Repeater-Builder] Radio Words IWCE This week!
At 3/26/2007 09:30 AM, you wrote: Re: IWCE Once again a quick blurb about the Las Vegas located IWCE (two-way radio) Convention. Drop me an email direct (very quick like) If you need free tickets to save the $60 each entry fee... which you could spend on junk food. FWIW Roger Coude VE2DBE, author of Radio Mobile, will be attending IWCE this year. Wish I could go, but have my plans set on Dayton in 52 days. Plus you might get to meet me.. the short fat guy with red hair. Funny, not what I remember; guess that's age setting in... Bob NO6B
Re: [Repeater-Builder] Re: Power-Pole connectors
At 3/24/2007 02:57 PM, you wrote: Reasons not to solder PowerPoles: 1) It is very hard to control the wicking of solder into a stranded wire. Allowing this to happen can create a failure point in applications where vibration is present. And there can be a surprising amount of vibration in a rack mounted piece of electronic gear. Funny, that's the reason I don't like crimping. I guess there's no solid solution (pun intended). 2)Heating up a metal object that is intended to function as a spring loaded contact changes the metal and makes is softer. This is not conducive to reliability. Doesn't it have to get hotter than normal soldering temperature for a few seconds in order to have an effect on elasticity? 3) A properly crimped powerpole more reliable than a soldered powrpole. Overall I've had better reliability with soldered connections, but that's just me. 4) Aircraft connectors are not soldered. Be thankful of that the next time you are in a airliner at 30,000'. Crimping is much faster than soldering, hence less expensive making $128 + taxes roundtrip airfare from SoCal to MDW (for Dayton) possible :) Bob NO6B
Re: [Repeater-Builder] Re: Preamp and attenuator
At 3/22/2007 09:34 AM, you wrote: Bob, How would we know if the preamp is nonlinear or not? Only way to know for sure is to connect a spectrum analyzer to the output of the preamp look for anything greater than, say -15 dBm. The advertised 1 dB gain compression point (P1dB) for these preamps is +12 dBm, though other brands I've measured clocked in a bit lower than this (+7 dBm) so unless you measure it I'd assume the worst. If it's oscillating you'll see a very strong continuous signal, possibly near the 100 mW level so start the spectrum analyzer on a high reference level with some internal attenuation. Bob NO6B
Re: [Repeater-Builder] LMR feedline revisited and revised!
At 3/22/2007 11:58 AM, you wrote: I prefer to use 300 ohm twinlead and connect it right to the screw terminals on the back of the repeater. No connectors, no dissimilar metals- and the taller the tower the larger the radiator! Under ideal conditions twinlead doesn't radiate at all. However, anything that unbalances the line will cause it to radiate, including running it past another conductor in close proximity. Also, I'm not aware of any high-gain omni antenna designs that are balanced except possibly the vertically stacked dipole arrays. But then you'd have to design a corporate feed network out of twinlead too. Yikes!! Bob NO6B
Re: [Repeater-Builder] Amateur Radio Grade Equipment
At 3/16/2007 10:44 AM, you wrote: I myself have pretty much given up on Amateur Grade Equipment all together. It doesn't matter who makes it, they all have relaxed their standards. It all started when I purchased a Yaesu VX-7R. After I feel the same way, except that in most cases commercial equipment is not an option for me. I need VFO mode, which the commercial radios just won't do. Being locked into a couple dozen channels isn't my idea of ham radio; I want to be able to dial around listen to whatever I want. My solution has been to stick to some of the older (late 90's vintage) equipment. Alinco's current offerings are unacceptable to me, but their DJ-G5T DR-605 are two of the best radios in their respective categories. On the 2 meter side, the Kenwood TR-7950 has served me well as an IMD-free mountaintop remote base for many years. Unfortunately it's old enough to not have reasonable CTCSS encode capability (only 3 pre-set tone freqs.). I'd rate my FT-8900 as marginally acceptable, unless the current trend changes that will be the last new radio I ever buy. Sadly, the waning quality of the newest ham gear has somewhat eroded my overall interest in the hobby. Bob NO6B
Re: [Repeater-Builder] Coax for cabinet and for feedline - other than hardline
At 3/16/2007 01:12 PM, you wrote: Gentlemen, Is LMR-400 a good coax to use for my 70cm repeater feedline. No. I would like to keep my new Daiwa CN-801 (UHF connectors) SWR Power meter in the Tx line permanently. Is this a good idea? It is No; the power sensing diode may generate IMD. I am using a Diamond X510MA (17 feet long with a UHF connector) dual band antenna at 65 feet high. Should I be using a different antenna for my repeat operation? No. For a home-based repeater you probably want all the on-the-horizon gain you can get. Bob NO6B
Re: [Repeater-Builder] Re: fixed-audio?
At 3/14/2007 05:27 PM, you wrote: On 3/14/07, nj902 [EMAIL PROTECTED] wrote: Another post suggested checking the frequency response of your repeater. Definitely - do that. Try it a various deviations. You may be surprised at how ugly it gets. Sure would be nice to see ARRL labs do a shootout of repeater controllers with tests like this one... they spend days and days (and page after page) testing out $10,000 HF rigs... My experience has been that the controller has little to do with overall repeater audio quaility, what few deficiencies I've found in them (mainly the input coupling deemphasis capacitors in LinkComm controllers being too low in value) are easily corrected. What's most important is how the controller is coupled to the radios that the levels are properly adjusted. Bob NO6B
Re: [Repeater-Builder] Re: Flat Audio
At 3/15/2007 09:48 AM, you wrote: Then there is the adjacent channel interference they create. There is nothing you can say that will convince me that any repeater can solve that problem. Wide doesn't always equal an interference problem. ..if your channel spacing is 20 or 25 kHz. At 12.5 or 15 kHz spacing, an overdeviated signal is going to put a significant amount of energy into the adjacent channels, if there's something there, interference is very likely. It's true that it's quite difficult to get all the users' radios down to less than 5 kHz deviation, so deviation limiting post-limiter low pass filtering is important on repeaters operating on narrow spaced channels. On 2 meters in SoCal the standard is 4.2 kHz peak deviation 20 dB down @ 4.4 kHz modulating frequency. Yes it hurts the audio fidelity a bit but ya gotta give up something when you go below 20 kHz channel spacing. Bob NO6B
Re: [Repeater-Builder] Re: Flat Audio
At 3/15/2007 12:48 PM, you wrote: Yes, you should de-emph the audio going to a DTMF deocder and autopatch, and pre-emph the audio coming from the autopatch is using a flat audio response system. ...hence the source of all the confusion: to build a flat audio response system you need to put de-emphasis on this that pre-emphasis that the other so as to shape the flat audio coming in going out so that it's actually pre-emphasized. -( ) Bob NO6B
Re: [Repeater-Builder] fixed-audio?
At 3/14/2007 10:43 AM, you wrote: Guys, an observation: I hope the discriminator equals flat folks appreciate the mess they've created with our lexicon. Rodney has now been forced to say it like this: This chart shows pin 11 as Filtered Audio Out which is de-emphasised audio pre-volume control. If you want straight discriminator (flat) audio out then I think you can change the setting for this pin via the RSS. De-emphasized audio is, of course, flat audio. There is no tilt in its response. Correct. If this is so, then what is straight discriminator (flat) audio? Audio recovered from a frequency modulation detector that hasn't been shaped to remove the pre-emphasis from the transmitted modulation. Unshaped, unfiltered, but not flat. Since de-emphasized audio is different from discriminator audio, they can't both be flat. Correct. De-emphasized audio is the flat audio. Enough revisionism already. Terms like flat audio repeaters are misleading to anyone not intimately involved in their construction. Correct. Instead of flat audio, a term such as unshaped, unprocessed and/or direct FM should be used instead. Bob NO6B
Re: [Repeater-Builder] DCI Filters in front of Mountain Top Remote Base Radios
At 3/5/2007 09:08 AM, you wrote: While the DCI 2MHz filter is nice to have in service... it's not going to be nearly enough on a real busy mountain top. You mention the problem signals as being same band 2-meter signals. So without some serious filters there will be probably no soup for you. Can't filter what you also want to listen to. This was a frequency-agile remote base. There were some 2 meter repeaters on site as well we accepted what interference there was when they were TXing, but the interference I'm referring to was without any of those repeaters TXing. In comparison, I also had a Kenwood TR-7950 remote base at a different location but having a similar RF view of the LA basin. Never heard a burst of IMD on any frequency it was set to in the 15 or so years it was in service. Filtering? None. I'm having the same DCI not enough problem at one of our locations. At what frequency is it not enough? 151-152 MHz? Not much between there 2 meters very little below 2 meters until you get to ~137 MHz or so, so for most applications it should do the job. Bob NO6B
RE: [Repeater-Builder] Re: 220 repeater receiver recommendations?
At 2/28/2007 08:19 AM, you wrote: Bob You seem to want to lump what is characteristically a complex impedance (R+or-jX) into a single number in order to simplify your argument that a non conducting RF output transistor is an open circuit because the transistor is not having any RF drive to the base (as in a class C amp with no current flowing in the collector / emitter circuit), and ignoring the Xc or XL remaining which will and is being transformed to an impedance different than the impedance originally designed to operate into as a load (50 ohms). Even then your argument again fails because the transformed complex impedance (+or-jX) will result in a source impedance from the transistor into something also complex, either capacitive or inductive, with little or no resistive component, and is never seen or sourced as a high impedance by any stretch of the imagination. I use the term high impedance loosely here to mean no resistive component, hence quasi-infinite VSWR, low return loss, mag. S11~=1 or however you want to put it. In reality, the impedance at the collector of the transistor is going to be pretty high. Yes it gets transformed around the Smith chart to a capacitance, through a short @ 1/4 wavelength, then inductive back to an open as you move away from it but I think that's irrelevent to this discussion. Why do you think that this (high impedance) is the case? Even in RF amplifiers operated as class A or AB, there is always current flow thru I'm talking about class C amplifiers, the ones normally found in repeater RFPAs. They draw no current when not TXing. Bob NO6B
RE: [Repeater-Builder] Re: 220 repeater receiver recommendations?
At 2/28/2007 08:19 AM, you wrote: Bob You seem to want to lump what is characteristically a complex impedance (R+or-jX) into a single number in order to simplify your argument that a non conducting RF output transistor is an open circuit because the transistor is not having any RF drive to the base (as in a class C amp with no current flowing in the collector / emitter circuit), and ignoring the Xc or XL remaining which will and is being transformed to an impedance different than the impedance originally designed to operate into as a load (50 ohms). Even then your argument again fails because the transformed complex impedance (+or-jX) will result in a source impedance from the transistor into something also complex, either capacitive or inductive, with little or no resistive component, and is never seen or sourced as a high impedance by any stretch of the imagination. I use the term high impedance loosely here to mean no resistive component, hence quasi-infinite VSWR, low return loss, mag. S11~=1 or however you want to put it. In reality, the impedance at the collector of the transistor is going to be pretty high. Yes it gets transformed around the Smith chart to a capacitance, through a short @ 1/4 wavelength, then inductive back to an open as you move away from it but I think that's irrelevent to this discussion. Why do you think that this (high impedance) is the case? Even in RF amplifiers operated as class A or AB, there is always current flow thru I'm talking about class C amplifiers, the ones normally found in repeater RFPAs. They draw no current when not TXing. Bob NO6B
Re: [Repeater-Builder] Re: 220 repeater receiver recommendations?
At 2/26/2007 08:27 AM, you wrote: Bob Dengler wrote: At 2/23/2007 12:50 PM, you wrote: With respect to using the GE MII mobile frame for repeater applications: 1. Can you say categorically that there is sufficient TX/RX shielding to prevent any desense at any power level the conversion is capable of operating? In my experience, yes. In fact, we have had several repeaters that the sensitivity actually gets BETTER with the transmitter active. (due to the correct 50 impedance being applied to the TX port of the duplexer) Hmmm, that sounds rather unusual. I can see the non-50 ohm impedance at the TX port pulling the notches on the RX side, but I wouldn't expect it to affect the much broader RX pass response to the point of degraded RX sensitivity. I'm assuming he had the antenna relay in line, and it was still switching when keyed/unkeyed. I would either hardwire the relay in tx mode, or jumper it out. Bypassing the relay shouldn't have an effect on the TX output Z when not TXing, as the final RF output transistor is going to look like an open too. Bob NO6B
Re: [Repeater-Builder] Re: 220 repeater receiver recommendations?
At 2/23/2007 12:50 PM, you wrote: With respect to using the GE MII mobile frame for repeater applications: 1. Can you say categorically that there is sufficient TX/RX shielding to prevent any desense at any power level the conversion is capable of operating? In my experience, yes. In fact, we have had several repeaters that the sensitivity actually gets BETTER with the transmitter active. (due to the correct 50 impedance being applied to the TX port of the duplexer) Hmmm, that sounds rather unusual. I can see the non-50 ohm impedance at the TX port pulling the notches on the RX side, but I wouldn't expect it to affect the much broader RX pass response to the point of degraded RX sensitivity. I have experienced this phenomenon before, but without a duplexer (or anything except a load for the TX) connected to the radio. In my case it was due to leaking the RX RF from the signal generator (in this case just an HT) through the radio's case the RF taking different paths through the radio to the RX between the TX on TX off conditions. Sometimes the RX would degrade with the TX on (as expected), sometimes it would improve. Both conditions were eliminated when the sig. gen. was properly coupled to the RX's RF input. Bob NO6B
Re: [Repeater-Builder] Re: Antenna gain specs
At 2/20/2007 07:11 AM, you wrote: Paul Holm wrote: Reading the replies that mentioned gain specs, I can't help but think of our last ham club meeting. An older member persuaded the club to replace the VHF repeater antenna with a Diamond X500HNA rather than a DB-224 because the Diamond has 8.3 dB gain. And even worse is that the rest of the club was stupid enough to listen... When it comes to gain, the Diamond probably really has 8.3 dBi. The real difference between the two antennas is pattern shape (DB224 has a cleaner pattern; the dual-band antennas have deeper nulls below the horizon), and of course the mechanical ruggedness of the DB224. Bob NO6B
Re: [Repeater-Builder] Re: Icom portable repeater help
At 2/13/2007 08:22 AM, you wrote: Thanks for your input, I was hoping to hear from someone who had experience with this kind of rig. I've been trying the vertical antenna separation tactic, which *in theory* puts the antennas in each others' nulls, but I think the reality is that there's enough pattern distortion, signal reflection, etc to make it unworkable. I just was looking for a sanity check before spending the bucks on the duplexer. Brian K9JVA I agree with using a duplexer as opposed to split antennas. As Adam pointed out in a previous posting (at least in the order I'm getting them from Yahoo), sufficient vertical separation in a portable operation is difficult, while with enough coax or split sites you may be able to get enough horizontal separation, you'll need a lot more real estate to pull it off, or will need to use directional antennas so as to get a null between the two. I did this a long time ago on one of my first repeaters, a 2 meter system using a tube-type radio (clean TX, reasonable RX dynamic range), 1 pass cavity a directional antenna omni. The problem was I only had usable coverage in the direction the beam was pointing (~90 degrees away from the omni), plus I was constantly tuning the TX (about once every week or two) to keep the noise out of the RX. Using a duplexer will give you the maximum possible coverage from your limited antenna height space. Bob NO6B
RE: [Repeater-Builder] Advanced Receiver Research Preamp 144-148
At 2/11/2007 08:27 PM, you wrote: Ponder this Bob (and anyone else). Assume the preamp input is connected directly to the output port of the isolator. For the sake of argument, say that the preamp has a NF of 0.5 dB, and 6 dB input return loss. The power transfer from isolator output to preamp input would be 75% for 6 dB RL; the other 25% of reflected power was lost/dissipated in the reject load. Wouldn't it be mathematically correct to say that there was effectively 1.25 dB of additional loss ahead of the gain stage, and therefore the noise figure would likewise then be 1.25 dB worse (i.e. 1.75 dB)? Yes? No? Maybe? No. The reason is that the noise figure is specified for a 50 ohm input feed to the preamp, IOW the noise source used to test the preamp is 50 ohms, so any power lost due to mismatch at the preamp input is already taken into account in the measurement. Bob NO6B True that the noise figure is specified for a 50 ohm input but that is for a non reactive 50 ohm input. Once you hook it to a cavity or antenna etc. you no longer have a pure 50 ohm input so the noise figure may not be the same. 73 Gary K4FMX True, but the original question was if the noise figure of a preamp was degraded by the poor input match looking into the preamp itself, the answer is no. Feeding the preamp with an impedance other than 50 ohms yields unpredictable results, if the preamp is not unconditionally stable, it can oscillate. Chip Angle guarantees his PHEMT GaAsFET preamps to be unconditionally stable across all input impedances, IOW the entire Smith chart (see http://anglelinear.com/gaasfet/gaasfet.html). I don't know if ARR makes the same claim. Bob NO6B
RE: [Repeater-Builder] Advanced Receiver Research Preamp 144-148
At 2/12/2007 03:05 PM, you wrote: True, but the original question was if the noise figure of a preamp was degraded by the poor input match looking into the preamp itself, the answer is no. Bob, Actually, my question wasn't in regard to the NF of the preamp itself, but rather the resulting NF (system NF) due to the mismatch(es). I'm not in agreement with the system NF being independent of the match. In the example I gave, where you have a non-ideal (i.e. lossy) feedline connecting the source device (such as an antenna) to the input of the preamp, VSWR on the line is going to increase the losses on that line, thereby increasing the system NF. My contention is that if the preamp were tuned to provide a better input match, even at the sacrifice of a few tenths of a dB in NF, that the resulting system NF might actually be less than in the un-tuned case. Scenario 1: Preamp = 0.5 dB NF, antenna feeding 200' of 1/2 Heliax (3 dB loss @ 450 MHz @ 1:1 VSWR), end of feedline connects to a preamp with input return loss = 6 dB. VSWR on the feedline due to the termination mismatch would be 3:1 at the load end, decreasing to 1.66:1 at the soruce end, with the resulting loss increasing to 3.9 dB. Ignoring the NF of the antenna itself, the system NF would be 4.4 dB best-case. Scenario 2: Preamp and feedline same as above, preamp input return loss now 20 dB. 20 dB RL = 1.22:1 VSWR. Line loss would increase by only 0.03 dB. System NF would then be 3.53 dB best-case. Double-check my math if you would... Maybe we're saying the same thing, only differently? Or do you still disagree with the premise? --- Jeff Your math looks sound, Jeff, except I thought 1/2 Heliax wasn't quite so lossy @ 450 MHz (~1.5 dB/100 ft IIRC?). Realistically though, not many people connect the input of their preamp directly to 200 ft. of line. Usually there's a filter ahead of it that has loss can be tuned to somewhat tune out the mismatch. All this sort of muddies the waters a bit, but theoretically in your example a preamp with a matched input would in fact yield lower system NF given the same NF specs, due to additional induced feedline loss ahead of the preamp as a result of the mismatch, not due to the reduced power transfer between the feedline preamp. Bob NO6B
Re: [Repeater-Builder] Re: Power Suplies going up in smoke...
At 1/17/2007 11:37 AM, you wrote: A long time ago I happened to find a crowbar bar made by Lambda at the local TRW swap meet. I added it to a supply without built-in OVP to add said protection to the equipment. I wonder if similar devices are commonly available somewhere? That a fuse on the output of an SEC-1223 I think I'd feel comfy using it at one of my sites. Bob NO6B Bob, These crowbar circuits are quite simple to design and build. They usually consist of a large SCR, a zener diode, one resistor, and an optional capacitor. Of course a fuse upstream somewhere is a great idea, too. A heat Yes, I know - I've designed built a few for some pricey amplifiers we use at work. I'm just looking for something I can slap on an existing P.S. without having to worry about building, packaging etc. sink is not necessary because of the very short duty cycle. Actually, some heat dumping is required since when they fire they sink several amps of current do have a finite voltage drop across them. Not much, but enough to need a little heat sinking. Bob NO6B
Re: [Repeater-Builder] Power Supplies going up in smoke (non filtered)
At 1/16/2007 08:57 AM, you wrote: Re: Power Supplies going up in smoke (non filtered) Which makes the case for an overvoltage protection circuit in most equipment locations. According to the Samlex web site, both the SEC-1212 SEC-1223 have overvoltage protection. They don't say what kind though. I just shot an e-mail off to Samlex requesting that info. Bob NO6B
Re: [Repeater-Builder] Re: temperature control circuit
At 1/11/2007 08:38 AM, you wrote: Thanks for sharing your circuit, Bob... Have you done any measurements to see how constant the temperature is maintained over time? Looks like a neat little circuit for a couple of other applications. 73, Tony W4ZT Measuring the LM34's output, it was very good: less than 0.2 °F change. Keep in mind that other applications will probably require a different feedback loop. The 400 µF cap 30 k resistor I removed across the 100 k resistor were probably for controlling much larger systems with longer time lags between the heater sensor. Bob NO6B
Re: [Repeater-Builder] Re: temperature control circuit
At 1/11/2007 06:48 AM, you wrote: The 1/4 watt heater resistor LM34 temperature sensor are mounted on the same side of the crystal but separated as far apart as possible. I forgot to mention that thermally conductive epoxy was used to mount the LM34 51 ohm 1/4 watt heater resistor onto the crystal. Bob NO6B
Re: [Repeater-Builder] Re: WTB: GE EXEC II 66 Split receiver for mobile radio
At 1/8/2007 02:03 PM, you wrote: Actually I have several 56 splits. When I ordered the xtal, I ordered for high side injection, and it does not want to tune up real well. Put a 147.78 LSI, and it tunes to better than -110 dBm. So this is the reason I want to try a 66 split and see if it will do any better. Mathew Mathew: The 56 split RXs were made specifically to cover the 2 meter band, so you'd be better off ordering low-side LO crystals for those receivers instead of switching to 66 RXs. 66s are much more common, so if you still decide to switch I'm sure there are many here that will gladly accept an even trade :) Bob NO6B
Re: [Repeater-Builder] MVP - PLL
At 1/5/2007 07:47 AM, you wrote: Mention was made of how to deal with compensation. I've built ovens of various types, and even used PTC thermistors soldered directly to the case of the crystal as a heater, with good results. I think Bob NO6B did the same - you QRV Bob? Yes, I've been soldering 50 °C PTC thermistors to crystal cases for some time. On my last project using a rather unstable crystal I discovered that the PTC thermistors don't provide as much thermal stability as I thought (transition not sharp enough?), so I built up a feedback controller based on a design out of an old National Semiconductor databook using a dual op amp. I used thermal epoxy to mount a 51 ohm heater resistor LM34 temperature sensor onto the crystal. The circuit is able to hold the temperature at the LM34 within +/- 0.2 °F. Now the only thermal drift I see is due to the temperature effect on the oscillator transistor on the exciter board. Bob NO6B
Re: [Repeater-Builder] Need: 131.8 Versatone for GE EXEC Board 190430740G, also information
At 1/4/2007 05:57 AM, you wrote: n9lv wrote: I am in need of at least five 131.8 versatone boards for the following GE tone board. Also, I need to know, are these board just encode, and is there a way to make them decode. I put one in one of the radios, it does send pl out the transmitter, however I do not get any audio from the speaker out of the receiver. Problem I am having is that the GE converted radios will not allow the PL tones to pass through them. I can take the repeater out of PL and the radios work just fine, and the audio is just fine. Any sugesstions? Thanks Mathew I think you are you using these radios for voting remote receivers? If that's the case, are you sure you want to introduce yet another PL response time into the equation? If not, consider FM'ing the transmitters, and installing some sort of audio processor designed to do the job of clipping and HPF'ing that fits the situation. While FMing definitely improves the low-frequency modulation performance of PM exciters, I've experienced good performance with my stock MVP PM exciters. I know from Dave Karr's experiments (or was it Virgil at S-Com, can't quite remember who did the tests a while back) that the harmonic distortion at low modulating frequencies and high deviation levels is a bit high. However, CTCSS deviation levels are quite low in practice (should never be more than 1 kHz). If the output from the RX discriminator is de-emphasized so as to match the pre-emphasis curve of the phase modulator, a very flat audio response that includes the CTCSS frequency range can be obtained. Basically this means lowering the break point of the de-emphasis network from the usual 300 Hz to just below the low end of the CTCSS range (40 Hz or so). The AP-50 is one such animal. Most commercial equipment audio chain in good from only 300 to 3000 cycles; it won't pass PL and it won't pass the high-end audio that the voter relies on to properly vote. The phase modulators that most of this equipment utilizes won't properly follow audio that is recovered from the discriminator, and is why I choose to install a real FM modulator in the radio set. A better sounding, better working radio will result; one that is transparent to the system. I have never tried to FM a EXEC II; we've always used MASTR II's for remote satellite receiver - link-back transmitter combo's, but, I don't see why it can't be done. IMO the AP-50 is an excellent final output processor that enables a near-perfect balance between keeping the output clean and preserving repeat audio fidelity. However, for a remote receiver link I think you'd want to make it a 1:1 link with no limiting or filtering whatsoever. For that you could simply FM your TX, or use the CG HI (direct to the PM modulator) apply the de-emphasis as described above. I've done this for my system which has a total of 3 links in the repeat path have been told by some local FM purists that it sounds quite respectable. My ears do detect a bit of subtle low-pass filtering taking place somewhere; I believe it's due to the combined low-pass roll-off of each RX in the system as a result of the IF filtering but I could be wrong. Bob NO6B
Re: [Repeater-Builder] Newbie Information Time - Mystery Signal
At 12/14/2006 08:34 AM, you wrote: In my opinion, is a slight flaw in the voice operation on 144.39 MHz below ... the FCC requires you to monitor the frequency in a non-CTCSS mode prior to transmitting. Not quite. The FCC requires you to make sure the frequency is not in use before TXing, the idea being you don't interfere with communications in progress on said frequency. Packet, by design, automatically monitors the frequency so as to minimize collisions. If on occasion you accidentally stomp on a packet, no biggie: it automatically retries a few seconds later. So occasional CTCSS-protected voice transmissions on 144.39 wouldn't really be a problem, although an extended rag-chew would be. Bob NO6B
Re: [Repeater-Builder] Re: how to build a very simple repeater controller
At 12/7/2006 10:54 AM, you wrote: It normally takes two 555 timer chips for a basic cor function. One timer is set up to add tx tail/hang time and the other to ensure the exceeded tx time-out time function shuts the transmitter down. A lot of people get cheap and replace the tail timer with a resistor cap method, which is not nearly as cool as a well done 555 circuit. How about using good ol' op amps? I like that approach because almost the entire basic controller can be implemented using a single chip: 2 op amps for hang time TOT, 2 left for audio processing. Add a JFET for squelch audio gating you're done. The TLV2374 features rail-to-rail operation so it makes a good comparitor, yet also has good audio distortion characteristics so long as the output stays at least 1.4 V away from the positive supply rail. It's a good choice for such multi-purpose use. Bob NO6B
Re: [Repeater-Builder] GE Exec II Conv. Max audio 1.5 KHz Dev, how can I increase it
At 11/29/2006 09:01 AM, you wrote: Any chance of a source for the op amps? I called our local electronics parts dealer and he says he is not able to cross reference them. Thanks. You can really use just about any op amp, even the old 741. For that one the output is pin 6, not pin 1, the V+ supply goes to pin 7 instead of 8. I recommended the TLV2372 or LMC6482 because they're less prone to crossover distortion. If you want to order the good ones: TLV2372: Digikey: 296-12219-5-ND $1.30 Newark: 76C7976 $1.30 Mouser: 595-TLV2372IP $1.30 LMC6482: Digikey: LMC6482IN-ND $1.82 Newark: 41K2662 $1.92 Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/27/2006 12:26 PM, you wrote: Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It's the LO multiplier chain that you're hearing. 145.460 * 3 + 11.2 = 447.580 (447.575). After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 10:19 AM, you wrote: You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. I forgot to mention: the reason you don't hear it on TX on an unmodified Mastr II is because the RX OSC 10V is cut off during TX, so there's no RX LO when TXing. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 10:49 AM, you wrote: Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460... If Nate has a neighbor that likes to listen to 152.925, then yes. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 10:49 AM, you wrote: I forgot to mention: the reason you don't hear it on TX on an unmodified Mastr II is because the RX OSC 10V is cut off during TX, so there's no RX LO when TXing. Bob NO6B I don't have a manual in front of me, so I have to ask the question here. If the 10V to the Rx oscillator board is cut off during Tx, how could you put a 5C element in the Rx and an EC in the Tx and still have the Tx EC element be compensated by the Rx 5C while transmitting? The Rx 5C ICOM would need the 10V in order to generate the compensation voltage. Or am I forgetting something? Nothing forgotten - the ICOM still gets 10 V, just not 10 V for the oscillator. There are two separate 10 V feeds to the RX: one for the LO oscillator one for everything else. Bob
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 12:23 PM, you wrote: Bob Dengler wrote: At 11/28/2006 10:49 AM, you wrote: Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460... If Nate has a neighbor that likes to listen to 152.925, then yes. Bob NO6B It's reealy weak, Jeff. I'll probably move the ICOMs into a Station just to get a little more shielding first just to see if it helps, and then order crystals if that doesn't work... Guess I could just move the RX ICOM first and see how bad it is before futzing around with tuning the TX side. It probably doesn't help that the cables going to the PC aren't coming out of the case via any kind of feed-through caps, etc... bad Nate, no donut. They probably make nice antennas at VHF. :-) If it's in a Station, I can pull the audio and and signals needed off the backplane, which have already been nicely isolated from the guts of the radio with the built-in feed-through caps, etc - of course. I was just wanting to not waste a complete Station shelf on a link radio that only needs 250mW to be full-quieting or darn near close to it. If you have an MVP lying around, you might have better luck with it. It's I/O connector has feedthrough caps on each line, just inside the case. I do hear LO leakage out of them too, but not quite the level you experience. Bob NO6B
Re: [Repeater-Builder] GE Exec II Conv. Max audio 1.5 KHz Dev, how can I increase it
At 11/28/2006 12:31 PM, you wrote: I have taken a UHF transmitter and combined it with a VHF receiver for a crossband split. The very maximum deviation that I can obtain from the radio is about 1.5 KHz. This is with the pot turn all the way up. Mic high is being fed into a 1.0 MFD cap through a 15K resistor to the high side of the volume control. The audio is clear, just not all that loud. Mathew I think the output Z of VOL/SQ HI is too high to use for direct feeding the MIC HI input of the G.E. TX. In addition, you need to de-emphasize the audio as the VOL/SQ HI audio is still pre-emphasized the TX audio is also pre-emphasized again. This means you need a buffer (op)amp to de-emphasize the audio drive the 600 ohm mic input. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 01:06 PM, you wrote: Nothing forgotten - the ICOM still gets 10 V, just not 10 V for the oscillator. There are two separate 10 V feeds to the RX: one for the LO oscillator one for everything else. Bob Confused. The ICOM *is* the oscillator, and it only has one 10V input pin. Or are you saying that the multiplier chain is what gets turned on and off? --- Jeff I don't have the manual here, but on every radio I convert to duplex operation I have to strap the RX OSC line to the 10 volt feed, otherwise the RX signal goes away (replaced with noise, not a muted RX) everytime I key the TX. I'm assuming here that without 10 V on the RX OSC line there is no RX OXC, hence no LO. Bob NO6B
Re: [Repeater-Builder] Re: Has anyone interfaced a Yaesu FT-8500 to be a remote base on a repeater?
At 11/16/2006 12:46 PM, you wrote: At 11:18 AM 11/16/2006, you wrote: I would say that depends on when the radio was made. Older Yaesu's, such as the FT-757 and even the FT-727 had a CAT interface which allows data from a computer to set the operating parameters of the radio. Other radios in the Yaseu line, Such as the FT-5100 have a few lines for the buttons, like band sellect and channel up and down. Which can allow 'poor mans remote base'. Others take a serial data stream down the mic jack to do control of the radio. You would have to get a logic analyzer or digital storage scope to disect the protocol though. The FT-8500, 8800 and 8900 don't allow for serial commanding of the radio on the fly, i.e. no CAT interface. Are you sure about the FT-8500? I was sure I saw a reference to the CAT interface in the 8500 manual. Bob NO6B
Re: [Repeater-Builder] wind up tower noise
At 5/25/2006 08:01 AM, you wrote: Has anyone experience with eliminating noise fom the metalwork of a wind up tower? Our tower has 4 sections and is of the type where all sections raise at once with a single cable pulley system. The Machine is a Nokia BRS150 using a Sinclair Duplexer on 145.7625/1625 Antenna is Jaybeam Folded Dipole with its own RG214 tail into 60 ft of LDF450. When you shake the trailer mounted tower there is severe crackling on weak signals. The three stays have been tightened up as far as possible. Any Ideas on how to kill this noise guys? I help maintain a system using a similar tower configuration. Right now we have no desense problems at all. The duplexer has 3 pass-notch cans on the RX, and 2 pass-notch cans + 1 pass only on the TX. The antenna is the 8 ft. TRAM dual-band sold by Repeater-Builder, it's mounted ~15 ft. above the top of the tower on a mast. IMO the key to eliminating desense when using a less-than-ideal tower is to keep the TX noise to a minimum, raise the antenna well above the top of the tower to prevent coupling to the loose sections, and choose an antenna that's well decoupled from the feedline for the same reason; apparently the TRAM does well in this regard. I'm not familiar with the Jaybeam folded dipole but if it has no balun, then the problem could be RF flowing down your feedline coupling into the tower. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Mastr Executive II Help on changing 440 Xcvr to 2 Xcvr for Crossband Operation
At 5/24/2006 03:51 PM, you wrote: I have a slew of Ge Mastr Executive II radios that I want to take the 2 meter reciever and place into the 440 Mhz transmitter to make them crossband for link radios for remote recieve sites. These are the Canadian versions so no mods are needed for the units to work in the ham band. No mods are needed for U.S. versions either, so long as the last 2 numbers on the model plate are 88 (UHF), 56 or 66 (VHF). 56 is the VHF model that's actually spec'd to cover 2 meters, but the 66 radio should cover it all too. I've had some issues with some 66 exciters not quite making it down to 144.39 for APRS, but above 145 you should be OK. What you want to do sounds real easy: just swap the RXs between 88 66 radios. Also, if someone has a link or possibly a location to be able to identify which radio is what by the COMB number this would be helpful as well. This should help: http://www.hallelectronics.com/getech/053.htm Also if anyone has a service manual they would be willing to let go of, I could use one of them as well. Check the Mastr list of PDF'd manuals at the Repeater-Builder website. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] midland 13-509 tx freq stability... cap change?
At 5/23/2006 02:06 PM, you wrote: If you decide to use an 85 deg C oven, you must get the crystal cut for that temperature. Yes, I've noticed some short-term aging problems with crystals run at 50 C. In one case the crystal was held at 35 C for a couple of years, then sat on the shelf for a few more. When put back into service at 50 C, it drifted up about 2 PPM over a period of a couple of days. So it seems that even moderately heated crystals need to be aged at their operating temperature. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] midland 13-509 tx freq stability... capchange?
At 5/23/2006 05:20 PM, you wrote: I have found the Motorola 85 degree C gold oven to be quite stable - the earlier black 65 degree C oven wasn't. Stability wasn't an issue in this case. I was using a temperature controller with feedback; the sensor on the crystal was held within +/- 0.2 degrees F. Turns out that with that level of crystal temperature stability, the primary drifting component in a G.E. MVP is the oscillator transistor. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Dayton webcam
For those who can't be there, mms://66.231.242.90/video Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Good mobile for solar site
At 5/16/2006 10:58 AM, you wrote: ve7ltd wrote: I am in the process of setting up a package to be taken to a solar site at 9000 feet in the rockies. I am making an internet remote SIMPLEX system, and I need a radio that would be good for the site. Some of the requirements are: 1) low current on receive 2) Adjustable and clean to 1 watt transmit power 3) stable at varying temperatures 4) Efficient on transmit 5) At least 10% duty cycle 6) Narrow-bandable would be an asset Boy, it sounds funny, but I'd be hard pressed to find anything that draws less current on receive then an old Motorola HT-200. Spec was about 11mA squelched, 40-50 or so unsquelched @ rated audio out, IIRC. TX was about 400-500mA @ abt 1-2W out. A 500mAH NiCad pack was spec'd to last at least 8-10 hours on a 10-10-80 duty cycle. Lots o'drawbacks though. Not the least of which is that ground is POSITIVE. How 'bout the HT-220? IIRC much better sensitivity, also a power miser @ 11 ma RX current as well. I seem to see a lot more of them at swap meets than the HT-200. Maybe because the latter have all been bought up by museums? True mobile radios will draw a lot more current since that wasn't a primary driver in their design, even if they're xtal-controlled. G.E. MVPs draw at least 250 mA on RX. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Help on Arcom RC-110
At 5/15/2006 10:26 AM, you wrote: Ken, how does Arcom upload the operating firmware into the RC-110? The checksum error has been present on the file I download from NetMedia for over two years, as I have been trying to get a working copy for that long. Could I get a copy of the upload program from Arcom that works? 73 - Jim Jim, I do not have any of Ken's controllers to play with, but I did try downloading the BasicX program only (downloader, compiler, editor) file (bx-setup-210-program.zip 3.992megs) and installed it without a problem. I can't say that it works as I do not have a device to load, but it does start and appears to be OK. Ed Yoho WA6RQD I purchased a complete BX-24 development system a couple of years ago had no problem uploading my program into the BX-24. I also just downloaded the downloader from http://www.basicx.com/downloads/bx-setup-210-program.zip, installed it compared the files to the ones I used during development; they're identical. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Portable Repeaters
At 5/8/2006 05:51 PM, you wrote: We can't even get real emergency groups around here to use STANDARD OFFSET UHF repeaters most of the time. Color me VERY skeptical that any more than a few people will ever truly use a wide-split portable VHF repeater in a true emergency. Overloaded, stressed out people, don't respond well to dig out your manual and figure out how to program in a 2.655 split repeater. And a large number of people wouldn't or couldn't -- sad, but true. I can't speak for emergency groups/situations, but for public service events the wide-split 2 meter repeater works very well. It does take some pre-event planning training, but at least now we have a few dozen well-trained operators with the portable repeater pair still programmed in their HTs. My feeling is that if the EmComm groups were as well trained prepared, the in-band odd-split repeater would work as well for them. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Good Radio's for Repeater?
At 5/9/2006 12:57 PM, you wrote: I've been following this thread with interest, and have a couple of points which (of course) lead to more questions. The MASTRII RF strips are the same in the repeater chassis and the mobile rigs, band for band from low band to UHF. Flexibility and convenience options (and continuous duty PA issues) aside, why is a MII repeater station better used as a repeater than a MII mobile rig? Shielding. The Mastr II mobile TX exciter sits right next to the RX LO chain couples into it. In many UHF applications this causes no problem but in high RF environments the RX can receive IMD that isn't on channel, but is a product of a strong off-frequency (~150 to 300 kHz) signal a harmonic of the TX fundamental oscillator. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Telewave TPRD-4544 Duplexer
At 4/20/2006 10:56 PM, you wrote: I am seeking tuning instructions for the Telewave TPRD-4544 Duplexer. Is that the UHF flatpack with 6 small cylindrical cavities? If so, it's a notch duplexer. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: That horrible noise
At 4/21/2006 09:09 AM, you wrote: --- In Repeater-Builder@yahoogroups.com, Ken Arck [EMAIL PROTECTED] wrote: I'd be interested in hearing the wav file you recorded, Dave But bear in mind that your comment that it's not coming from either repeater could easily be wrong. As a matter of fact, if you're running a delay in the audio path of either repeater, one of them is most definately involved. It sounds like a typical spur/mix/intermod issue to me, probably involving a 3rd party. Anyway, let's have a listen. Well, the same problem is happeing in two machines. Interestingly the one that does use a switcher to charge the battery is mine (the 85), and the problem happened on the other repeater long before I installed my switcher. The 73 uses an astron linear supply. I'm aware of the possibility of mixing with a switcher, but the problem also happens when mine is shut down. Yes, but now we're debugging a problem on your repeater, correct? If so, replace the switcher with a linear supply see if the problem continues. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: That horrible noise
At 4/21/2006 12:10 PM, you wrote: No, listen to the beginning of each audio segment. It's classic RF feedback with audio delay. Sounds like a Kendecom too. Bob NO6B I'm not sure what you mean here.. The equipment you're listening to is Daniels MT-2 VHF, with 21.5 MHz first IF. OK, I've never heard a Daniels repeater before so maybe they have similar audio characteristics (lack of low frequencies in repeated audio, soft pop from squelch audio gate when opening). At any rate, see my previous post: investigate the switching supply first. Another common culprit is site video cameras: 38th harmonic of 15.75 kHz is 598.5 kHz, so see if the interfering signal is 1.5 kHz above or below your input. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
