Re: [Repeater-Builder] Re: Would You..... tower height question
Steve S. Bosshard (NU5D) wrote: Generally 199 ft unless you are close to an airport. There is a 110 ft tower that requires registration but no painting or lighting because it is close to the Temple, Texas airport. Steve NU5D texasexpediter wrote: What is the maximum height a tower can be without falling under all the lighting, painting etc. regulations? Ditto. We've just been through the same exact issue. Normally it's 199', but if you're near an airport, there's a requirement for any tower within 20,000 ft from a runway. See: http://www.faa.gov/airports_airtraffic/airports/regional_guidance/central/contruction/part77 (watch for wrapping) -- Larry rapp at lmr dot com
Re: [Repeater-Builder] Duplexer tuning - sanity check
2d question only. If you have adjacent channel repeaters close to you, something is wrong with your frequency coordinators. 2 mtrs has enough trouble with 600 khz spacing, to expect 16 khz is ludicrous. The only solution for adjacent channel repeaters is distance. -- 73, Larry, W1HJF [EMAIL PROTECTED]
Re: [Repeater-Builder] Linking 2 repeaters
prostockcocker wrote: I have two locations that have Moto - Micor 2meter repeaters, am using a FF-800 for a controller at both sites. I have explored the idea of using a UHF repeater and link radio to hotlink the two sites, but at the time funding is a bit low. What other alternatives do I have to link the two repeaters? Thanks for the input. IRLP. See this site: http://www.irlp.net. FWIW, two of us faced the same decision and, even though we have the necessary radios and duplexers to do a full duplex link, decided to use IRLP instead. Use an old computer - software is free. -- 73, Larry, W1HJF rapp at lmr dot com
Re: [Repeater-Builder] OT: Need to find a product to develop goodwill at a tower site(s)
[EMAIL PROTECTED] wrote: Hello to All, I am starting to develop a future ham repeater relation with a tower site(s) owner and recently got a request for something unusual. The company has a fleet of VHF radio equipped vehicles. They want to pull up to a site, enter a touch-tone sequence on the mike, and open a security gate at the site. I could kludge together something, but would rather find something commercially available. Anytime I have kludged something together, I have ended up having to repair it for longer that I expected. Something with a VHF receiver, TT decode and relay contact output would be great. Any ides if this is even made commercially? I know that some fire/ambulance departments use a similar idea to open and close the firehouse door. Some also have the ability to control traffic control lights on their way to a situation. 73, Joe, k1ike Another vote for a simple garage door opener, but specifically because: you can easily buy radios which use a rolling code. If you used a simple dtmf or plain garage door opener, there would be nothing stopping an intruder from just memorizing the signal. Rolling code allows multiple transmitters, btw. If one were lost, you can deregister it from the receiver and reregister the new one. This is by far the cheapest solution and might be the best. -- 73, Larry, W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Re: A PreAmp war story
skipp025 wrote: At one location I had an ongoing problem with gasfet preamp failures. Over time I suspected the failures were done on purpose (yeah people do those sort of things). . I replaced the last blown preamp with a similar spec unit that contained internal rf bypass switching when transmit power is detected in the coax line. The system has been rock solid since the rf sense switching preamp was placed in service. No more in-line attenuator... and we can actually control the preamp from the site controller. If the preamp fails we can switch it off (out of line) while the service call is set up. cheers, skipp I'm a little confused, Skipp (nothing new there!). Are you saying that the preamp detects lightning by the rf bypass switching? After all, a repeater always transmits when it is receiving. I am assuming that you place the preamp between the duplexer and the receiver. -- 73, Larry, W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Cross-band Repeating.
Jason Cato wrote: Can someone tell me what equipment I will need to cross band repeat a Uniden SMU4525KT UHF into an Icom 2100H VHF? I want to be able to move around my property with my H/T, and still be able to get into repeaters my H/T can't reach. Also, can I use the same multi-band antenna for both at the same time with a diplexer? Or would the VHF transmission kill the UHF reception, or vice versa? Well, I can't answer all, but I can answer some. Typically, small cross-band repeaters are HALF duplex, not full duplex. That means the receiver of one is connected to the transmitter of another (on a different band). This is the way many mobile rigs which do this work. (it allows you to take a hand-held into a restaurant, for example). They accomplish their mission via a diplexer. Yes, many use a single, multi-band antenna. I had a Yaesu mobile that worked like that and now use an ICOM which does the same thing. To make this work effectively, you need a way to shut off long tails on a repeater as cross bands typically do their work based on COR (carrier operated relay). If the repeater has a long tail, you must wait for it to drop before transmitting (on the cross-band side). I don't know the specifics of either rig you mention, but the principles are all the same. Hope that helps. -- Larry W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Cross-band Repeating.
[EMAIL PROTECTED] wrote: At 4/24/2007 07:34, you wrote: Jason Cato wrote: Can someone tell me what equipment I will need to cross band repeat a Uniden SMU4525KT UHF into an Icom 2100H VHF? I want to be able to move around my property with my H/T, and still be able to get into repeaters my H/T can't reach. Also, can I use the same multi-band antenna for both at the same time with a diplexer? Or would the VHF transmission kill the UHF reception, or vice versa? Well, I can't answer all, but I can answer some. Typically, small cross-band repeaters are HALF duplex, not full duplex. That means the receiver of one is connected to the transmitter of another (on a different band). This is the way many mobile rigs which do this work. That's not the definition of half duplex that I've been using. To me, half duplex means that transmission occurs on a different frequency from reception, but only one at a time, not simultaneously. Full duplex is simultaneous transmission reception using separate frequencies. In both cases, whether the two frequencies are within the same amateur band or not is irrelevant. So one could in fact operate full duplex on a dual-band radio if it has simultaneous transmit receive capability. Bob NO6B Bob, You're right, my mistake. The OP was asking for information on cross-band repeating and that's what I gave him. I should not, however, labeled it as half duplex. -- Larry W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Re: Mastr II mobile in repeater service Noise in receiver
Chuck Kelsey wrote: LMR type cable is never recommended for duplex operation. Probably the cause. No argument or flame, but can you elaborate? Off list if you prefer. Thanks. -- 73, Larry, W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Re: Mastr II mobile in repeater service Noise in receiver
Chuck Kelsey wrote: LMR type cable is never recommended for duplex operation. Probably the cause. Never mind - got the answer further down. -- 73, Larry, W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Duplexer cavity repair
Burt Lang wrote: Hi Larry Remember me from the packet days of NEDA. You are confusing E F Johnson with Johanson Corp. E F Johnson do not make piston trimmers. of that type. The capacitors used in the Sinclair VHF Q-Circuit (BpBr) cans are 5602 Johanson caps. The key is the very high Q of these caps. The Q of the cap controls the maximum depth of the notch. Burt VE2BMQ Larry Rappaport wrote: tomnevue wrote: I bought a Sinclair Q202G 4 can VHF duplexer. The previous owner clearly spent a lot of time playing with the variable capacitors. 2 are totally ruined and I suspect the other 2 are damaged because I can't get a notch depth below 60db and it's not stable. These are porcelain (white glass) piston style marked MAV05A30. Can anyone help me with some replacements or source of supply? Any help is appreciated. Tom W2MN Maybe I can help. They were made by E. F. Johnson (don't know if they still make them), and I still might have a couple of them. The problem is I might have trouble finding them as I bought about a dozen some 15 years ago, but I'll look. They were ridiculously expensive, about US$18-20 each as I recall as they are porcelain and gold. Shoot me an email off-list. If I have any, you can have them. Hi Burt, Sure I remember you! And yes, you are right, it was Johanson Corp! Yes, I remember that Q is very important - that is why they are gold-plated ceramic piston trimmers. Well, we never heard back from the guy, so I guess it doesn't matter. 73 -- Larry W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Duplexer cavity repair
tomnevue wrote: I bought a Sinclair Q202G 4 can VHF duplexer. The previous owner clearly spent a lot of time playing with the variable capacitors. 2 are totally ruined and I suspect the other 2 are damaged because I can't get a notch depth below 60db and it's not stable. These are porcelain (white glass) piston style marked MAV05A30. Can anyone help me with some replacements or source of supply? Any help is appreciated. Tom W2MN Maybe I can help. They were made by E. F. Johnson (don't know if they still make them), and I still might have a couple of them. The problem is I might have trouble finding them as I bought about a dozen some 15 years ago, but I'll look. They were ridiculously expensive, about US$18-20 each as I recall as they are porcelain and gold. Shoot me an email off-list. If I have any, you can have them. -- Larry W1HJF rapp at lmr dot com
Re: [Repeater-Builder] Re: Tuning duplexers with sweep generator?
w6nct wrote: Actually a network analyzer works better than a combination sweep and marker generator. Remember that when you change isolation, you are also changing impedance so you need to measure swr as well. There are other ways. Read Gary's excellent post carefully. -- Larry W1HJF rapp at lmr dot com Unfortunately, I doubt that I can afford a network analyzer either; and I curently don't know how to use one if I happened to come across one to use. I'm sure you don't own one, but you might be able to rent one or borrow one, or better yet, borrow one with someone who knows how to use it! (That's not me, btw!) I don't understand what you mean when you say when you change isolation, you are also changing impedance so you need to measure swr as well. I expected that the complex impedance of the cavity might be changing as we are changing its tuning stubs; but I thought that a resonance (with a low SWR) was essentially what we are getting when we were adjusting the stubs in the cavity to peak the bandpass at the desired frequency. Am I wrong in this assumption? I don't know which duplexer you are using, but Sinclair, for example has tuned loops in the can. You can turn them to vary isolation, but when you do, you are changing impedance. I.e., you may be able to do more than just adjust the stubs. Either way, how do I set this up, and where would it fit in a test procedure? I can't tell you that unless I knew specifically to which duplexer you were referring, which model (and configuration), and then I would need to be familiar with it. I know some Phelps-Dodge and some Sinclair. I have never adjusted Wacom, TX-RX, DB Products, etc. Which post (from Gary) are you referring to; and what specifically should I be paying special attention to? His post dated 4/1/07 at 9:21 pm. He starts out Duplexer and cavities have been tuned for many years... Excellent post - one of the best I've ever read. Thx, Vern (W6NCT) -- 73, Larry, W1HJF [EMAIL PROTECTED]
Re: [Repeater-Builder] Tuning duplexers with sweep generator?
w6nct wrote: I was recently told (by another ham) that I could ONLY tune up my 70cm duplexer cavities using something called a tracking generator. Unfortunately I do not have one; and judging the prices I have seem for things with that name on the web, I doubt that I can easily budget to purchase one. For some reason, I thought that my father used to tune up resonant cavities using a sweep generator, oscilloscope, and a frequency counter; but I don't recall the exact setup he used. I inherited his Wavetek (Model #1080, 1GHz) sweep generator, oscilloscope, and frequency counter. I also have access to an IFR-1100 service monitor, if I need it (i.e., can be borrowed from a friend). Can I tune up my 70cm duplexer cavities using the equipment I have? If so, could someone please indicate the test setup and procedure. Thank-you. Actually a network analyzer works better than a combination sweep and marker generator. Remember that when you change isolation, you are also changing impedance so you need to measure swr as well. There are other ways. Read Gary's excellent post carefully. -- Larry W1HJF rapp at lmr dot com
