RE: [Repeater-Builder] New repeater Motorola or MA/COM
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Nate Duehr I'm curious to see if: 1. You're seeing the majority of failures in PA's. 2. If you're seeing other failures of some sort. (That would be odd to me, at least from our experiences with them here.) Well, I've had the PA fail about three times in the 12 years I've been maintaining it. The last time I rebuilt it all from scratch and added a couple of fans. Most recently the pots on the repeater audio board failed and had to be replaced. After that I've been having trouble getting it to key reliably via the remote keyer. The main thing is that they are for a commercial/government agency with the lack of replacement parts available, its time to update. We also have coverage issues because over the years our area has grown so it's just a natural thing to put in new stuff. Curiosity kills the cat... and what we REALLY want to know, is just where DO you Safari, Safari_Tim? :-) :-) :-) LOL.. My first travel trailer model was a Safari.. Anyway, I'd say that the Magic 8-Ball says that most folks seem to be having pretty good luck with Moto, M/ACom, and Kenwood these days. It says, Ask Again whenever I ask it about EF Johnson, Icom, Yaesu/Vertex, right now. (Oh lord, I can hear the keyboards typing up the flames now. Time to go don my Nomex underwear.) I've been asked to help spec out the new equipment and I've been stuck in a radio time warp for the last 12 years maintaining these Master II's. So I'm just looking for some direct experience with the new stuff as far as reliability and serviceability as well. It's been an interesting discussion! -Tim
RE: [Repeater-Builder] Re: Tone remote setting question
Anyone know the answer to the original question. How do you make sure you have enough high level, function, and low level guard tones at the repeater input? The way I see it you have the keyer output into the phone line to make your initial adjustment. Then the repeater has a line input as well. Keyer Odbm - telco loss -16db - repeater in -16db - -Tim
RE: [Repeater-Builder] Tone remote setting question
Two different answers about allowable loss. My line meter is marked in green for 16db, and I always heard that was reliable loss from end to end. So, what Steve is saying is if the line is flat, then setting for -10dbm @ 1000hz for 3khz deviation and all the rest will line up fine at the repeater end. What is the minimum safe hold tone level at the repeater that will keep it from dropping out on voice peaks? -Tim -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of allan crites Sent: Thursday, April 26, 2007 7:40 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Tone remote setting question Tim, The ATT spec for line loss from the sending end to the central office is 9 +- 1 dB and from the central office to the receiving end is 9 +- 1 dB. So your total loss will be 18 +- 2 dB. I need to find my tone remote manual to get the answers to your other questions. WA9ZZU Steve Bosshard (NU5D) [EMAIL PROTECTED] wrote: I believe 16 db would be terribly excessive loss for a line - maybe 6 db tops. I usually set -10 dbm @ 1000 hz for +/- 3 khz deviation. ). 0 dBm for max deviation. and let the tone levels fall into place as you have indicated. If the line measures 6 db of loss @ 1000 hz, you may want to move the hold tone from -20 dBm to -17 or -14 dBm and the remainder accordingly. Also loss may vary with tone frequency, so loss at 1000 hz may be far different from loss at 2175 hz. Best luck, Steve NU5D On 4/26/07, tim_shephard [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] net wrote: I'm working with a GE repeater, Master II. Its tone remoted. It is setup and working, but I'd like to know how to set the tone remote -- Ham Radio Spoken Here.NU5D Nickel Under Five Dollars
[Repeater-Builder] Service monitor
I currently have at work, an Motorola R2600 service monitor. I need to upgrade to one that will work with Motorola VRM's like the VRM600 and 850's using the RDLAP, or whatever it is... Anyway, I would assume I would go with the next service monitor up that has the stuff I need. I know they are made by someone else now. But are there any other monitors I should be looking at? Thanks for the input. -Tim theVAP.com 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] Ultimate test coax cables
Thanks Eric for the nice detailed message. Gives me a good place to begin. -Tim www.ldservice.com/tim/tim Eric Lemmon [EMAIL PROTECTED] wrote: __ Tim, My preference is a matched pair of coaxial cables, 1 meter long, made with RG-400/U (not RG-142/U!) double-shielded cable. Each end to have crimped, silver-plated (not nickel-plated) N male connectors with gold-plated center pins and Teflon dielectric. The crimp ferrules shall be reinforced with two nested layers of adhesive-coated shrink tubing for strain and flex relief. When carefully constructed and characterized with a network analyzer, these cables ensure that duplexer, isolator, cavity, and filter tuning can be accurate and repeatable. The double shielding ensures that any duplexer or cavity tuning done at a repeater site is not going to suffer interference from a high-RF environment. The use of premium-quality crimped connectors ensures that impedances are constant. Of course, EP-10 plastic dust plugs are inserted into the connectors during storage, to maintain cleanliness. 73, Eric Lemmon WB6FLY [EMAIL PROTECTED] wrote: I want to build the ultimate set of test cables for working with repeaters and tuning duplexers. What are your recommendations? -- -Tim --- YAHOO! GROUPS LINKS + Visit your group Repeater-Builder on the web. + To unsubscribe from this group, send an email to: [EMAIL PROTECTED] + Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. --- Yahoo! Groups Links 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] Ultimate test coax cables
Your overkill may have saved me a couple of hours today. When I was working with my repeater I thought I had a big loss through the duplexer. It turned out it was my substandard cables. Then it was a bigger bear trying to tune it back after I messed with it. I'm not sure what kind of cables I have but they are the off brown color with double sheilding and silver braid. But the gauge must be the culprit because its as small or smaller than 58. Tim .Is this overkill? Perhaps. But, just one extra trip to a site to fix a substandard cable installation is far more costly than the extra money a first-class cable job adds. 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] motorola moxys
Go for it. I built my first repeater using moxys. It worked well and sounded good. It's a great learning experience. Get in there and tinker around and figure stuff out. That's what ameatur radio is all about. -Tim kb9qbt wrote: To the group, This is my first post but have been a member for a while. I managed to get a hold of couple of motorola moxys uhf I think. Is it possiable to convert them to 440 and using both set them up as a repeater. I know I would need some type of controller, this my first venture into repeater setup so my question to the group. Is this a worthwhile endeavor or will I be spinning my wheels? Thanks in advance for your help. Dan kb9qbt Yahoo! Groups Links Yahoo! Groups Links 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] OT:Interferrence Help
This is a little off topic but I could use some help. I am working on a fire truck that is getting interferrence on the VHF (156.075mhz) from the trucks wiring. If I put an HT near I get the interferrence on the HT. When I disconnect the battery it goes away. We removed one fuse at a time and it went away when we pulled the fuse to the trucks computer ECM module. We tried an ECM module from another truck w/o the interference problem and we still had it in the bad truck. Next I tried sniffing around with a spectrum analyzer and found the highest noise near a large bundle of vehicle wiring. We are talking a tightly bunched 2-3 inch bundle. Tried adjusting the squelch to open at .5uV but that did not help. Need some idea on how to proceed. Thanks Tim 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] Please contact!
I replied direct about the TM-7VA and got no response either. : . www.ldservice.com/tim/tim Dave [EMAIL PROTECTED] wrote: __ I emailed him off list wanting the 742 but he's never replied Doug Strobel-kb3ham [EMAIL PROTECTED] wrote: rus if i were you i would email nick off the list as maby he is not reading all the stuff that is being posted 73 de kb3ham -Original Message- From: russ [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 08, 2005 5:36 PM To: [EMAIL PROTECTED] Cc: Repeater-Builder@yahoogroups.com; bill price Subject: [Repeater-Builder] Please contact! Hello Nick, I am sending this for Bill Price, KC2JGL who is trying to contact you. He wants to possibly buy your Comm-3 and (or) Kenwood TM-742 mobile. His contact info is. Bill Price: Phone, 609-820-4699 e-mail, [EMAIL PROTECTED] ham call, KC2JGL Please contact bill as soon as you can direct please. Sincerely, Russ Stafford, EE,PE. GROL, PG-GB-01751. HAM, W3CH. GMRS, WPYK-254. --- message truncated --- 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] Repair list?
Is there a radio repair list like this one is for repeaters? A lot of radios have the same kind of breakdowns over and over again, so it would be nice to have a list to discuss them. Just wondering. -Tim 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] Duplexer story update
Thanks to all the help here and repeater-builder.com I got it figured out. Quite interesting actually. I verified the input to the duplexer had 42 watts by using a coupler on the duplexer input cable and hooking it up to my service monitor. And hooked it all back up and I had 42 watts into the service monitor measuring the duplexer output. So 42 watts in and 22 watts out was -2.8 db loss. Next I checked the antenna reflected power with a bird. Bare with me here because the bird readings are vastly different then my recently calibrated monitor. The ant showed 38 out and 1/2 watt back with the bird. Pretty good. So I checked the input to the duplexer. 65 watts out 12 back. Not good. (I guess) I say I guess here because changing the length of the duplexer input cable seems to affect it. I decided to check the duplexer tuning once again and pulled the unit. Retuned the plungers all the way up and down and could not find a better peak. Reset the notches and reinstalled. Same kind of readings as before. Then I tried a new cable from the TX to the duplexer input that I had. It just happened to be about 3 inches longer than the original. That gave me on the bird 65 out and 1 back on the antenna. The service monitor showed 32.5 watts out of the duplexer. Reverified the 42w into the duplexer on the new cable. For a total insertion loss of -1.1 db. Also rechecked the densense and could not measure any. Now for a homework assignment. The original *bad* cable is 24 inches long. And the TX freq is 483.0875Mhz. So what wavelength would that be that caused the problem. And I assume it is the original cable when the repeater was installed 25+ years ago. Was it always wrong or did it not effect the original duplexer the same?... Thanks again! -Tim 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] Duplexer story update
Sorry Glenn. Don't have that info. I vaguely remember R9P or something. -Tim www.ldservice.com/tim/tim -Original Message- From: Glenn Little WB4UIV [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 5:18 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplexer story update In order to do a meaningful calculation, I would have to know the type of dielectric in the coax to determine the velocity factor. The VF will be less than one. 73 Glenn WB4UIV At 07:36 PM 10/01/04, Tim S. wrote: Thanks to all the help here and repeater-builder.com I got it figured out. Quite interesting actually. I verified the input to the duplexer had 42 watts by using a coupler on the duplexer input cable and hooking it up to my service monitor. And hooked it all back up and I had 42 watts into the service monitor measuring the duplexer output. So 42 watts in and 22 watts out was -2.8 db loss. Next I checked the antenna reflected power with a bird. Bare with me here because the bird readings are vastly different then my recently calibrated monitor. The ant showed 38 out and 1/2 watt back with the bird. Pretty good. So I checked the input to the duplexer. 65 watts out 12 back. Not good. (I guess) I say I guess here because changing the length of the duplexer input cable seems to affect it. I decided to check the duplexer tuning once again and pulled the unit. Retuned the plungers all the way up and down and could not find a better peak. Reset the notches and reinstalled. Same kind of readings as before. Then I tried a new cable from the TX to the duplexer input that I had. It just happened to be about 3 inches longer than the original. That gave me on the bird 65 out and 1 back on the antenna. The service monitor showed 32.5 watts out of the duplexer. Reverified the 42w into the duplexer on the new cable. For a total insertion loss of -1.1 db. Also rechecked the densense and could not measure any. Now for a homework assignment. The original *bad* cable is 24 inches long. And the TX freq is 483.0875Mhz. So what wavelength would that be that caused the problem. And I assume it is the original cable when the repeater was installed 25+ years ago. Was it always wrong or did it not effect the original duplexer the same?... Thanks again! -Tim Yahoo! Groups Links Yahoo! Groups Links 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] Duplexer story update
That is interesting that both you and Coy mentioned the z-matcher. I have never heard of one. I will be looking into it for the sake of knowledge enrichment ;-) I assumed that the input cable length from the pa to the duplexer did not matter and that I hit some kind of magic wavelength length that botched it up. Adding the three inch longer cable fixed/changed it. Since I now measure -1.1db through the duplexer I'm happy that I got it all matched right. I'd feel sorry for a guy trying to figure this out without a tracking generator to tune the duplexer. That made me feel confident enough that the problem was somewhere else. I considered retuning the duplexer under power to peek it, but decided against it. That would have worked around the problem or made things worse. It was a very interesting learning process this week that started with desense and ended with a new duplexer and TX cable. At the start was 15 watts out of the duplexer with 15db desense. Now its 32 watts out and 0 desense. Think they will notice the difference? ;-) -Tim -Original Message- From: Eric Lemmon [mailto:[EMAIL PROTECTED] Sent: Friday, October 01, 2004 6:55 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplexer story update Tim, Your experience is a reminder that repeater construction is not an exact science! The fact that the power through the duplexer changed radically when the jumper cable length was changed is evidence that your power amplifier was not correctly matched to your duplexer. Although the length of the cable is certainly a factor, you should also check to be certain that the cable is not defective. If you have several hours of free time, and nothing else to do, you can use the cut and try method of finding the magic length of cable that transforms the output impedance of your PA to the input impedance of your duplexer. Simply fabricate a number of jumper cables that are cut to length at 1/2 inch intervals, and try each one until the forward power is at a peak. Some proponents of this method prefer to start with a cable that is a foot or so too long, and then cut off 1/2 inch at a time, reattach the connector, and retest until the optimum length is found. It is difficult to establish the exact length a PA to TX cavity jumper must be, even if the velocity factor of the cable is known, because its length also depends upon the length of the coupling loop inside the cavity- and the loop length may be an unknown. If you don't have a lot of idle time to play this game, you can purchase an impedance matcher (Z-Matcher) for about $90 that will allow you to perfectly match your PA in about 30 seconds. These nifty devices are made by Telewave, Sinclair, and others. They are nothing more than a pi network inside a box, tuned with two variable capacitors. You could also build one of these devices for much less money, but then you would be spending a lot of time building something that is supposed to save you a lot of time. It is possible that a ferrite isolator between your PA and the TX cavity input will improve your power throughput, but that device should be employed for PA and IM protection more than PA matching. YMMV... 73, Eric Lemmon WB6FLY 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] Duplexer story update
-Original Message- From: Thomas Oliver [mailto:[EMAIL PROTECTED] I like to tune the duplexer with service monitor for best peak and notch like you did then hook up repeater and check reflected power at transmitter output as you did and compare foreward and reflected readings with duplexer inline and out of line. I compared the two as well even after the cable *fix*. I don't know if I would rely on that method though. It seemed to be higher swr when I checked it between the TX and the duplexer. I think it's one of those cable weird nesses. I like the idea of reading the loss through it. If reflected power is more with duplexer inline then most likely there is an impedance mismatch between the duplexer input and the transmitter output. If the difference in reflected power is small with duplexer in/out, I just tweak the first pass adjustment (tx off) for minimum reflected and usually can get a good match equal to reading with duplexer out of line. When you do this, do you go back and adjust the notch? If the difference is great like you described then i try a different jumper a little shorter or longer. That is something I would not have thought of if not for this list and repeater-builder.com. Ain't the internet neat. Wacom had a procedure for finding the right length jumper it was to add right angle conectors or jumpers increasing in length an inch at a time (two inches at a time on two meters) until you have added 1/2 wave total and the lowest reflected reading was obtained then make a new jumper with the new optimized length. Nice technique. I got lucky and had a cable already made up that was just a few inches longer. You could have had a bad cable or it may just cut to a length that made the transmitter mad. I think it was the length. Will never know as I don't plan on putting that cable back in service! If your tx output and duplexer input were 50 ohms then any length 50 ohm cable would work. But in the real world if your service monitor is not exactly 50 ohm and transmitter output and duplexer input is not exactly 50 ohm Changing length of the jumper will improve preformance as you described because your jumper is acting like a transformer. Weird stuff. Trial and error seems to work best. Thanks for the input! -Tim 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] Duplexer story update
So from what I am getting here. Only some PA's are affected by the cable length. Mine happens to be a Master II Tband. It's only trial and error to discover it the problem. It's trial and error to make the cable length right so the PA is happy. If I understand this right, what cause the problem is the PA's output is not a true 50 ohms by failure or design. This causes the 50 ohm coax to not be matched to transfer the power from the PA to the duplexer. So you alter the cable length to make it match the output of the PA impedance. Which in turn helps it to transfer the power to the duplexer. Why does this work? Isn't the input to the duplexer also 50 ohms? Too much thinking for a Saturday morning! -Tim -Original Message- From: Joe [mailto:[EMAIL PROTECTED] Sent: Saturday, October 02, 2004 4:45 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplexer story update I have used a short cable, then used various coax adapters to lengthen the cable. This is easier than the cut and try technique. I have one of those adapter kits that allows you to put together any combination of adapters. For example, I can make a male UHF to female UHF adapter. This will add length to the cable easily and quickly. If I see that cable length is effecting matching, I then take the time to cut a cable to that magic length. Joe If you have several hours of free time, and nothing else to do, you can use the cut and try method of finding the magic length of cable that transforms the output impedance of your PA to the input impedance of your duplexer. 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] Duplexer story update
. Although the length of the cable is certainly a factor, you should also check to be certain that the cable is not defective. What would be the best way to check the cable for not being defective? I checked the output directly off the PA and then through the cable and it was the same. The cable was visually inspected and looked fine. -Tim 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] Duplexer story update
Wow, thanks Fred and Kevin. That sums it up quite well for me. I'm one of those guys who needs to know why its fixed even after its fixed! I appreciate the detailed explanations. -Tim -Original Message- From: Kevin Custer [mailto:[EMAIL PROTECTED] Sent: Saturday, October 02, 2004 10:07 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplexer story update Tim S. wrote: So from what I am getting here. Only some PA's are affected by the cable length. Mine happens to be a Master II Tband. It's only trial and error to discover it the problem. It's trial and error to make the cable length right so the PA is happy. Right. Wacom pointed this out in this document: http://www.repeater-builder.com/wacom/wp6xxVHFtuninginstructions.pdf Look o page 4 Many of us choose to use commercial equipment converted to the ham band. While this equipment *may* have presented a 50 ohm load or source at its design frequency, it may not when moved to another portion of the spectrum. Even equipment designed to work, and operated on a particular band *may* not present a 50 ohm load. Motorola realized when designing that vintage of PA's for the UHF Micor that things could easily go wrong; and is why every Micor UHF Station and Mobile came with a circulator. GE eventually adapted to it as well; in their UHF stations: http://www.repeater-builder.com/ge/mastrIIuhfpacomments.html If I understand this right, what cause the problem is the PA's output is not a true 50 ohms by failure or design. This causes the 50 ohm coax to not be matched to transfer the power from the PA to the duplexer. Right, failure not necessarily by design, may be a better way to put it. So you alter the cable length to make it match the output of the PA impedance. Which in turn helps it to transfer the power to the duplexer. Why does this work? Isn't the input to the duplexer also 50 ohms? The transmitter output *may* not be 50 ohms. The duplexer *may* not be presenting a stable load to the transmitter due to the fact that the load is reactive and not consistent over a wide frequency range. The duplexer may not be looking at a perfect 50 ohm antenna over its operating range. With all of the variables, it would be difficult to impossible to predict 'perfect' cable lengths between the duplexer and radio set, that's why using a matcher or experimenting with lengths is likely quicker. Kevin Custer 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] The duplexer story...
As I stated a few times here I have a duplexer that has been giving me desense. To get rid of the desense I turned down the TX power until it went away because the duplexer is rusty and hasn't been messed with in 20+ years. I came across another duplexer in a base station cabinet we had and pulled the duplexer out. Here are the specs of it: TPRD-14744 (470-512 MHz) Type: 4 cavity pass-reject Minimum freq. spacing 3 MHz Insertion loss 1.0 dB Max. continuous power 250 watts TX noise supp. at Rx freq. 90 dB Rx isolation at TX freq. 90 dB Temperature range -30 to +70C I used the tracking generator and tuned and notched it on frequency. My plan was to use this duplexer as a backup if the original one would not tune. When I checked desense on the original again it was around 10db. I pulled the duplexer and found the reject was only about -75db on both sides. I adjusted the notches and got it down under -90db but noticed it jumped around -95db then -90db, etc... I did use double shielded cables for tuning. I checked the passes and they seemed ok, so I did not touch them. Put it back in place and turned the power back up from 15 watts out of the PA to 42 watts out of the PA. The desense jumped big time to around 20db. So I pulled the old duplexer and put in the spare. Now I have no measurable desense. So that's a plus. However, I put the service monitor on the PA output and read 42 watts. Hooked the cabling up to the duplexer and then checked the output of the duplexer and only read 22 watts. That's like a -2.8db loss. I didn't think at the time to check the interconnect cable from the PA to the duplexer, but I can't imagine that having a -1.8db loss. Since the duplexer should only have -1.0 db insertion loss. When I tuned the replacement I double checked all the peaks locked them down then did the rejects. So I am pretty confident the duplexer is set right. So, in the end the repeater went from 15 watts out of the duplexer with 10db desense to 22 watts out with no desense. 1. Can something in the original duplexer go bad internally to cause the desense? Or must my tuning be suspect? 2. Think I need to worry about the -2.8 db power loss? All I can think of doing is checking the interconnect cable from the PA to the duplexer input. Another note: When I retuned the base station duplexer, I kept the low side low and the high side high, meaning I am now transmitting on what was originally the RX port since it went from a base station use to repeater. Could this be a problem if I really have -2.8db insertion loss? -Tim 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] The duplexer story...
Comments within... -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Tim, a couple of questions come to mind. 1.) Are you trying to tune a T-band Duplexer down to 440? Not reccomended. No I am not trying to make it go to ham band. I maintain a private tband repeater. 2.) Are you running a circulator between the duplexer and the antenna? It would between the TX and the duplexer, but I know what you meant. And I am not running one. 3.) Are you using the same cables out of the repeater to connect to the duplexer (either one) and seeing a change? Not sure what you mean here. I took my test cable from the output of the transmitter and measured 42 watts. Then I hooked the cable from the transmitter to the duplexer input. Next I took my measurement from the duplexer antenna port. So, if your asking did I take a measurement through the cable from the pa to the duplexer no. I should have. Thanks for the input Barry. -Tim 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] The duplexer story...
-Original Message- From: Paul Kelley [mailto:[EMAIL PROTECTED] What is the SWR looking into the duplexer? Did not check that. What should it be? I assume 10% or less reflected. Have you tried different length cables from the transmitter to the duplexer and looked to see if the power coming out of the duplexer changes? Nope, but that's next on my list. I would investigate to find out why you're seeing these numbers. If you're really losing 2.8 dB in the duplexer, something isn't right. Try some different cable lengths between transmitter and duplexer to see if it has an effect. I plan on checking out some more. I am going to put a barrel connector on the end of the PA coax and measure just before it goes into the duplexer then measure the output of the duplexer. If that still seems funky I will try a different length cable. But... what if the duplexer does have the -2.8 loss, then I guess retuning is in order? I read on the repeater builder site that some people tune with the TX power at the site. That seems a bit risky to me and it would drastically change the notches. Let us know what you find. Will do! Thanks Paul. -Tim 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] The duplexer story...
Thanks Joe. I'll check that out. -Tim -Original Message- From: mch [mailto:[EMAIL PROTECTED] Sent: Thursday, September 30, 2004 10:44 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] The duplexer story... Tim S. wrote: -Original Message- From: Paul Kelley [mailto:[EMAIL PROTECTED] What is the SWR looking into the duplexer? Did not check that. What should it be? I assume 10% or less reflected. 4% is 1.5:1 (100W out - 4W back OR 50W out - 2W back) It should be no more at the TX end of the duplexer than at the antenna end of the duplexer. If it is higher, look for a spurious TX. That might also explain your original desense as well as the additional power out. Joe M. 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] Best way to adjust dev?
Thanks Jim. Great explanation. -Tim -Original Message- From: Jim B. [mailto:[EMAIL PROTECTED] Leave the tone turned off first. If you have any way to put a local mic on the tx, or generate audio DIRECTLY into the mic input, set the deviation on the transmitter for maximum deviation, usually +/-5Khz (For ham rptrs, I set it up to abt 5.5 to keep folks from going into limiting normally. Ideally, a normal user with reasonable audio should not go into limiting very often.) Then go back and generate 1Khz @ +/-3Khz deviation, and set the repeat level for 3 in, 3 out.. It helps at this point to do a audio sweep and plot in/out deviation across the audio spectrum. Then, with no other mod, set the PL for +/-600-800 hz. -- Jim Barbour WD8CHL 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] Best way to adjust dev?
What's the best way to adjust the transmit deviation for a repeater. I was thinking of doing it this way. Setup the service monitor for duplex mode and hook the cable up to the antenna port on the duplexer. Manually key the transmitter and adjust the PL for .6 kHz deviation. Then adjust the generator for a 1k tone at kHz deviation with a PL tone at 6khz deviation. Then watching it on the duplex monitor adjust for 3.6 kHz (with .6 being the TX pl) on the transmitter. -Tim 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] detuned duplexer cause intermod?
Thanks for the information Eric. Really clears things up well. -Tim www.ldservice.com/tim/tim -Original Message- From: Eric Lemmon [mailto:[EMAIL PROTECTED] Sent: Monday, September 20, 2004 6:39 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] detuned duplexer cause intermod? Tim, You are to be commended for thinking about possible interference to others; I wish all repeater owners were so conscientious! Even if the duplexer was perfectly tuned on a network analyzer, the PA may become unstable when the power is lowered below a certain point. This instability usually causes spurious emissions which definitely WILL cause interference to other stations. This is not the same as intermod. 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 Radio programming
Mike, I used to get mine done here: Silverado Avionics (707) 255-5588 2500 Airport Rd Napa, CA 94558 -Tim www.ldservice.com/tim/tim -Original Message- From: Mike Perryman [mailto:[EMAIL PROTECTED] Sent: Tuesday, September 21, 2004 8:34 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Midland Radio programming Does anyone know where I can get a Midland 70-342b programmed? I need to locate a 70-1000 or 70-1000c programmer. Not having much luck with google-fishing.. Thanks, 73's Mike Perryman www.qsl.net/k5jmp 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] detuned duplexer cause intermod?
Pretty sure I know the answer to this. But can a transmitter keying into a duplexer that's detuned cause intermod interference? I have a transmitter that I turned down the power because it had desense on it. Turning the power down fixed the desense but now I am wondering since its still transmitting into a poor load, can't that cause some intermod interference to other repeaters? It's a tband repeater. Can that cause problems all the way to vhf? I haven't tried retuning the duplexer because one, it has not been touched in 20 years and two, the shafts are rusty. We are currently planning on replacing the repeater but it could take up to another year and I don't want to cause interference to anyone during that time. -Tim 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: detuned duplexer cause intermod?
Thanks for the info. I may have another duplexer in an older repeater that I could check out first. It would be nice to have a backup standing by if the original craps out during the retuning. -Tim -Original Message- From: skipp025 [mailto:[EMAIL PROTECTED] Sent: Monday, September 20, 2004 8:14 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: detuned duplexer cause intermod? Tim S. [EMAIL PROTECTED] wrote: Pretty sure I know the answer to this. But can a transmitter keying into a duplexer that's detuned cause intermod interference? big time interference. I have a transmitter that I turned down the power because it had desense on it. The transmitter wouldn't have desense, but it would and can be the source of... Turning the power down fixed the desense but now I am wondering since its still transmitting into a poor load, You need a circulator/isolator panel to deal with the reflected power. ...can't that cause some intermod interference to other repeaters? Yes It's a tband repeater. Can that cause problems all the way to vhf? Yes I haven't tried retuning the duplexer because one, it has not been touched in 20 years and two, the shafts are rusty. Clean them off with a brass or stainless steel brush. Don't use plain steel brushes. Lightly lube the cleaned shafts with a synthetic spray like Amsoil MP Spray or Dupont Teflon. Use a small drill motor to run the shafts in and out at least 75% of their normal travel. Then retune them to the desired operating frequencies. The hope is that running the shafts in and out might remove any basic oxidation on the internal plunger and the internal finger-stock will sort of polish-off or clean any pitting on the tunning plunger. We are currently planning on replacing the repeater but it could take up to another year and I don't want to cause interference to anyone during that time. -Tim Possibly too late already. cheers skipp skipp025 at yahoo.com www.radiowrench.com Yahoo! Groups Links 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: detuned duplexer cause intermod?
Will do! Thanks for the input. -Tim www.ldservice.com/tim/tim -Original Message- From: Tony lelieveld [mailto:[EMAIL PROTECTED] Sent: Monday, September 20, 2004 2:51 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: detuned duplexer cause intermod? Tim S. [EMAIL PROTECTED] wrote: Pretty sure I know the answer to this. But can a transmitter keying into a duplexer that's detuned cause intermod interference? It sure can. A local area repeater in Michigan on 146.64/04 was causing interference, and was being heard, on a 146.68/08 repeater about 60 miles away. Someone, un-authorized, had made adjustments to the duplexer (Tx out into duplexer 40 W, power out of duplexer 3 Watt). The picture on the spectrum analyzer looked like a Christmas tree as the PA was going into all kinds of spurious oscillations. After retuning with proper equipment (vector network analyzer) all interference stopped and the TX was clean again. An isolator will do the trick to protect the PA and reduce the chance of spurious oscillation and inter-modulation but it will not cure the problem. Retune the duplexer ASAP with proper equipment. 73, Tony VE3DWI --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.742 / Virus Database: 495 - Release Date: 19/08/2004 Yahoo! Groups Links 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/
