The repeater transceiver is a NEUTEC commercial radio in the 220 band. The repeater is a RANGER brand unit with the NEUTEC unit as the heart. ( RANGER is out in Calif from what I remember..they make a line of 10m. 6mtr and 11 mtr radios ). The cabling in the rack is all double shielded RG-214 .every bit. All the appliances came with UHF connectors, so I had not option to cable with N type connectors which I would have preferred. Connectors are silver. I am using an ARCOM 210 controller. Power supply is a rack mount ASTRON 35. I had planned on a larger supply or to use a separate supply on the amp, but the draw against the one supply with all the components should not be taxing it. The transmitter was dialed back to about 10 watts and is driving a TE Systems amp doing about 100 watts to the duplexer. This power level was not a problem the night before the visit to the Motorola shop, but we could detect some desense and I was hoping to improve the situation. The antenna is a HyGain V-3 ( this is a temporary antenna that was available for the testing phase ) ground plane which has 2 sets of radials. The antenna is fed with ½ Heliax. The antenna is 30 to 40 feet horizontially separated and 20 ft vertically. ( Not a lot of separation to be sure but again the install at this location is temporary while working the kinks out..). Thats the basic rundown -M
From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Thomas Oliver Sent: Wednesday, July 30, 2008 12:41 AM To: [email protected] Subject: RE: [Repeater-Builder] Curious Situation Welcome to the wonderful world of duplexers. When I first started messing with repeaters I used nothing more than a signal generator with attenuator and an ht with a bar graph signal strength meter. That and a dummy load is the minimum you really need to do a decent job. I replaced a 2 meter receiver with a hotter receiver one time and experienced reduced rx coverage much as you described, I traced it down to the cable between the transmitter and duplexer. This was causing the transmitter to see some reflected power looking into the duplexer. As per Wacom manual I started adding a couple inches at a time until the reflected power went away. I ended up having to add about six inches to what I had. The hamtronics receiver wasn't bothered by the resulting effects from the mismatched transmitter load but the Spectrum was. My duplexers were tuned at the factory I suppose on a network analyzer that is supposed result in a perfect 50 ohm input, trouble is my transmitter was not a perfect match hence the reflected power. By adding length to the cable I was making a transformer that made the receiver happy. This may not have anything to do with your problem at all. You need to check your antenna match first then see if your transmitter is seeing the same SWR when the duplexer is in line it should be the same. You need a way of quickly turning the transmitter on and off while listening to a weak signal. If the signal improves when the transmitter is off then you are experiencing de-sense. This could be caused by many things. Bad cables or connectors or feed line or duplexer or too much power or spurious transmitter or poor receiver or... the list goes on. you need to give us a rundown on what your system consists of - what antenna feed line connectors cables transmitter and receiver are you using. tom ----- Original Message ----- From: Michael Ryan <mailto:[EMAIL PROTECTED]> To: [email protected] Sent: 7/29/2008 11:36:32 PM Subject: [Repeater-Builder] Curious Situation Rbers, I posted a note very early this week about my looking for a someplace to get a 220 duplexer tuned in the TAMPA area. Having not much luck I contacted a local MOTOROLA shop and paid $95 for the service. The receipt returned with the cans indicates that the specifications published by WACOM are very close. Having tuned these merely to incoming signals before, peaking them while the repeater is still in a testing mode, seemed to return decent results but the tune-up was thought to be a better idea. Not so . Todays tune-up hardly was worth the wait or the price based on the results. While a 5 watt HT 10 miles away could work the repeater, now 25 watts from a roof top antenna is now just about full quieting. Fifteen watts does not make the repeater through the same roof top ground plane. Does logic dictate that we go back to seat of the pants tuning and cast fate to the wind? - Mike No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.5.6/1579 - Release Date: 7/29/2008 6:43 AM __________ NOD32 3301 (20080727) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com
