Re: [Repeater-Builder] Duplexer Wanted

[Teton Amateur Radio Repeater Association (TARRA)]

Hello Randy, With only 25 watts, the other option is to use two antennas with some separation. And it is also helpful to add a filter to the transmit line and another to the receiver. At least add one to the transmit side. Adding a filter to the transmit side would help eliminate the high power interference, and no loss for the receiver. And of course PL on your receiver would help too. I've been running a 35 watt repeater with two antennas and a transmit filter for more than a year and it works just fine. Mick - W7CAT Be sure to check out all the latest at http://www.wyocat.com/tarra Randy wrote: Hi Eric and others, Thanks for the info. We are wanting something portable but not as to carry them around. Just something we can transport with out to much trouble, The repeater puts out about 25 watts. I guess thats why most use UHF gear for this. Randy ----- Original Message ----- From: "Eric Lemmon" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Saturday, April 22, 2006 12:34 PM Subject: RE: [Repeater-Builder] Duplexer Wanted Randy, You won't find such a duplexer for a 600 kHz split. Mobile duplexers are notch-only, with no bandpass action at all. As such, they are almost useless for anything below a 5 MHz split. Even the larger "compact base station duplexers" such as the Celwave 5085 series are generally no good below a 3 MHz split. One of my local ARES groups has a "portable" 2m repeater that uses a Telewave TPRD-1454, 4-cavity Bp/Br duplexer that works fine with the low-power Hamtronics repeater. It's built into a foot-locker sort of wooden box that can be carried by two men- more like transportable than portable. My CommShop program calls for about 77 dB of isolation between a 5 watt transmitter and a 0.35 uV receiver at a 600 kHz split, and this is exactly the specification of the TPRD-1454 duplexer. For 10 watts TX power, you'll need about 80 dB of isolation. At 2m, a very small duplexer is simply not practical. The 2m coordination group in my area of California, TASMA, wisely set aside one wide-spaced frequency pair for short-term portable repeater usage. This pair is 147.585 MHz input and 144.930 MHz output, for a split of 2.655 MHz. This is within the capability of a Celwave 5085-1 compact base station duplexer, when ordered tuned on this pair from the factory. I am assembling a portable repeater using this duplexer and a Motorola R1225 10-watt full-duplex radio. The entire repeater fits into a case that is less than one cubic foot in volume and can be carried with one hand. The Celwave 5085 duplexer is about 50% larger than a typical mobile duplexer, and it comes in models for both 3 MHz and 5 MHz splits. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com] On Behalf Of Randy Sent: Saturday, April 22, 2006 8:12 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Duplexer Wanted We are looking for a Mobile type duplexer for a portable Repeater. tuned to 147.015 tx and 147.615 rx. If anyone has one or knows where we can get one please let me know, Thanks Randy 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/ __________ NOD32 1.1501 (20060421) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com 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.