Re: [Repeater-Builder] Portable Repeater - A Case History
At 1/2/2005 09:03 PM, you wrote: Kevin, Yes, it is asymmetrical. Each of the three high-pass resonators has two black plastic plugs near the connector end, while the low-pass resonators each have one plastic plug. A Celwave engineer told me that the 5085-1 is manufactured to order, and that the coupling loops are factory-adjusted through these ports for optimum return loss at a particular split, and for a certain band segment. As a result, the 5085-1 is not really tunable over the entire high VHF band. I don't see that as a negative, since it was ordered specifically for this portable repeater application and is not likely to require retuning. 73, Eric Lemmon WB6FLY I'll have to take a closer look at mine (this is the one that I bought Kevin swept at Dayton '03). Turns out it's asymmetrical as well (84 dB notch on high freq., 69 dB on low). Loss is higher on the low side as well (1.8 vs. 1.1 dB), so tighter coupling on the low pass/high notch side makes sense. No need to make any changes for my application, though, since TX happens to be the low freq. And no that had nothing to do with which freq. was picked to be TX for the portapeater pair in the SoCal 2M bandplan! 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 Repeater - A Case History
Kevin, Yes, it is asymmetrical. Each of the three high-pass resonators has two black plastic plugs near the connector end, while the low-pass resonators each have one plastic plug. A Celwave engineer told me that the 5085-1 is manufactured to order, and that the coupling loops are factory-adjusted through these ports for optimum return loss at a particular split, and for a certain band segment. As a result, the 5085-1 is not really tunable over the entire high VHF band. I don't see that as a negative, since it was ordered specifically for this portable repeater application and is not likely to require retuning. 73, Eric Lemmon WB6FLY Kevin Custer wrote: Eric Lemmon wrote: It comprises six helical resonators in a notch-only configuration. Its insertion loss at RX is 1.1 dB, and at TX is 1.4 dB. The notch depth at RX is 92.5 dB and at TX is 79.4 dB. These are very good numbers, better than what is needed for zero desense in this application, and are roughly equivalent to four 8 inch standard cavities at a 600 kHz split. Is it asymmetrical in design or what is the reason for the differing numbers between the two sides? At least the notch of the transmitter side-band noise is the big number. Kevin 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 Repeater - A Case History
Eric Lemmon wrote: It comprises six helical resonators in a notch-only configuration. Its insertion loss at RX is 1.1 dB, and at TX is 1.4 dB. The notch depth at RX is 92.5 dB and at TX is 79.4 dB. These are very good numbers, better than what is needed for zero desense in this application, and are roughly equivalent to four 8 inch standard cavities at a 600 kHz split. Is it asymmetrical in design or what is the reason for the differing numbers between the two sides? At least the notch of the transmitter side-band noise is the big number. Kevin 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] Portable Repeater - A Case History
I recently built a portable 2m repeater that is about the size of a bowling bag and weighs about the same. It is built into an SKB carrying case that is rugged, dripproof, and good-looking. The secret of getting a full-duplex radio and the duplexer into a box measuring about one cubic foot in volume is choosing the right components and using a widespread pair. As a resident of Central California, my area is under the jurisdiction of the Two-Meter Area Spectrum Management Association, otherwise known as TASMA. This coordinating body wisely authorized a widespread frequency pair, exclusively for portable repeater application, to be used only for temporary and emergency situations. The frequencies are 147.585 MHz input and 144.930 MHz output. This is a split of 2.655 MHz, which is just within the capability of a compact base station duplexer. I chose an RFS/Celwave 5085-1 duplexer, which works perfectly in this application. The 5085-1 duplexer is about 8.5 inches wide, 12 inches long, and just under 2 inches thick- about 30% larger in all dimensions than the common notch-type mobile duplexer. It comprises six helical resonators in a notch-only configuration. Its insertion loss at RX is 1.1 dB, and at TX is 1.4 dB. The notch depth at RX is 92.5 dB and at TX is 79.4 dB. These are very good numbers, better than what is needed for zero desense in this application, and are roughly equivalent to four 8 inch standard cavities at a 600 kHz split. The transceiver is a Motorola R1225, a programmable full-duplex radio that includes both TPL and DPL capability, a built-in repeater controller, polite Morse ID, courtesy beep, PA protection, etc. This radio is what is inside a GR1225 repeater, and is available in either a 1-10 watt or a 25-50 watt model for VHF, and in 1-10 watt and 25-45 watt versions for UHF. All versions will program into the Amateur bands without modification. I am using the 10 watt model, since my ARES group will use this repeater primarily for communication within a relatively short radius. The model number is M03GRC90C2AA. With a 5 MHz split at either VHF or UHF, a similar portable repeater could probably use a common mobile duplexer. 73, Eric Lemmon WB6FLY Dakota Summerhawk wrote: Is the best way to have a mobile repeater up and running with two mobile radios and a duplexer? Looking for a way to be able to run a couple of repeaters, one VHF and one UHF, for a mobile communications van. Can anyone recommend ways to cut down on weight and space? 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/
