[Repeater-Builder] Transmitter Combiner
Is there a cheap way to combine two txcvrs into one antenna... 144.39 APRS and 145.550 packet?
RE: [Repeater-Builder] Transmitter Combiner
You could try a duplexer? There's enough channel separation it should work OK. Not sure what duplexer would be best for running duplex though each side but I'm sure there out there. 73 Ross kc7rjk -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of na4it Sent: Thursday, July 15, 2010 1:04 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Transmitter Combiner Is there a cheap way to combine two txcvrs into one antenna... 144.39 APRS and 145.550 packet?
Re: [Repeater-Builder] Transmitter Combiner
About the only way is via a duplexer. (Cheap? Well... used??? ;- ) Joe M. na4it wrote: Is there a cheap way to combine two txcvrs into one antenna... 144.39 APRS and 145.550 packet?
Re: [Repeater-Builder] Transmitter Combiner
Maybe a pair of those 6 cavity mobile duplexers with the 5 MHz split can be configured as 6 notch sections each to reject the opposite frequency. and then combine them with a T to the antenna. Lossy, but should be cheap, I've seen those go in the $20 range. On Thu, Jul 15, 2010 at 1:49 PM, MCH m...@nb.net wrote: About the only way is via a duplexer. (Cheap? Well... used??? ;- ) Joe M. na4it wrote: Is there a cheap way to combine two txcvrs into one antenna... 144.39 APRS and 145.550 packet? Yahoo! Groups Links
Re: [Repeater-Builder] Transmitter Combiner
At 7/15/2010 13:53, you wrote: Maybe a pair of those 6 cavity mobile duplexers with the 5 MHz split can be configured as 6 notch sections each to reject the opposite frequency. and then combine them with a T to the antenna. Even though they're notch duplexers, each side has a very weak pass response, just enough so that you can't use the low pass side as a high pass. As a result, trying to use one as a 6-section notch filter by putting all the notches on the same frequency using the TX RX ports as input output won't work, as it would have several dB of loss @ 5 MHz offset, even more @ ~1.2 MHz. Another alternative to a full size 2 meter duplexer would be a dual isolator following by a pass cavity on each TX, then T the cans together using the correct phase-critical lengths of coax. Might be cheaper if you happen to have an inexpensive source for 4 VHF isolators. Bob NO6B
Re: [Repeater-Builder] Transmitter Combiner
I could live with 3dB of loss which is about what I would expect per leg. I've ran the UHF notch duplexers back wards and they have ran ok, but the insertion loss does go up like 1-2dB. If you want to get picky you would have to modify each set so that the coupling loops and coaxes are the same, but probably wouldn't be worth the effort. That are modify the coaxes so the low frequency goes through all 6 low notch cavities and the same for the high. The isolator system is the way to go for repeaters, but not desireable for simplex radios. You'd have to split out the seperate RX and TX lines and then have a multicoupler and filter for the receivers and another antenna. On Thu, Jul 15, 2010 at 6:10 PM, n...@no6b.com wrote: At 7/15/2010 13:53, you wrote: Maybe a pair of those 6 cavity mobile duplexers with the 5 MHz split can be configured as 6 notch sections each to reject the opposite frequency. and then combine them with a T to the antenna. Even though they're notch duplexers, each side has a very weak pass response, just enough so that you can't use the low pass side as a high pass. As a result, trying to use one as a 6-section notch filter by putting all the notches on the same frequency using the TX RX ports as input output won't work, as it would have several dB of loss @ 5 MHz offset, even more @ ~1.2 MHz. Another alternative to a full size 2 meter duplexer would be a dual isolator following by a pass cavity on each TX, then T the cans together using the correct phase-critical lengths of coax. Might be cheaper if you happen to have an inexpensive source for 4 VHF isolators. Bob NO6B Yahoo! Groups Links
Re: [Repeater-Builder] Transmitter Combiner
DCFluX dcf...@gmail.com wrote: Maybe a pair of those 6 cavity mobile duplexers with the 5 MHz split can be configured as 6 notch sections each to reject the opposite frequency. and then combine them with a T to the antenna. Lossy, but should be cheap, I've seen those go in the $20 range. On Thu, Jul 15, 2010 at 1:49 PM, MCH m...@nb.net wrote: About the only way is via a duplexer. (Cheap? Well... used??? ;- ) Joe M. na4it wrote: Is there a cheap way to combine two txcvrs into one antenna... 144.39 APRS and 145.550 packet? Yahoo! Groups Links
