Re: [Repeater-Builder] Someone want to spot me?
Just split the duplexer and you one half of it into your receive line. Tune it up to pass your 434.xxx channel, then fight with the rejection for your 442.675 channel. You should see 60+ dB of reject. (HINT - one most of those duplexers (if I remember right), there is an adjustable cap down in between the rejection sliders that will allow you to finesse that thing for odd ball operations). I have some link radios running within 0.3 MHz of my repeater transmitter with no desense ... vertical isolation and a directional link antenna better than any duplexer! James WJ1D Ken Arck wrote: Ok, so here's the deal I'm running a high power UHF repeater that transmits on 442.675 (60 watts out of duplexer). As part of the same system, there is a link receiver on 434.xxx. The link receiver is being de-sensed by the repeater xmtr (I'm guestimating around 6 dB or so). While I consider a better radio for the link, I'm thinking of a quick solution. As I have some extra Batwing T-1500 series cavities laying around, I'm thinking about terminating one port with a 50 ohm load and T'ing the other port into the link receive line and tuning the cavity for (obviously) 442.675. I'm thinking cable length between the T and the cavity is kinda irrelevant in this case. Sound about right? Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em! Yahoo! Groups Links
Re: [Repeater-Builder] Someone want to spot me?
Ken, If your T1500 cavity is the loop type such that the SO239's are closer to the tuning screw, you can set the pass to 434.xxx and the reject to 442.675, but might have to move the stationary knob to the outer position to get greater than a 5Mhz split. Rejecting that way is only effective for the transmitter freq. - those cavities don't have much pass protection. If you have a 1507 type pass-only (no notch knobs), then simply tune for 434.xxx pass - that will protect the receiver to a point (probably -25dbm per can). I have a 40W UHF test machine running with two narrowband GM300's and a 1507 with no desense. Wondering what link radios your looking at (can reply privately if you want). Tony Ken Arck wrote: Ok, so here's the deal I'm running a high power UHF repeater that transmits on 442.675 (60 watts out of duplexer). As part of the same system, there is a link receiver on 434.xxx. The link receiver is being de-sensed by the repeater xmtr (I'm guestimating around 6 dB or so). While I consider a better radio for the link, I'm thinking of a quick solution. As I have some extra Batwing T-1500 series cavities laying around, I'm thinking about terminating one port with a 50 ohm load and T'ing the other port into the link receive line and tuning the cavity for (obviously) 442.675. I'm thinking cable length between the T and the cavity is kinda irrelevant in this case. Sound about right? Ken - - - - - - President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcon trollers. com/ http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp. net http://www.irlp.net We don't just make 'em. We use 'em! Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Someone want to spot me?
Thanks for the replies folks - some good ideas. I should have clarified that the spare T-1500 cavities I have are BP only. And my plan is to use it as a suck-out (notch) filter. That is why I was talking about using a T in line with the receive line. Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em!
Re: [Repeater-Builder] Someone want to spot me?
At 09:28 AM 4/1/2010, KT9AC wrote: I have a 40W UHF test machine running with two narrowband GM300's and a 1507 with no desense. Wondering what link radios your looking at (can reply privately if you want). ---Believe it or not it's a MastrII Exec Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em!
Re: [Repeater-Builder] Someone want to spot me?
On 4/1/2010 12:40 PM, Ken Arck wrote: Thanks for the replies folks - some good ideas. I should have clarified that the spare T-1500 cavities I have are BP only. And my plan is to use it as a suck-out (notch) filter. That is why I was talking about using a T in line with the receive line. Ken -- *Theoretically* (I've never done it), you should be able to tune the cavity for the 442 freq, with a 'T' on the input, then on the output, cut a 1/4- open stub. The stub should reflect a short at it's resonant freq, and the cavity will pass that freq to the short, and kill it. *Theoretically* (YMMV, Not responsible for loss, Some restrictions apply, See your dealer for details. Taxes an batteries not included...) Jim
RE: [Repeater-Builder] Someone want to spot me?
I sat back and waited for all the responses, and you're on the right track. I've done this using band pass cavities on both UHF and VHF. The only error is that you should not terminate the cavity with a 50 ohm load. You will be able to see the difference (terminated, then unterminated), assuming you are using a spectrum analyzer and tracking generator. Last, you can cascade cavities to increase the suck out notch. Yes, the cable length is critical. Bill W6CBS Thanks for the replies folks - some good ideas. I should have clarified that the spare T-1500 cavities I have are BP only. And my plan is to use it as a suck-out (notch) filter. That is why I was talking about using a T in line with the receive line. Ken
Re: [Repeater-Builder] Someone want to spot me?
Remove one of the coupling loops and replace it with a metal hole plug, the cavity will then turn into a notch. Place either 1/4 electrical wavelength cable or 1/2 wavelength between the Tee and the cavity if you desire a high pass or low pass peak to the notch. On Thu, Apr 1, 2010 at 9:40 AM, Ken Arck ah...@ah6le.net wrote: Thanks for the replies folks - some good ideas. I should have clarified that the spare T-1500 cavities I have are BP only. And my plan is to use it as a suck-out (notch) filter. That is why I was talking about using a T in line with the receive line. Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em! Yahoo! Groups Links
