Re: [Repeater-Builder] Re: Band Pass Duplexer Tuning
On 2/22/07, fxbuilder [EMAIL PROTECTED] wrote: I didn't have a load on the 3rd port when I tuned it. I only have 1 dummy load. I can add an antenna to the 3rd port though I know that would less than ideal but better than nothing I suppose. I have found some schematics for the pads and will be working on that this weekend. On a side note anyone know what the sensitivity should be on my uhf Mitrek when it is tuned correctly? A low level but noisy signal seems to break squelch at .5mv (assuming I'm reading my old tube Navy generator correctly) and full quiet seems to be around 5mv. Is this close to what it should be? It just doesn't seem to have great ears. Could be the nearby hills are just heavily blocking the antenna. Finding a good location that doesn't cost my first born is tough in this area. Craig I'm not a Motorola guy, so I have no idea what the factory spec of the Mitrek receiver sensitivity is... but... For repeater service using older radios, it's pretty common to need a pre-amp to get maximum receiver performance. But your original posts were that you were tuning a small flat-pack style duplexer for this project -- it may simply not have enough rejection. Are you doing the sensitivity tests with the transmitter on or off? You could be fighting good old fashioned desense. A couple of the articles here in the RB site might be useful: http://www.repeater-builder.com/antenna/deaf.html (The link to Remec/Wacom in that article goes to someone else now... since Wacom was acquired... and the link goes to a redirect that leads to a company in Lynchburg who does other types of filters, looks like...) http://www.repeater-builder.com/rbtip/preamps.html ( I disagree with a statement in this article... If you have the ability you can probably construct a preamp that will more closely suit your needs than can be found commercially. -- Chip Angle at AngleLinear gets rave reviews from many repeater owner/operators, and a lot of us use Advanced Receiver Research's pre-amps without undue headaches... which are both commercial products. They both suit a lot of people's needs! GRIN... ) I'm also not quite sure about this statement talking about using the pre-amp after the duplexer and before the receiver... : Again, since we are not making up for a great deal of loss, we do not need a great deal of gain. This example works great in UHF systems but likely shouldn't be tried on 2 meters. Off the top of my head, I can think of more than five VHF systems here locally that do this with fine results...? Different clubs, different techs. Some have bandpass filtering, some don't... Kevin might explain what he was thinking there...? But anyway... check for desense before anything ... if you have that going on, making the receiver hear better will only make it worse. (GRIN) Nate WY0X
[Repeater-Builder] Re: Band Pass Duplexer Tuning
Ok... So I've tuned this duplexer as a notch device. Put a 2 watt handheld into a dummy load and watt meter (not in that order mind you) and it seems to reject the corresponding frequencies. My question now is... Why did my swr jump from 1:1.3 to 1:3. Do I need to re-tweek it? Also I'm noticing a huge power loss when measured before and after the duplexer. Talking 30 watts down to below 10 watts. Any suggestions. Perhaps it is time to check the cables etc? Thanks for all the help in the past. Craig --- In Repeater-Builder@yahoogroups.com, Gary Schafer [EMAIL PROTECTED] wrote: Lots of the small mobile duplexers (notch type) have fixed capacitors inside and you can only adjust the cavity tuning, which tunes the notch. This type duplexer is limited in how far from the design frequency you can tune it as the capacitors are fixed. The cavities will tune but the loss goes. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of fxbuilder Sent: Friday, February 16, 2007 5:09 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Band Pass Duplexer Tuning I emailed the place I bought it from and that is what I was told. Band Pass. No caps on it for notch tuning as on celwave. Am I missing something here? Craig --- In Repeater-Builder@yahoogroups.com, Ken Arck ah6le@ wrote: At 01:53 PM 2/16/2007, you wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Is there such a thing??? Ken -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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 Yahoo! Groups Links
Re: [Repeater-Builder] Re: Band Pass Duplexer Tuning
At 06:49 AM 2/20/2007, you wrote: Ok... So I've tuned this duplexer as a notch device. Put a 2 watt handheld into a dummy load and watt meter (not in that order mind you) and it seems to reject the corresponding frequencies. My question now is... Why did my swr jump from 1:1.3 to 1:3. Do I need to re-tweek it? Also I'm noticing a huge power loss when measured before and after the duplexer. Talking 30 watts down to below 10 watts. Any suggestions. Perhaps it is time to check the cables etc? Thanks for all the help in the past. ---What did you do with the 3rd port during your tuning procedure? When you tune a duplexer, did you MUST present a 50 ohm load on ALL 3 ports. This typically means using 3 (or 6) dB pads on all ports during tuning. Since yours is showing excessive loss and bad VSWR, my bet is you left the 3rd port unterminated and didn't use pads on at least the Port to which the radio was connected. Ken -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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
RE: [Repeater-Builder] Re: Band Pass Duplexer Tuning
Like Ken said; all 3 ports need to be terminated in 50 ohms when tuning. A signal generator is usually fairly close to 50 ohms, a receiver may or may not be, usually not. The unused port at the time needs a 50 ohm load. The best way is to use a 6 db pad on gen and rec sides while tuning. But what may be the worst problem is you may be trying to use it too far from the design frequency. You have no way to tune the loops on those units. Also be sure you haven't reversed the tx and rx frequencies as the loops are tuned internally to pass a frequency only on one side of the notch. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of fxbuilder Sent: Tuesday, February 20, 2007 9:49 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Band Pass Duplexer Tuning Ok... So I've tuned this duplexer as a notch device. Put a 2 watt handheld into a dummy load and watt meter (not in that order mind you) and it seems to reject the corresponding frequencies. My question now is... Why did my swr jump from 1:1.3 to 1:3. Do I need to re-tweek it? Also I'm noticing a huge power loss when measured before and after the duplexer. Talking 30 watts down to below 10 watts. Any suggestions. Perhaps it is time to check the cables etc? Thanks for all the help in the past. Craig --- In Repeater-Builder@yahoogroups.com, Gary Schafer [EMAIL PROTECTED] wrote: Lots of the small mobile duplexers (notch type) have fixed capacitors inside and you can only adjust the cavity tuning, which tunes the notch. This type duplexer is limited in how far from the design frequency you can tune it as the capacitors are fixed. The cavities will tune but the loss goes. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of fxbuilder Sent: Friday, February 16, 2007 5:09 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Band Pass Duplexer Tuning I emailed the place I bought it from and that is what I was told. Band Pass. No caps on it for notch tuning as on celwave. Am I missing something here? Craig --- In Repeater-Builder@yahoogroups.com, Ken Arck ah6le@ wrote: At 01:53 PM 2/16/2007, you wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Is there such a thing??? Ken -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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 Yahoo! Groups Links Yahoo! Groups Links
[Repeater-Builder] Re: Band Pass Duplexer Tuning
Yes there is... but it's really big even for UHF. Phelps Dodge Made one and I've seen a number of odd ball units around with Harris labels on them. Normally the smaller mobile duplexer are notch-pass (aka notch-notch). But everything is possible... and probably tried at least once. cheers, skipp Is there such a thing??? There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check.
[Repeater-Builder] Re: Band Pass Duplexer Tuning
I emailed the place I bought it from and that is what I was told. Band Pass. No caps on it for notch tuning as on celwave. Am I missing something here? Craig --- In Repeater-Builder@yahoogroups.com, Ken Arck [EMAIL PROTECTED] wrote: At 01:53 PM 2/16/2007, you wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Is there such a thing??? Ken -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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
[Repeater-Builder] Re: Band Pass Duplexer Tuning
If you are talking about a flat pak duplexer, they are easy. Hook a receiver (or scope) to the high side and set the monitor frequency to the low frequency. Inject the high freqency into the antenna port. Tune for the deepest null. Then hook the monitor to the low side set for the high frequency and inject the high frequency, and again, tune for the deepest null. You will have to keep readjusting your signal generator. It helps to inject the 1000Hz tone if you are doing it by ear. Scott NA4IT --- In Repeater-Builder@yahoogroups.com, fxbuilder [EMAIL PROTECTED] wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Craig
[Repeater-Builder] Re: Band Pass Duplexer Tuning
Yes, this is a flat pack. The place I bought it from told me it was a band pass. Thanks Scott, I'll try your method. Craig --- In Repeater-Builder@yahoogroups.com, Scott [EMAIL PROTECTED] wrote: If you are talking about a flat pak duplexer, they are easy. Hook a receiver (or scope) to the high side and set the monitor frequency to the low frequency. Inject the high freqency into the antenna port. Tune for the deepest null. Then hook the monitor to the low side set for the high frequency and inject the high frequency, and again, tune for the deepest null. You will have to keep readjusting your signal generator. It helps to inject the 1000Hz tone if you are doing it by ear. Scott NA4IT --- In Repeater-Builder@yahoogroups.com, fxbuilder fxbuilder@ wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Craig
Re: [Repeater-Builder] Re: Band Pass Duplexer Tuning
At 02:14 PM 2/16/2007, you wrote: Yes, this is a flat pack. The place I bought it from told me it was a band pass. Thanks Scott, I'll try your method. Craig Don't! Scott is talking about a notch type duplexer, not a pass band one. Ken --- In mailto:Repeater-Builder%40yahoogroups.comRepeater-Builder@yahoogroups.com, Scott [EMAIL PROTECTED] wrote: If you are talking about a flat pak duplexer, they are easy. Hook a receiver (or scope) to the high side and set the monitor frequency to the low frequency. Inject the high freqency into the antenna port. Tune for the deepest null. Then hook the monitor to the low side set for the high frequency and inject the high frequency, and again, tune for the deepest null. You will have to keep readjusting your signal generator. It helps to inject the 1000Hz tone if you are doing it by ear. Scott NA4IT --- In mailto:Repeater-Builder%40yahoogroups.comRepeater-Builder@yahoogroups.com, fxbuilder fxbuilder@ wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Craig -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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
Re: [Repeater-Builder] Re: Band Pass Duplexer Tuning
At 02:09 PM 2/16/2007, you wrote: I emailed the place I bought it from and that is what I was told. Band Pass. No caps on it for notch tuning as on celwave. Am I missing something here? ---As Skipp pointed out, most the so-called mobile duplexers are notch only. You have a make and model #? Ken -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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
RE: [Repeater-Builder] Re: Band Pass Duplexer Tuning
Lots of the small mobile duplexers (notch type) have fixed capacitors inside and you can only adjust the cavity tuning, which tunes the notch. This type duplexer is limited in how far from the design frequency you can tune it as the capacitors are fixed. The cavities will tune but the loss goes. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of fxbuilder Sent: Friday, February 16, 2007 5:09 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Band Pass Duplexer Tuning I emailed the place I bought it from and that is what I was told. Band Pass. No caps on it for notch tuning as on celwave. Am I missing something here? Craig --- In Repeater-Builder@yahoogroups.com, Ken Arck [EMAIL PROTECTED] wrote: At 01:53 PM 2/16/2007, you wrote: There is a great article on this site about tuning a notch duplexer by Kevin. Can similar methods be used for tuning a mobile 6 can band pass duplexer? Is there an article that I missed that explains it as easily? I need to re-tune and could use the help. I think I know how but thought I'd check. Is there such a thing??? Ken -- President and CTO - Arcom Communications Makers of the world famous RC210 Repeater Controller 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 Yahoo! Groups Links
