RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
Yes you are right. I misread the frequencies involved and was thinking they were much closer spaced. 100 KHz is doable with cavity/isolator type combiners. Loss will run around 2 db or so. 73 Gary K4FMX > -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of nj902 > Sent: Monday, September 17, 2007 11:41 PM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner > > The T-Pass UHF transmitter multicoupler [e.g. 73-67-25-2C-03] from TX- > RX systems uses cavity-ferrite technology and can combine two > transmitters at a separation of only 75 KHz. "The loss ... is > comparable to that of a hybrid combiner, but T-Pass provides the > benefit of cavity selectivity for noise and intermodulation > supression." > > -- > --- In Repeater-Builder@yahoogroups.com, "Gary Schafer" > <[EMAIL PROTECTED]> wrote: > > "The only way to do the close spaced frequencies 447.750 and 447.850 > is with a hybrid type combiner. ..." > . > . > [mailto:[EMAIL PROTECTED] On Behalf Of Mike Mullarkey > > "...We need to combine TX 447.750, 447,850 and 464.900 into one > antenna. ...' > > > > > > > Yahoo! Groups Links > > >
[Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
The T-Pass UHF transmitter multicoupler [e.g. 73-67-25-2C-03] from TX- RX systems uses cavity-ferrite technology and can combine two transmitters at a separation of only 75 KHz. "The loss ... is comparable to that of a hybrid combiner, but T-Pass provides the benefit of cavity selectivity for noise and intermodulation supression." -- --- In Repeater-Builder@yahoogroups.com, "Gary Schafer" <[EMAIL PROTECTED]> wrote: "The only way to do the close spaced frequencies 447.750 and 447.850 is with a hybrid type combiner. ..." . . [mailto:[EMAIL PROTECTED] On Behalf Of Mike Mullarkey "...We need to combine TX 447.750, 447,850 and 464.900 into one antenna. ...'
RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of skipp025 > Sent: Monday, September 17, 2007 10:57 AM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner > > > The only way to do the close spaced frequencies 447.750 and 447.850 > > is with a hybrid type combiner. > > One is not restricted to using a hybrid... it's just a question of > how practical and cost effective going another route would be. > > Real world loss using a hybrid is over 4dB per leg... of which I'm > not a fan about space heating a radio vault with terminated rf power. > > The most practical choices are to be made when we hear if he wants > to use one or more antennas and any receiver requirements. > > cheers, > s. He said that he has only one antenna available in his post. No other way to do it that I know. 73 Gary K4FMX
Re: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
Jeff DePolo wrote: > You can do productive things with the hybrid's reject port power; it doesn't Good lord, I never even thought of that. Another one for the "file until you have a chance to try it out somewhere" file. LOL! Nate WY0X
[Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> The quadrature hybrid itself should only be 3 dB theoretically, > typically around 3.2 dB in the real world. It's the external > circulators that need to be added to get the necessary isolation > that bumps it up to around 4 dB. Yep, the overall package has much resultant baggage. > You can do productive things with the hybrid's reject port power; > it doesn't have to be connected to a dummy load. You can put an > isolator on it (to guarantee a good match to keep the hybrid's > isolation up), and feed the output to another antenna, such as > a corner reflector on the back-side of the tower to fill in the > nulls of your side-mounted omni. Waste not, want Now that's a neat idea... I'll file that in my head and claim local credit for it when no one here is paying close attention. Unless someone is really trying or just gets really lucky... it's my opinion the nulls from a side mounted omni shouldn't be that deep if it's properly offset from the tower/pole. Yeah... there would be viable applications where the main tx uses a corner reflector or similar directive antenna system and the otherwise wasted hybrid port power could be used to feed something directional the other direction. > not like my grandmother used to say. But make sure the IM > products are suitably attenuated; ferrites are non-linear devices > so they will create IM when passing two high-level signals. Quality bandpass cavities with sometimes optional harmonic filters are the bacon saving hardware. > Or, you can connect the reject port to a dump load to make a > nice warm place for mice to build a nest :-) > --- Jeff That's what the old user installed Tripp Lite Power Supply is for. How much crap can a mouse stuff into it before it fails. cheers Jeff, skipp
RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> Now that's a neat idea... I'll file that in my head and claim > local credit for it when no one here is paying close attention. > > Unless someone is really trying or just gets really lucky... it's > my opinion the nulls from a side mounted omni shouldn't be that > deep if it's properly offset from the tower/pole. Here in the lowlands where we don't have high mountains to put our repeaters on, we have big tall towers with 12' faces that are packed with TV and FM transmission lines that block RF from passing through the tower. Nulls off the backside over a fairly wide arc that are 30 dB deep or more are an unfortunate fact of life... --- Jeff
RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> Real world loss using a hybrid is over 4dB per leg... of which I'm > not a fan about space heating a radio vault with terminated rf power. The quadrature hybrid itself should only be 3 dB theoretically, typically around 3.2 dB in the real world. It's the external circulators that need to be added to get the necessary isolation that bumps it up to around 4 dB. You can do productive things with the hybrid's reject port power; it doesn't have to be connected to a dummy load. You can put an isolator on it (to guarantee a good match to keep the hybrid's isolation up), and feed the output to another antenna, such as a corner reflector on the back-side of the tower to fill in the nulls of your side-mounted omni. Waste not, want not like my grandmother used to say. But make sure the IM products are suitably attenuated; ferrites are non-linear devices so they will create IM when passing two high-level signals. Or, you can connect the reject port to a dump load to make a nice warm place for mice to build a nest :-) --- Jeff
[Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> The only way to do the close spaced frequencies 447.750 and 447.850 > is with a hybrid type combiner. One is not restricted to using a hybrid... it's just a question of how practical and cost effective going another route would be. Real world loss using a hybrid is over 4dB per leg... of which I'm not a fan about space heating a radio vault with terminated rf power. The most practical choices are to be made when we hear if he wants to use one or more antennas and any receiver requirements. cheers, s.
RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
The only way to do the close spaced frequencies 447.750 and 447.850 is with a hybrid type combiner. The other channel 464.900 can be added in to the antenna line with an isolator and a pass cavity or you could use a duplexer. But with a duplexer you have to be careful of IM products more so than when using an isolator. With an isolator and cavity type combiner the cables to the T or multi junction connector to the cavities are ¼ wave length. That length includes the loop length and is best obtained from the cavity manufacturer. The frequencies need to be far enough apart so that the cavity provides at least 10 db of skirt isolation to the other frequencies. You can think of the cavity as performing a switch action or disconnecting that part of the circuit from the other frequencies by enough so that it does not load down the other frequencies at the multipoint junction. The cavity operates as a short circuit (10 db down short at least) and the short gets transformed to an open thru the ¼ wave length line to the junction at the other frequencies. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Mike Mullarkey Sent: Sunday, September 16, 2007 10:58 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner HI Skip, Very tight outdoor cabinet. We need to combine TX 447.750, 447,850 and 464.900 into one antenna. I know this is not optimum but this is what we have to work with. Mike Mullarkey (K7PFJ) _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of skipp025 Sent: Sunday, September 16, 2007 9:05 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner There is more than one type of combiner possible... depending on frequency spacing, band of operation and power level. s. > "Mike Mullarkey" <[EMAIL PROTECTED]> wrote: > > Ok, I been all over the web and cant seem to find any documentation on the > critical cable lengths to build a 3 channel combiner. Does anyone happen to > have such a document. > > > > Thanks, > > > > Mike Mullarkey (K7PFJ) >
[Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> We need to combine TX 447.750, 447,850 and 464.900 into one > antenna. I know this is not optimum but this is what we > have to work with. The two Amateur Band Transmitters are 100KHz spaced with the commercial box more than 10MHz higher. To keep things short and sweet, the close spaced Amateur Transmitters are probably best done with a 2 port hybrid. Depending on your resources... the hybrid output would more often be bandpass combined with the 464 commercial box path. All this can be done on one or two antennas, just takes the proper hardware in place and a lot of homework. Making it fit into a very space limited cabinet is the magic trick. cheers, s.
RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
> > > > I would have interest in this also as I need to combine 443.150 and > > 462.600 to 1 ant > > thank you > > Merrill > > KG4IDD > > I'm just addressing the two-port project above-- would not an ordinary > duplexer work just fine? > > Laryn K8TVZ Yep, do it all the time. When combining transmitters, you need to pay careful attention to IM products as measured at the output of the combiner. While Part 97 is silent on the issue of spectral purity above 225 MHz, that doesn't mean you're off the hook if your IM products are bothering someone else. A good "cleanliness" spec to target for IM products is they should be 43 + 10 log (watts) down (e.g. -63 dBc for 100 watts of transmitter power). That spec will also satisfy Part 95 GMRS for the 462.6 transmitter. Measure the IM products at the antenna tee while both transmitters are keyed to ensure they are adequately attenuated. A duplexer with 60 dB or so of isolation should be more than adequate. If your transmitters already have isolators built in (Micor, MSF, PURC, etc.), you may only need two pass/reject cavities, one per side, to combine cleanly. --- Jeff
[Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
--- In Repeater-Builder@yahoogroups.com, Merrill <[EMAIL PROTECTED]> wrote: > > I would have interest in this also as I need to combine 443.150 and > 462.600 to 1 ant > thank you > Merrill > KG4IDD I'm just addressing the two-port project above-- would not an ordinary duplexer work just fine? Laryn K8TVZ
Re: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
I would have interest in this also as I need to combine 443.150 and 462.600 to 1 ant thank you Merrill KG4IDD Mike Mullarkey wrote: > > HI Skip, > > > > Very tight outdoor cabinet. We need to combine TX 447.750, 447,850 and > 464.900 into one antenna. I know this is not optimum but this is what > we have to work with. > > > > Mike Mullarkey (K7PFJ) > > > > *From:* Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] *On Behalf Of *skipp025 > *Sent:* Sunday, September 16, 2007 9:05 AM > *To:* Repeater-Builder@yahoogroups.com > *Subject:* [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner > > > > There is more than one type of combiner possible... depending on > frequency spacing, band of operation and power level. > s. > > > "Mike Mullarkey" <[EMAIL PROTECTED]> wrote: > > > > Ok, I been all over the web and cant seem to find any documentation > on the > > critical cable lengths to build a 3 channel combiner. Does anyone > happen to > > have such a document. > > > > > > > > Thanks, > > > > > > > > Mike Mullarkey (K7PFJ) > > > >
RE: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
HI Skip, Very tight outdoor cabinet. We need to combine TX 447.750, 447,850 and 464.900 into one antenna. I know this is not optimum but this is what we have to work with. Mike Mullarkey (K7PFJ) _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of skipp025 Sent: Sunday, September 16, 2007 9:05 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner There is more than one type of combiner possible... depending on frequency spacing, band of operation and power level. s. > "Mike Mullarkey" <[EMAIL PROTECTED]> wrote: > > Ok, I been all over the web and cant seem to find any documentation on the > critical cable lengths to build a 3 channel combiner. Does anyone happen to > have such a document. > > > > Thanks, > > > > Mike Mullarkey (K7PFJ) >
[Repeater-Builder] Re: 3 Channel UHF Ferrite Combiner
There is more than one type of combiner possible... depending on frequency spacing, band of operation and power level. s. > "Mike Mullarkey" <[EMAIL PROTECTED]> wrote: > > Ok, I been all over the web and cant seem to find any documentation on the > critical cable lengths to build a 3 channel combiner. Does anyone happen to > have such a document. > > > > Thanks, > > > > Mike Mullarkey (K7PFJ) >
