RE: [Repeater-Builder] dual band convertacom
Albert, I had a very similar installation as you describe in my car, and I used a dual-band brick PA with my setup. 5W VHF yielded 50W / 4W UHF yielded 40W. My biggest issue with the setup was they side contacts on my radios wouldn't make good contact all the time with the MVA, so I yanked it in favor of a dual-band mobile. But I still have the MVA and the PA, just in case... ;-) Seeing you prefer to use separate PAs, you might want to consider two diplexers - one ahead of each PA to "split" the feedlines and then one behind them to "re-combine" them. But to be honest, IMHO this is kinda the "Rube Goldberg" way of doing it, I think. Compare prices - by the time you get the diplexers and other stuff, you may well be approaching the cost of one dual-band PA. Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of hitekgearhead I know I am going to get the singular answer of "WHY" but I really would like some technical input on this. In my car I have an old Genesis series convertacom connected to a dual band Comet antenna. I often will swap my VHF and UHF HT back and forth and utilize the dual band capability of my antenna. It works pretty well. What I would like to get some input on however, is how to run some power with this setup. Of course the easiest would be to get a amateur dual band amplifier, but I already have a VHF and a UHF (N1275A and N1274A) amplifier. What I would like to do is parallel these two amps with some kind of switching/duplexer setup so that I could easily switch from VHF to UHF. My initial idea was to run an antenna switch from the convertacom to the amps so I can manually select which one the signal goes to. Then on the output side of the amps I thought about using an antenna duplexer on the output of the amps to feed the antenna. I was also thinking of running a switch to alternately select which amp was receiving DC power, but I don't know if that would be necessary. (Could I leave both amps powered on in this situation?) So, does this sound about right or am I going off the deep end? Thanks Albert
Re: [Repeater-Builder] dual band convertacom
On the comment below all I can mention is from my experience which may or may not be valid in this case. When running amplifiers through diplexors as suggested I have damaged the out put transistors on both units, no I am not sure exactly what did it but as both amplifiers failed my guess is as one came up to full power and the other went non linear something happened and the diplexor failed to isolate as desired and expected. If anyone can sort out what happened let me know --- On Wed, 2/24/10, Kris Kirby wrote: From: Kris Kirby Subject: Re: [Repeater-Builder] dual band convertacom To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 24, 2010, 11:01 AM On Wed, 24 Feb 2010, hitekgearhead wrote: > What I would like to do is parallel these two amps with some kind of > switching/duplexer setup so that I could easily switch from VHF to > UHF. > > My initial idea was to run an antenna switch from the convertacom to > the amps so I can manually select which one the signal goes to. Then > on the output side of the amps I thought about using an antenna > duplexer on the output of the amps to feed the antenna. I was also > thinking of running a switch to alternately select which amp was > receiving DC power, but I don't know if that would be necessary. > (Could I leave both amps powered on in this situation?) > > So, does this sound about right or am I going off the deep end? Buy two duplexers (diplexers) from some ham source, put one between the MTVA and the amps, and the other between the amps and the antenna. No switching needed. If one really wanted to get wonky, you'd put another MTVA in the car and use a linear dual-band HT amp, but you'd have to look at the third-order intercept points on a spectrum analyzer to make sure the amplifier doesn't create mixing products, and alter the drive level of the two HTs to make sure the amp doesn't go non-linear when trying to amplify 145MHz and 440MHz at the same time. -- Kris Kirby, KE4AHR Disinformation Analyst Yahoo! Groups Links
Re: [Repeater-Builder] dual band convertacom
On Wed, 24 Feb 2010, hitekgearhead wrote: > What I would like to do is parallel these two amps with some kind of > switching/duplexer setup so that I could easily switch from VHF to > UHF. > > My initial idea was to run an antenna switch from the convertacom to > the amps so I can manually select which one the signal goes to. Then > on the output side of the amps I thought about using an antenna > duplexer on the output of the amps to feed the antenna. I was also > thinking of running a switch to alternately select which amp was > receiving DC power, but I don't know if that would be necessary. > (Could I leave both amps powered on in this situation?) > > So, does this sound about right or am I going off the deep end? Buy two duplexers (diplexers) from some ham source, put one between the MTVA and the amps, and the other between the amps and the antenna. No switching needed. If one really wanted to get wonky, you'd put another MTVA in the car and use a linear dual-band HT amp, but you'd have to look at the third-order intercept points on a spectrum analyzer to make sure the amplifier doesn't create mixing products, and alter the drive level of the two HTs to make sure the amp doesn't go non-linear when trying to amplify 145MHz and 440MHz at the same time. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] dual band convertacom
Try using a dual amp. And dual antenna then you won't forget to switch. Just my 2 cents Ki4ljm Marc Lonstein M.O. Unlimited Inc. P.O. Box 5364 Fort Lauderdale, FL 33310-5364 Ph: 954-720-9200 Ph: 561-368-3557 Fax: 561-368-1885 <mailto:m...@mounlimited.com> www.mounlimited.com This e-mail transmission contains information intended only for the use of the recipient(s) named above. Further, it contains information that may be privileged and confidential. If you are not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this message (including any attachments) is strictly prohibited. If you have received this e-mail in error, please notify the sender by reply e-mail and then delete this message from your e-mail system. Thank you for your compliance. -Original Message- From: Chris Quirk Date: Wed, 24 Feb 2010 09:17:00 To: Subject: Re: [Repeater-Builder] dual band convertacom 2 coaxial switches will work, and you could leave power on. Given that I know what I am capable of and this type of system would lead to muliple failures by me as I failed to remember to switch things. If it was me I would just move the coax connectors as I swapped radios. I have done something like this in the past and got irritated and tossed the whole thing is favor of a wide band type of amp, which also has its issues of tuning and retuning --- On Wed, 2/24/10, Lee Pennington wrote: From: Lee Pennington Subject: Re: [Repeater-Builder] dual band convertacom To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 24, 2010, 9:07 AM Not why but WHY !! On Wed, Feb 24, 2010 at 11:56 AM, hitekgearhead wrote: I know I am going to get the singular answer of "WHY" but I really would like some technical input on this. In my car I have an old Genesis series convertacom connected to a dual band Comet antenna. I often will swap my VHF and UHF HT back and forth and utilize the dual band capability of my antenna. It works pretty well. What I would like to get some input on however, is how to run some power with this setup. Of course the easiest would be to get a amateur dual band amplifier, but I already have a VHF and a UHF (N1275A and N1274A) amplifier. What I would like to do is parallel these two amps with some kind of switching/duplexer setup so that I could easily switch from VHF to UHF. My initial idea was to run an antenna switch from the convertacom to the amps so I can manually select which one the signal goes to. Then on the output side of the amps I thought about using an antenna duplexer on the output of the amps to feed the antenna. I was also thinking of running a switch to alternately select which amp was receiving DC power, but I don't know if that would be necessary. (Could I leave both amps powered on in this situation?) So, does this sound about right or am I going off the deep end? Thanks Albert -- "Always drink upstream from the herd."
RE: [Repeater-Builder] dual band convertacom
> My initial idea was to run an antenna switch from the > convertacom to the amps so I can manually select which one > the signal goes to. Then on the output side of the amps I > thought about using an antenna duplexer on the output of the > amps to feed the antenna. I think you'll find that using a second "duplexer" (cross-band coupler) on the input to the amps will be cheaper than buying a high-quality coaxial relay to switch between the two. Then you don't have to switch anything. > I was also thinking of running a > switch to alternately select which amp was receiving DC > power, but I don't know if that would be necessary. As long as the switch or cross-band coupler affords sufficient isolation to keep the "wrong" amplifier from switching into transmit mode, it shouldn't matter, unless you're concerned about battery drain. --- Jeff
Re: [Repeater-Builder] dual band convertacom
2 coaxial switches will work, and you could leave power on. Given that I know what I am capable of and this type of system would lead to muliple failures by me as I failed to remember to switch things. If it was me I would just move the coax connectors as I swapped radios. I have done something like this in the past and got irritated and tossed the whole thing is favor of a wide band type of amp, which also has its issues of tuning and retuning --- On Wed, 2/24/10, Lee Pennington wrote: From: Lee Pennington Subject: Re: [Repeater-Builder] dual band convertacom To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 24, 2010, 9:07 AM Not why but WHY !! On Wed, Feb 24, 2010 at 11:56 AM, hitekgearhead wrote: I know I am going to get the singular answer of "WHY" but I really would like some technical input on this. In my car I have an old Genesis series convertacom connected to a dual band Comet antenna. I often will swap my VHF and UHF HT back and forth and utilize the dual band capability of my antenna. It works pretty well. What I would like to get some input on however, is how to run some power with this setup. Of course the easiest would be to get a amateur dual band amplifier, but I already have a VHF and a UHF (N1275A and N1274A) amplifier. What I would like to do is parallel these two amps with some kind of switching/duplexer setup so that I could easily switch from VHF to UHF. My initial idea was to run an antenna switch from the convertacom to the amps so I can manually select which one the signal goes to. Then on the output side of the amps I thought about using an antenna duplexer on the output of the amps to feed the antenna. I was also thinking of running a switch to alternately select which amp was receiving DC power, but I don't know if that would be necessary. (Could I leave both amps powered on in this situation?) So, does this sound about right or am I going off the deep end? Thanks Albert -- "Always drink upstream from the herd."
Re: [Repeater-Builder] dual band convertacom
Not why but WHY !! On Wed, Feb 24, 2010 at 11:56 AM, hitekgearhead wrote: > > > I know I am going to get the singular answer of "WHY" but I really would > like some technical input on this. > > In my car I have an old Genesis series convertacom connected to a dual band > Comet antenna. I often will swap my VHF and UHF HT back and forth and > utilize the dual band capability of my antenna. It works pretty well. > > What I would like to get some input on however, is how to run some power > with this setup. > > Of course the easiest would be to get a amateur dual band amplifier, but I > already have a VHF and a UHF (N1275A and N1274A) amplifier. > > What I would like to do is parallel these two amps with some kind of > switching/duplexer setup so that I could easily switch from VHF to UHF. > > My initial idea was to run an antenna switch from the convertacom to the > amps so I can manually select which one the signal goes to. Then on the > output side of the amps I thought about using an antenna duplexer on the > output of the amps to feed the antenna. I was also thinking of running a > switch to alternately select which amp was receiving DC power, but I don't > know if that would be necessary. (Could I leave both amps powered on in this > situation?) > > So, does this sound about right or am I going off the deep end? > > Thanks > Albert > > > -- "Always drink upstream from the herd."
[Repeater-Builder] dual band convertacom
I know I am going to get the singular answer of "WHY" but I really would like some technical input on this. In my car I have an old Genesis series convertacom connected to a dual band Comet antenna. I often will swap my VHF and UHF HT back and forth and utilize the dual band capability of my antenna. It works pretty well. What I would like to get some input on however, is how to run some power with this setup. Of course the easiest would be to get a amateur dual band amplifier, but I already have a VHF and a UHF (N1275A and N1274A) amplifier. What I would like to do is parallel these two amps with some kind of switching/duplexer setup so that I could easily switch from VHF to UHF. My initial idea was to run an antenna switch from the convertacom to the amps so I can manually select which one the signal goes to. Then on the output side of the amps I thought about using an antenna duplexer on the output of the amps to feed the antenna. I was also thinking of running a switch to alternately select which amp was receiving DC power, but I don't know if that would be necessary. (Could I leave both amps powered on in this situation?) So, does this sound about right or am I going off the deep end? Thanks Albert
