A Reversed Triplexer w/3 Tuned Antennas

[HappilyRetired]

I have picked up a couple more antennas much to my wife's disliking. I have one for low-band CHP, one for VHF High for the Forest Service and Cal Fire, and the UHF for LACoF or SCBoF. Currently they are on a switch so I can't keep changing the antennas.

A ham radio friend of mine told me to get something called a "triplexer" and reverse it. A Diamond MX2000 Triplexer, Low 1.6-60 MHz, Mid 110-170 MHz, High 300-950 MHz seems to be the one. He says the laws of physics will take over from there if I plug the low band into the low band porch, the VHF High into the middle court and the UHF for 800 end of the third port.

Does this really work? I can use three band specific antennas on one radio and physics will pick the correct antenna? I was terrible at math and sure didn't take physics in school.

 

[ve3ext]

used frequently in ham multi band transceivers., for sure it works

Jerry VE3EXT

 

[KevinC]

Works fine for me.

 

[Project25_MASTR]

Motorola actually has a whitepaper for using their triplexer (VHF/UHF/7-800) to split an APX8000 install into individual antennas (I think it was written for cases where there was a "dual band" APX6500 or XTL with antennas already in-place or in cases where certain antenna solutions were needed.

 

[mmckenna]

Does this really work? I can use three band specific antennas on one radio and physics will pick the correct antenna? I was terrible at math and sure didn't take physics in school.

That is exactly what it is designed to do.
The triplexer has tuned circuits that combine the 3 different RF ports into one common port. It'll work in either direction, as in 3 different band radios into one common antenna, or three different band antennas into one radio.

 

[HappilyRetired]

Wow! I had no idea this was so common. I purchased a Child's low band base antenna and I can hear CHP San Diego to Los Angeles to the Inland Empire. But I didn't know how to add a VHF high band antenna for CDF and Forest Service. Thank you ALL for your replies.

 

[mmckenna]

Wow! I had no idea this was so common. I purchased a Child's low band base antenna and I can hear CHP San Diego to Los Angeles to the Inland Empire. But I didn't know how to add a VHF high band antenna for CDF and Forest Service. Thank you ALL for your replies.

Well, if you didn't need UHF, an easier/cheaper solution would be to use a 5/8 wave VHF high band antenna. Those act as a base loaded 1/4 wave on VHF low. Won't perform well on UHF, though.

 

[HappilyRetired]

Well, if you didn't need UHF, an easier/cheaper solution would be to use a 5/8 wave VHF high band antenna. Those act as a base loaded 1/4 wave on VHF low. Won't perform well on UHF, though.

That's an interesting tidbit. I already have a Child's low band base antenna. It's about 10 ft tall and does quite well. I can hear San Diego up in into the San Bernardino and Indio and even into the Los Angeles division quite well. I especially can hear the units when they go on talk around channel 2. I find it interesting that CHP Dispatch can actually hear the units on channel 2 even though they're normally repeated on channel 1. I guess that's a good thing that what's it called failover in case the repeater goes down? LAPD we would go to our station channel either repeat or simplex. We would actually have unscheduled drills where we would switch to our station for dispatch simulating that dispatch was down for some reason. We had MCDC for Metropolitan LA and VCDC for the valley.

 

[Checkerboard]

Wow! I had no idea this was so common. I purchased a Child's low band base antenna and I can hear CHP San Diego to Los Angeles to the Inland Empire. But I didn't know how to add a VHF high band antenna for CDF and Forest Service. Thank you ALL for your replies.

This is a heckuva great idea! I am in CA also, and CHP low band on 42.30 is weak on my new SDS-200. I have a spare Diamond triplexer I can try. I've used one in my mobile Kenwood TM-742, which is VHF, 220, and 440. KM6U

 

[HappilyRetired]

This is a heckuva great idea! I am in CA also, and CHP low band on 42.30 is weak on my new SDS-200. I have a spare Diamond triplexer I can try. I've used one in my mobile Kenwood TM-742, which is VHF, 220, and 440. KM6U

I got my VHF base station antenna off eBay from a gentleman by the name of Bruce Childs brucechilds05. I don't see a listing for the antenna but if you're looking for a base antenna that is his eBay handle. The antenna works quite well and I'm told it's the same style antenna used by CHP. It is an exceptional performer. I can now hear the units when they're talking on the output of the repeater. They come in loud and clear even from Los Angeles and San Diego. Just depends on where they're at. Using a reversed triplexer I'm now able to connect multiple antennas to one scanner. After decades in a patrol car I'm not overly anxious to put a scanner in the car. But I guess if you're looking for performance in a mobile I saw Larson low band mobile antennas on eBay. I guess you could mix and match?