What's A Diplexer/Duplexer/Transmitter Combiner...

At the club yesterday someone asked how a couple of local AM stations shared the same antenna. A quick look at a commercial VHF in-band high-band PMR transmitter combiner/duplexer rated for 50 Watts. And a much smaller, much wider bandwidth, out of band amateur "duplexer" that allows me to run my ancient FT736R VHF/UHF base station on one antenna. Out of band = one TX & RX on VHF, the other TX & RX on UHF. Compare the size of the in-band commercial VHF duplexer to the out of band VHF/UHF "duplexer".

[@alaska3333]

You can actually transmit and receive at the same time with the shown duplexer, albeit crossband 144 440 as stated. For single band repeater use i.e. TX= 145.600 MHz / RX= 145.000 MHz (with a separate transmitter and receiver) this filter lacks the necessary isolation between the TX and RX frequency which is only 600 KHz shift (here in Europe). 73!

[@jay-rus4437]

Ive been unclear about one detail. Can I use a duplexer to connect two transceivers that are both dual band to a single dual band antenna? So can ai monitor a local 2m repeater on one transceiver, while simultaneously monitoring another 2m repeater on the second transceiver....while transmitting on one or the other? I hear a lot about one transceiver being 2m, while the other transceiver being 70cm.....but not both being 2m. I dont want to transmit from one transceiver and risk damaging the second transceiver

[@Jay-hr9ci]

and I assume you can receive on both 2m and 70cm at the same time?

[@Scotscan]

Very informative thanks. God knows why 5 people gave it a thumbs down

[@vk6cs456]

Thanks for the feedback. 5 gave it a thumbs down, I didn't notice. Still, it looks like it got a lot more thumbs up than thumbs downs. You can never please everyone.

[@johnnyray1121]

+VK6CS The people who voted thumbs down are too stupid to follow your instructions.

[@knanderson791]

I beg your pardon. I'm extremely stupid and I was able to follow along. Not because of my profound ignorance but because of this gentleman's mastery of communication and empathy for empty headed dodos like me.

[@alexgottmituns7049]

Say I want to transmit at 900Mhz using two antennas (3db and 10db. both omnis. The location is high, hilly but has a great line of sight) . Can it be done?

[@jay-rus4437]

Recently purchased a Comet CF-4160J Duplexer, however it behaves like what I understand a diplexer to be. Why cant the manufacturers even get these terms correctly? It causes a lot of confusion

[@anthonygallo3576]

Great vid , but i have to ask, i have a wideband discone antenna. Can i use either to recieve only on both my scanner and shortwave radio/ air band at the same time.? No transmitting involved???

[@zameerbux9737]

I'm not to sure if I can explain this well enough for you to understand but IL give it a try... My neighbor has a satellite TV and we applied for extra view ( I'm piggybacking off his decoder, so his decoder is the primary decoder and mine is the secondary) i ran a cable from his decoder using a diplexer ant 5-860MHz Sat 950 - 2150 MHz to mine. Do I need another diplexer or can I use a duplexor?

[@johnnyray1121]

This guy knows his stuff.

[@BocaAvilez]

you only need this if you need to use the same antenna. best is to just use it for the receiver alone. transmitter works beast with its own antenna. it will save you set up.

[@Jay-hr9ci]

I;ve watched all of your videos. What diplexer/duplexer do you recommend for a mobile setup? 144 and 430? 2 Antenna and one radio. Thank you

[@khodges2]

So would I used (2) Diplexer to connect my OTA & Comast Internet to my house & still have it work?

[@khodges2]

Currently I can't get my modem to connect to the internet. My last resort might be to move the modem to the same port as the one the TV is coming out of.

[@vk6cs456]

Sorry Kierre... no idea on that one.

[@jeffrcrc2332]

Couldn't the duplexer be used for 2 passive antennaes set for stations in different directions for a TV

[@vk6cs456]

Probably, but why not just connect the antennas through a TV antenna splitter. Instead of having two TVs connected to one antenna, have two antennas connected to the ports, it's unlikely the TV stations would be on the same frequencies if they were located so close together geographically.

[@MaximumEfficiency]

can you combine analog and digital signals from 2 sources?

[@bakersdirtydozen]

You'd need a same band combiner. Typically in telecom this product has a small portion of the band reserved for CDMA (voice) and the remainder of the block is for LTE (data). The way it's typically done is by using ceramic resonators and incorporating multiple capacitive/inductive notches between the channel edges for a sharp roll-off but, you will lose a small portion of the band.

[@MaximumEfficiency]

tnx, will try

[@KA9DSL]

Very few hams know the difference between a cavity duplexer and a diplexer.

[@kansas7614]

Can you use this unit for 2 uhf radios to 1 antenna? 1 for RX and 1 for TX, Do I need a Diplexer or Duplexer, Sorry I'm new this ham radio.

[@vk6cs456]

If you want to build a repeater that transmits and receives on the same antenna at the same time using different frequencies you need a duplexer. The small diplexer shown here would be unsuitable.

[@kansas7614]

VK6CS Thank you,. Yes that's what I want to build. Do you have any recommendations?

[@vk6cs456]

Unfortunately not. The ones I use/tune at work are made by RFI but I suspect they're probably quite expensive. Try Google, that's probably your best bet. Just type in 'buy duplexer for UHF repeater' and see what comes up. There are videos on You Tube showing people making UHF cavity filters out of large coffee cans, so if money is tight you could look at doing something like that.

[@kansas7614]

Than you VERY much for your reply's, The money is no problem, I just seen these ant was wanting to know if they would work before I bought one.

[@zevak1]

I’m doing the same thing as Kansas and I didn’t have a clue what that thing was called, cheers

[@marquieskendrick3407]

Can you take a Diplexer and use it in reverse?instead of 2 to 1; Can we do 1 to 2?Thanks

[@vk6cs456]

So, 2 radios to one antenna? It depends on the type of diplexer and the output power of the radios.

[@HamRadioDX]

Yes. But there has to be enough isolation on the diplexer that won't put power into the other radio.

[@AnTiThesis-HaT-HoT]

Thanks, interesting stuff, the reality of it isn’t so straightforward then. My little knowledge just grew a bit.

[@vk6cs456]

Thanks Sean. Amateur radio is all about learning.

[@peterclifford8305]

Helpful explanation… Cheers!

[@vk6cs456]

peter clifford Thanks Peter.

[@charliefizfaz373]

Great video and explanation. Thanks Peter. KC1EGU

[@vk6cs456]

Thanks for the feedback Charlie.

[@jcharos7672]

I added to my watch later. I drank to many beers.

[@vk6cs456]

Cheers...

[@anilkumar-ul6qx]

lol

[@matthewlee2686]

This fella passed away from alcoholism. Rip