[GMRS Repeater]

Well it comes down how much money you want to put into the system

Cavity duplexers get pricey.

I have used those Fumei duplexers and they do a good job so long they are tunned precisely.

It is granted there will be RF loss but that happens with coaxial lines alone

Important thing in mind to keep is that you want to have acceptable SWR to prevent damage to the transmitter.

I have heard so much negativity from hams and gmrs folks alike about those darm chinese duplexer but it is all about name brands.

they are not perfect chinese made devices but not too different than the US made

From my experience I agree 100% I have a Fumei duplexer now tuned at -90 to -95 dB and with good 7/8 heliax it transmits almost exactly what the theoretical map say 50W at 55’ in my location will cover. It’s so good that now I just got a Decibel Products BpBR and I’m afraid the losses will be higher than the China flat pack.

[ICOM FR4000 programming question.]

FR4000 up and running fine as far as the repeater itself. I can’t hear any audio from the onboard speaker or the internal speaker. I think I’ve turned off 5tone as the instructions indicate if you want to listen from the repeater. I’m sure the front panel speaker mute isn’t on... any idea? RX and TX work great, just can’t hear the repeater in the shop.

 

Thanks!

[GMRS Repeater]

There is always some loss, however your SWR should be low. High SWR means you have a lot of power returning to the transmitter. Granted 2.4 is still bad, I've seen it as high as 19:1. The BP/BR duplexer loses 3-8W depending on how much power I put in.

 

 

 

 

Not on a flatpack at 460M. The nano VNA stops reading at levels below -60DB. I tried this several times and while I think it'll be in the neighborhood and could be used to test the duplexer, I wouldn't attempt to tune a 460 duplexer with it.

 

I tried it. It’s exactly what WRAK968 said. -60dB would be Max with the noise floor, and the sweep is real slow. I’ve tuned lots of similar devices, I took mine over to friend with a service monitor to see how close I was. Best I could do was about -60 on 466.52 vs the 467.575 I was tuning for. If you nailed it you would be lucky. My repeater had RX desense because I tried the NanoVNA, now it’s a 20 mile repeater once I put the Amazon duplexer on the service monitor.