Repeater Chinese Made Duplexer Review.

"OMG a little kid running around and a rifle on the table" one comment below states. Yeah well there are probably knives in the kitchen drawers too genius. The gun if unloaded and triple checked to be unloaded ALONG with teaching the kids not to touch it unless he's instructing them to do so and the gun is no more dangerous than the knives or scissors that are likely in the house. Use common sense before posting stupid comments like that. Good video on the duplexes btw, thanks.

been looking at these myself...have to see what kinda work comes up if I order one or not

I agree with Steve Wright. All I wanted to know in viewing this is what the insertion loss (mentioned), split (mentioned) and rejection (not mentioned, but somewhat readable in the video - see further comments). The comparison between a BR duplexer with a BPBR duplexer wasn't of much value. The rejection spec on these are typically -75 dB but I can't tell from this video if the device achieves the specified performance. It appears that the input signal is already attenuated and the measured rejection may be at the noise limit of the spectrum analyzer (the notch is at -95 dB with the reference signal at -40 dB, a rejection of only -55 dB). -35 dB rejection would be extremely bad. Unfortunately, I cannot determine if it is worth investing in one of these (my application would be a low power full duplex DMR hot-spot, where -75 dB rejection on a 5 MHz split is probably adequate. Sorry, but this video left me wanting. If this video were re-done with a higher reference signal that enabled the rejection to be measured, there would be great value in having that information.

Have not thought about it. It sounds like work, YT is a more enjoyable platform for me to express my ideas or experience through videos. I feel I get more info across a visual "show me" method than a 2 dimensional media like writing. Bottom line, I have to have fun doing it. Thanks for watching

The Decibel Dupl was actually a BP/BR duplexer, it had a built in Capacitor to adjust the notch/band reject. Unfair comparison, but its was all I had at the moment.

Thanks for keeping us informed.

It's a notch filter, not a bandpass/notch-reject filter like your large cans, and you are right to say this is not suitable for co-siting with other radio equipment.

I just have a question. I got one of these and my repeater TX is 462.675 and my RX is 467.675. I told the company to program the high to the 467 and the low to the 462. Am I correct?

we are using one of these in uhf band at a mountain top ( 8500 Ft). we have noticed that there is a loss in rx signal as compared to 2 antennas however it works fine till 110 miles with a 5 watt handy. cant complain given the pricing and its performance. ideal for where 2 antennas cant be installed. on the other hand we have a sinclair full size duplexer on vhf setup installed at the same location and thats a breeze but costs a fortune.

Outstanding GC.

Just to be correct, the mobile duplexer you tested is a reject only duplexer. The receiver side rejects it own transmitter and the transmitter side rejects its own receiver frequency.

Thanks for the video, greetings from Veracruz, México

Do you know of a low wattage duplexer? I'm building a SHTF duplex repeater system using handhelds, but I really need to find a light-weight and small duplexer for VHF.

I'm here because I bought a Fumei duplexer. I can get it to reject the opposing frequencies, but the desense on the receiving radio makes the repeater range shorter than just using an HT simplex.

I have one of the Chinese duplexers, mine had 3dB loss which is not even close to specs.  I have a Celwave US made duplexer that the Chinese copied to make the cheap ones you see on eBay. The Celwave brand met specs.  If you look closely on eBay they show a 10mhz frequency spread.  In the US normal UHF repeaters operate with a 5mhz frequency spread.  The narrower the spread the worse the Chinese models perform.  Who knows how they will stand up to temperature changes.  A good quality duplexer like the Bandpass/Bandreject duplexer you have is very stable in hot and cold temperatures.  The metal that makes up the tuning rods must be stable, not grow or shrink with temperature or the critical tuning will change.

Good comparisons, as I've been considering the China made. Now I'll be looking at older American made. Thanks

Don't know whee to find answer.. Working on a stealth repeater in my head. Want to put everything in a 4" sewer drain pipe, camoflage it, Could slip out to a ridge, and plant it, have a couple sticks for a 20' pole, small solar cell like yours attached towards the top. Can one of these notchers be taken apart to be two units or stacked so fit inside a 4" pipe? Thanks.

Intriguing at first until you learn that most from China on Ebay etc. specify a much wider minimum freq. separation than we typically use in the U.S. Quality duplexers provide about 80-85dB attenuation between high and low. Check this before you buy.

Ordered two of these from a Chinese manufacturer. Did not get around to using them for a few months and when I did they were badly tuned. A friend (40+ years of mobile radio experience) attempted to tune them and found the best he could get was 4db loss. Could not get them to tune properly at all. Compare that to the Cellwave mobile duplexer and no comparison. Cellwave tunes great. Of course seller would not honor warranty because it was only 30 days. Another lesson learned the expensive way. Maybe these are cheap knockoffs or they are seconds. Either way buyer beware.

Have you thought about authoring an ebook on amazon? A good basic explanation of some principles and some possible SHTF ideas for comms and etc? Thanks!