wqpn591

The BF-8FHP will transmit on both GMRS and HAM VHF/UHF. Had to get mine on Amazon.

Agreed. Since the cable that came with it was shielded and had shielded RJ45, figured the socket was grounded. But did not look.

I do not. Unfortunately. I have a nano-VNA but dont want to damage port 2 trying to measure it. However, I did take my XLT duplexer and tuned Ant-High side port to filter the Tx freq. Took out my broad band attenuator and put that in. Made a huge difference in my receive sensitivity. Instead of my receive signal getting attenuated by 26dB, its now only 2dB but the Tx freq gets attenuated 38dB. Works like a champ. Did a little field testing and this works in places I figured it would not do to some rolling hills. Its a work around until I can do something with that Sinclair Duplexer.

Yeah that CAT5e is shielded with shielded ends. Tried a low freq ferrite on that too. No change.

Did one more experiment. Took the receive signal from the duplexer and instead of going into my Rx KG1000G, I connected it to a HT unit tuned to receive on my Rx freq. Sure enough, that one keys up also. I'm about 99% convinced that I'm getting leakage through the duplexer.

Did some more experiments today. Changed out all coax cable to better RG400 cables. Results: no change disconnected antenna and connected a 50ohm load. Results: no change. So its not the antenna itself. Put ferrite suppressors on all power lines to radios and AC power to power supply. Results: no change. but have some better material #61 ferrites on order to better suppress high freq. Measured insertion loss of my powered off preamp in line with Rx radio. That is 26dB loss without power and 14dB gain with power. So somewhere between 0 and 26dB attenuation stop the re-keying of the Rx unit. Put heavy duty aluminum foil over Tx and Rx unit. Results: no change. Not sure if those cases are metal or not. I need to find an RF meter to measure what is coming from duplex to Rx radio. Which is on a different frequency so this whole thing is strange.

Still doing some debug. Given the non-shielded radios theory, I'm going to focus on that next. Here is a video of what the units do. https://1drv.ms/v/s!ApcwUuoTYXaIhMB874A38r6NDNsX7w?e=rmYu3r and a pic of the box.

Thanks for the clarification between repeater hang time and squelch tail. I am using CTCSS on the Rx and Tx devices in the repeater so CSQ should not be a factor. Its actually performing pretty well now, as far as the repeater hang time being predictable, as long as the Rx unit does not re-key as a result of Tx signal getting back to the Rx input. My Sinclair MR356-N-2 was tuned to my frequencies. And since my nano-VNA unit is less accurate than the equipment they probably used, cant really verify without taking to someone with good test equipment. The test results sheet provided with the Sinclair show 82dB of attenuation Since even Medium power (20W (43dBm)) triggers the Rx but low (5W (37dBm)) does not, seems like only 6dB of attenuation would do the trick. can easily get that by using my XLT duplexer tuned as a high pass filter. Then I may be able to turn on the 12dB preamp to improve my intended receive signal. The receive sensitivity of the KG1000-G in the datasheet is 0.25uV which is about -119dBm. Not sure what it takes to break squelch. But with 82dB of attenuation of a 37dBm signal, I'm guess its North of -45dBm. if it can even be calculated this way.

I got my programming cable and did change the setting in the radio. it seems to be called "Hold time of Repeater". Set it to 1000ms on the Tx unit and now I have an intentional squelch tail. BTW, it did not do anything to also put it in the Rx unit. So only needs to be in the Tx unit. As it turns out, when I was testing prior, I had left the Tx unit on low power and the Rx unit does not breaks squelch when the Tx unit is keyed up. But with the Tx unit id on M or H power levels, indeed the Rx unit hears it. I disconnected the Tx cable to the duplexer and terminated into a 50ohm load and Rx unit does not hear it. So still getting some leakage through the duplexer. I put a preamp unit in line between the duplexer and Rx radio and left it powered down to get some insertion lost. That seems to allow me to Tx on max power without the Rx unit hearing it. But not sure about the hit to my Rx sensitivity. have to do some field testing. Was thinking about taking a second duplexer and tune it specifically to give me further filtering to the Rx unit. Thoughts?

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Well guys, I think I got this figured out. With your help. I went to try two things. Key the Tx unit and see if the Rx unit activates. And it did. Just when I was reaching over to adjust the power level down I noticed that the coax connector on the Tx unit was not fully tight. Tightened that up and bingo...........no more activating when the Tx unit is keyed up. Must have had some leakage detected by the Rx unit. And the tail is completely gone now. Maybe because I turned RPT-TONE off which brings up the question. what do you guys set the Repeat-hold-time to? The description in the manual is a bit confusing to me. It's unclear if the "PTT on the radio" is the kg1000g Tx unit or an external unit like an HT transmitting to the repeater. How do you guys interpret this? Repeat Hold Timer (Programming Software Only) The Repeating Hold Timer is used to prevent the PTT from being used to transmit too frequently. When the PTT on the radio is released after transmitting in repeater mode, the hold time prevents the unit from transmitting for a predermined interval while waiting for a response. If no valid QT/DQT is detected within the hold time, the transmitter will release the hold and allow the PTT to transmit. The repeating hold timer sets the hold time for the transmitter to resume transmitting 100ms-5000ms (5 seconds) after the received QT/DQT signal disappears. This function is only accessible and configured through the KG-1000G programming software.

I do use CTCSS codes. Duplexer is specifically tuned to my freq of use. the test results show -82dB attenuation from Tx to Rx. I'll try lower Tx power and see if that helps. The Rx light does stay on the whole tail time.

I did follow this recommendation to eliminate the Squelch tail but no real change. Wouxun Archives - Buy Two Way Radios

I've built a repeater using dual KG1000G units and a Sinclair duplexer. It seems to work just fine except that most of the time (not every time) the Tx continues 15-20sec after the end of PTT transmission. My testing is with Wouxun kg905g HT units. Occasionally the squelch tail is just a second or two. More reasonable. Anyone have a tip or reason on how to shorten the squelch tail?

I traded out my XLT-50 duplexer for a Sinclair Technologies MR356-N-2. Ordered it tuned to the channel I wanted to use. Ordered from the theantennafarm.com Works much better, and costs $500 instead of $150. But we get what we pay for. I also send my XLT-50 to John at BuyTwoWayRadios.com and he is tuning it to my freq so I'll try it again when it comes back.

Very nice side-by-side comparison. Exactly what I was seeing on the XLT. Your insertion loss is right on target and the nice deep notches........ I ended up ordering the Sinclair MR356N-2 from theantennafarm.com. will see how that does.

Well, after trying to tune that XLT DP-GMRS-50 duplex with a nanoVNA, I've concluded that indeed, the filter design is just not tight enough and there will always be loss through this thing. If the freq spread where 8Mhz or more, it would work nicely. But at the 5Mhz spread we have in GMRS, its very hard to get low loss on both the Rx and Tx sides at the same time. I'm going to try a better mobile duplexer from Sinclair MR3332B-3. They tune it to order, with something better than a nanoVNA I presume. Still wont be as good at the notch-pass type of duplexer but dont want to fork over $3K+ and loose my mobile friendly system. Will let you guys know how that one does when it comes in.

Thanks for the info all. 2dB target is not horrible but can try to make up with antenna gain. Right now I'm just testing with RG58 short jumpers into a dummy load. Bought a nanoVNA and will try to tune this thing for low drop on my frequencies of interest. I'm trying to make this repeater mobile so I can take to our volunteer group events and easily set it up for better coverage than we could get on Simplex. so I'm a little limited on room for the duplexer. A better one that is a little bigger would be fine. But one of those big can units wont fit. I'll check out some of the units that @JeepCrawler98 suggested.

Its an XLT DP-GMRS-50 duplexer. Bought it with the radios from buytwowayradios.com . made for GMRS repeaters. I guess I need to find a VNA and see if its tuned correctly.

I'm building a GMRS repeater with two Wouxun KG-1000G units. Doing some bench testing and noticed that when I put my Nissei RS-50 SWR meter inline with an XLT 50W dummy load, I get SWR 1.02 and power 42W. But when I run the signal through the XLT DP-GMRS-50 duplex and measure to the same load, I get SWR 1.0 and power 9W. Is it customary to lose that much power through a Duplexer?