LeoG

Here's another vid showing a tune of a duplexer on a non vna.
 

Send them that bug report.
 

All my contacts with customer support for Tidradio have been positive. They've never told me no we won't replace it.  And they've never asked for the old one to be returned.

Send them that bug report.
 

Send them that bug report.
 

That's what I meant

That's what I meant

That's a good question, but not the way receivers get rated.  The sensitivity is the 'receiver' sensitivity. 
 
A couple points about how the duplexer work and why the receive sensitivity isn't impacted.  The duplexer filters out the receive frequency on the transmit side, and the transmit frequency on the receive side.  There is no direct impact to the signal due to tuning.  The only real 'reduction' would be the overall reduction in signal from insertion loss.  However, you may see a difference/improvement due to the filtering for another reason.
 
The cavity filters have a bit of a floating echo effect, with the dB of suppression wildly varying.  Your duplexer, for example, floats between -85dB and -110dB per cavity pair.  With a varying isolation of -170dB to -220dB.  Prior to tuning, the duplexer isolation floated between about -45dB and -70dB.  This can impact how much desense the receiver experiences, giving you the impression that receive sensitivity improved. 
 
To summarize, while the receive sensitivity doesn't improve with improved duplexer tuning, the improved filtering removing more of the transmitter signal and reducing desense, will allow the appearance of improved sensitivity.  

Had that happen to my H3.  Was in a building and wanted to see if I could hit my repeater.  I couldn't.  It was strange cause I was pretty close by.  Then I drove by it and still couldn't hit it.  Somehow my tones got changed and all I had to do is restore them and bingo, success.
It can happen.

That sounds more like they were both set to narrow and the other radios were set to wide.

Ya, 2 months ago.

Wait and save up some more money.  $100 isn't going to get you a quality setup.  It'll be more satisfying if you start off with a nice setup instead of replacing it a few time and buying the same thing more than once.
I would start with an antenna with a 7.2dBi gain and some LMR400.  Find out what it costs and save up for it.  You'll also need a chimney mount or roof mount which is going to add to the price tag.  Along with minor things like cable clips, water proofing, tools for installation etc.
 
If you are insistent on getting something up now then go with some sort of a mobile antenna.  Even something small mounted up high is going to be better than something inside the house on a lower floor.

Ya, 2 months ago.

Here's my little setup.  Nothing outrageous, but not necessarily simple.

And the approx parts list, some smaller stuff not included.

Wait and save up some more money.  $100 isn't going to get you a quality setup.  It'll be more satisfying if you start off with a nice setup instead of replacing it a few time and buying the same thing more than once.
I would start with an antenna with a 7.2dBi gain and some LMR400.  Find out what it costs and save up for it.  You'll also need a chimney mount or roof mount which is going to add to the price tag.  Along with minor things like cable clips, water proofing, tools for installation etc.
 
If you are insistent on getting something up now then go with some sort of a mobile antenna.  Even something small mounted up high is going to be better than something inside the house on a lower floor.

Wait and save up some more money.  $100 isn't going to get you a quality setup.  It'll be more satisfying if you start off with a nice setup instead of replacing it a few time and buying the same thing more than once.
I would start with an antenna with a 7.2dBi gain and some LMR400.  Find out what it costs and save up for it.  You'll also need a chimney mount or roof mount which is going to add to the price tag.  Along with minor things like cable clips, water proofing, tools for installation etc.
 
If you are insistent on getting something up now then go with some sort of a mobile antenna.  Even something small mounted up high is going to be better than something inside the house on a lower floor.

Yep, I can't wait to do a real world test when I put it back in the RPT50 Btech.  Right now I have a wide band tuned duplexer in it that they sent as a replacement.  And this duplexer worked much better than the one I gave Marc to tune.  As soon as I swapped out I noticed a marked improvement in reception.  Not sure how it's tuned, if it's the same tuning as the one I gave to Marc or something else.  It's probably tuned better than the original just from the fact I could get better reception out of it.
I've done a lot of real world testing with my current setup.  I know where I can hit it and where I can't and where it's iffy.  It's the iffy spots I'm hoping to see better results.
And Marc I just want to say it so the people here see it too.  Thanks for doing this.  I appreciate your effort and I'm looking forward to putting it to good use.  I know you just wanted to play with your toys, but it's hopefully going to be a real world difference for my repeater.  This way we can both have our fun.  And just think, now I'll have that other duplexer.....👍

Yep, I can't wait to do a real world test when I put it back in the RPT50 Btech.  Right now I have a wide band tuned duplexer in it that they sent as a replacement.  And this duplexer worked much better than the one I gave Marc to tune.  As soon as I swapped out I noticed a marked improvement in reception.  Not sure how it's tuned, if it's the same tuning as the one I gave to Marc or something else.  It's probably tuned better than the original just from the fact I could get better reception out of it.
I've done a lot of real world testing with my current setup.  I know where I can hit it and where I can't and where it's iffy.  It's the iffy spots I'm hoping to see better results.
And Marc I just want to say it so the people here see it too.  Thanks for doing this.  I appreciate your effort and I'm looking forward to putting it to good use.  I know you just wanted to play with your toys, but it's hopefully going to be a real world difference for my repeater.  This way we can both have our fun.  And just think, now I'll have that other duplexer.....👍

All my contacts with customer support for Tidradio have been positive. They've never told me no we won't replace it.  And they've never asked for the old one to be returned.

Yep, I can't wait to do a real world test when I put it back in the RPT50 Btech.  Right now I have a wide band tuned duplexer in it that they sent as a replacement.  And this duplexer worked much better than the one I gave Marc to tune.  As soon as I swapped out I noticed a marked improvement in reception.  Not sure how it's tuned, if it's the same tuning as the one I gave to Marc or something else.  It's probably tuned better than the original just from the fact I could get better reception out of it.
I've done a lot of real world testing with my current setup.  I know where I can hit it and where I can't and where it's iffy.  It's the iffy spots I'm hoping to see better results.
And Marc I just want to say it so the people here see it too.  Thanks for doing this.  I appreciate your effort and I'm looking forward to putting it to good use.  I know you just wanted to play with your toys, but it's hopefully going to be a real world difference for my repeater.  This way we can both have our fun.  And just think, now I'll have that other duplexer.....👍

-------------------------------------------------------------------------
EDIT:  It looks like the duplexer is still failing.  Another member pointed out another thread with a similar failure with the same make and model duplexer.  While the owner was pushing 70w+ through this 50w duplexer, this may fall into the 'buyer beware' category.  If you are going to try it, be sure you stay under the rated limit of 50w for longevity. BTech has it rated for a 50% duty cycle as well.
-------------------------------------------------------------------------
Hey folks!  For people looking for an affordable duplexer that works well, I may have a solution for you.
 
For those of you who have been following the thread, you may be aware that our friend @LeoG had a problem with a duplexer in his B-Tech repeater.  They exchanged it for him, but I offered to take a look at the duplexer, hoping that we could get a spare available, or a second for another machine.  I have to say, I am impressed.
 
The duplexer is a SGQ-450D.  It is a traditional six cavity mobile duplexer, made in China, and the cost is about $115-$120.  When I first got the duplexer, I connected it to a VNA.  The unit looked like it was tuned perfectly, the notch and SWR were great... it was just on the wrong frequency, preventing it from working on GMRS.  I connected it to a radio and a dummy load, checking both sets of filters, and it worked perfectly.
 
The downfall with duplexers setup like the ones installed in the B-Tech repeaters isn't the duplexer itself, but rather the tuning.  What companies do to make these wideband (and what I found with this duplexer), they tune the 3 receive cavities to slightly overlap instead of perfectly align. Also, the 3 transmit cavities to slightly overlap instead of perfectly align.  What you end up with is about 500KHz-700KHz of filtering at about 45dB-50dB on each side, for a max of about 100dB of isolation.  While not terrible, it leaves a lot of room for improvement, which is easily accomplished if you align all 3 cavities to work on the same frequency.
 
@LeoG asked to have the duplexer aligned to 462.600/467.600.  On the high side, I was able to get a minimum of -85dB notch centered at 462.600MHz.  On the low side, I was able to get a minimum of -87.4dB notch centered at 467.600MHz.  That is better than -172dB of isolation... almost double what the previous tune was.
 
Here are the final tune-up results.
Isolation = > -172dB
Transmit SWR = 1.08:1
Receive SWR = 1.18:1
Loss due to SWR = 0.0064dB
Total Insertion Loss is <1dB
 
For a test, I hooked it up to my portable repeater while at my house.  I got the same range as with my personal duplexer.  For comparison, these specs are on par with my SinTech/Sinclair duplexer, which is priced 4 times higher than the SGQ-450D.  The duplexer will be shipped back to Leo next week.  I am looking forward to his real-world feedback after the tune-up.
 
Below are a few images of the duplexer and the tuning results.  
 

 
 

 
 

 
 

 
 

Wait and save up some more money.  $100 isn't going to get you a quality setup.  It'll be more satisfying if you start off with a nice setup instead of replacing it a few time and buying the same thing more than once.
I would start with an antenna with a 7.2dBi gain and some LMR400.  Find out what it costs and save up for it.  You'll also need a chimney mount or roof mount which is going to add to the price tag.  Along with minor things like cable clips, water proofing, tools for installation etc.
 
If you are insistent on getting something up now then go with some sort of a mobile antenna.  Even something small mounted up high is going to be better than something inside the house on a lower floor.

Ya, lithium ion and other lithium derivative batteries have an onboard Battery Maintenance System to make sure the cells stay balanced and don't go over any specs.  Prevents over charging and bad events such as fires and explosions.  It's what turns the charging off when the battery is full.

Just because it looks like it, doesn't mean it is.  But in this case I think the cat squished the roof.

The new fangled radios are all computers now.  And just as any computer might need the occasional reboot so do radios.  Having to do the reset is just a step farther.  I had to do it on one of my Wouxun radios that was acting weird.  Fixed it up and I just hooked it up to the computer and reflashed my channels back into it.  5 minutes and done.
But this would be a serious problem if it was an emergency.  Good old fashion radio guts with no computer can have an advantage sometimes.  Same goes with automobiles.