LeoG

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.....👍

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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.
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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.

So this is a full spectrum tuned duplexer.  Says 550-725 on the label.

 
So have you tried this on other frequencies?
How about separating the RX and TX HTs.  Put on of them in a metal box to try to isolate it.
Maybe the common antenna is desensing the HTs

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.

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.

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

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

Happened a couple days ago. 

I had an Uncle who was an Admiral in the Navy out of Groton.  Passed away and only my Aunt is survived.  No one in Rhode Island that I know of LOL

Ya, thanks for the offer.  Up in CT so kinda far to travel.  But maybe I'll get sick of working up and take a couple days off and go visiting.  Got people as far down as Florida and Texas I'd like to meet up with some day to make the imaginary internet friend real friends.

No, directly from Btech.  I ordered the repeater from them.  They decided the duplexer was troublesome and sent me a new one already tuned to the GMRS spectrum.  I removed the old and installed the new.  I still have the old one, they didn't want it back.

I have the Btech RT50 and it has a full spectrum GMRS duplexer.  It says it's rated at .25µV at 12dB SINAD.  Can't say I can prove it but it seems to receive well for the antenna and it's height.
 
This is the replacement duplexer they sent me.  The originals sensitivity was much worse than the replacement.  Tuned full band.

All I got was a card and love from my family.🥰