New gear for aligning duplexers

[paulears]

I've had to return the 'borrowed' gear I've been using for quite a long time, and have lost the ability to align duplexers. In reality I probably only do this three or four times aa year, so I don't wish to spend stupid money. I've lost track of the current popular kit people are using - I'm seeing very clever stuff with comparators, memories, and other stuff you'd like to have if you do this every day, but all I need is to be able see what the tuners are doing, optimise the bandwidth and get a reading on the isolation I've achieved. Bells and whistles above this would be a waste.

Any advice folks? Even perhaps ones that might come up from time to time second hand, as long as they were still useful. A search here in the UK has proven fruitless so far, so I'm considering importing something if it is sensibly priced.
Thanks
Paul

 

[N4GIX]

I own a Rigol DSA815 spectrum analyzer with tracking generator. At ~$1500 USD it isn't the most expensive by far, but does get the job done.

 

[com501]

HP8920 or 8924 would do nicely, and do most anything else you wanted to do also.

 

[zz0468]

HP8920 or 8924 would do nicely, and do most anything else you wanted to do also.

I second the motion, and the 8924c goes on eBay for about $800usd. They both are very capable machines. Add the 8935 to the list, as well.

I actually have one of each. Love 'em all.

 

[lmrtek]

To tune a duplexer properly you need a tracking generator

You would be far better off to pay a radio shop to tune the duplexer if you don't have the means to buy a service monitor with a tracking generator

I routinely get duplexers in the shop from hams that THINK they know how to tune duplexers and they only wind up damaging the adjustments to the point of no return

The most critical component of a repeater system is the duplexer so it pays to take it to a PROFESSIONAL

 

[zz0468]

To tune a duplexer properly you need a tracking generator

All of the suggested units have spectrum analyzer with integral tracking generator.

I routinely get duplexers in the shop from hams that THINK they know how to tune duplexers and they only wind up damaging the adjustments to the point of no return

I'm all in favor of hams screwing it up a few times while they learn how to do it right.

But the OP never actually stated he was a ham working on ham gear...

The most critical component of a repeater system is the duplexer so it pays to take it to a PROFESSIONAL

But there's no guarantee that paying for it will get it done right.

 

[zz0468]

Any advice folks? Even perhaps ones that might come up from time to time second hand, as long as they were still useful.

Yes. Why limit yourself to just tuning duplexers? If you're playing with this sort of stuff, once you have a more complete set of instruments, you'll wonder how you did without it. And some gear is so fun to play with, you end up pulling it out more than 4 times a year just to use it more than 4 times a year.

Look for used HP gear built for the cellular market. But do a bit of research, too. Much of that stuff has analog service monitor and spectrum analyzer functions, but a few similar items don't. Just be sure of what it is you're buying.

 

[speedway_navigator]

https://youtu.be/Md6lFOKvJzI

good video on preselector and duplexer tuning, the only one I've seen that uses the Smith chart function for fine tuning.

 

[RFI-EMI-GUY]

The HP8920B, 8924 and 8935 are great bargains. You do need to make sure option 102, the spectrum analyzer is fitted. There is a yahoo group dedicated to the HP8924 where you can get the latest on all the related models and capabilities.

 

[paulears]

To tune a duplexer properly you need a tracking generator

You would be far better off to pay a radio shop to tune the duplexer if you don't have the means to buy a service monitor with a tracking generator

I routinely get duplexers in the shop from hams that THINK they know how to tune duplexers and they only wind up damaging the adjustments to the point of no return

The most critical component of a repeater system is the duplexer so it pays to take it to a PROFESSIONAL

Indeed - and my first licence to sell, install and repair professional radio equipment was taken out in 1986 when I started my radio business, and back then we did it with a manually tuned signal generator and had to plot the response curves on graph paper, which made tuning somewhat more time consuming than the modern systems.

The one that I've had to return was an HP 9593, that has done stirling service over the years, but my colleague has moved out of the area and we can't collaborate any longer as he's approaching retirement. I've no real need for the real gizmos, as I said, just enough to continue aligning duplexers, and the occasional cavity.

I'll have a look at the 8900 series as they've certainly moved on, and appreciate the point that I would probably spend longer using a modern unit because of what it can do - as said, maybe things that I've never really thought about.

I do appreciate the point about the quality of some mobile style duplexers. I've had a few from China, and while they tuned quite nicely, the actual metal used seems quite soft and it's very easy to strip the threads. I've no idea what the inside is like, having never destroyed one, but they seem pretty stable. The alloy just seems to need careful treatment.

Thanks folk!

 

[RFI-EMI-GUY]

Indeed - and my first licence to sell, install and repair professional radio equipment was taken out in 1986 when I started my radio business, and back then we did it with a manually tuned signal generator and had to plot the response curves on graph paper, which made tuning somewhat more time consuming than the modern systems.

The one that I've had to return was an HP 9593, that has done stirling service over the years, but my colleague has moved out of the area and we can't collaborate any longer as he's approaching retirement. I've no real need for the real gizmos, as I said, just enough to continue aligning duplexers, and the occasional cavity.

I'll have a look at the 8900 series as they've certainly moved on, and appreciate the point that I would probably spend longer using a modern unit because of what it can do - as said, maybe things that I've never really thought about.

I do appreciate the point about the quality of some mobile style duplexers. I've had a few from China, and while they tuned quite nicely, the actual metal used seems quite soft and it's very easy to strip the threads. I've no idea what the inside is like, having never destroyed one, but they seem pretty stable. The alloy just seems to need careful treatment.

Thanks folk!

HP8593?

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[PACNWDude]

+1 on the HP8920B/Opt 102. These have been the workhorse for tuning duplexers for many years. Worked for a company that had a dozen of these, and they all started to burn up power capacitors. After re-capping them, they are once again working like new.

You can also buy duplexers from Tessco, and have them tuned before delivery for a fee. However, like others have said, there is no guarantee that the person doing the work knows what they are doing. We had a few come to us out of alignment a bit.

 

[paulears]

Yep - sorry, typo in the number. 8593 was it! Thanks for the correction. It had behaved itself very well and the only real issue was the up and down buttons were a little sticky. I'll have a look and see if one of the suggestions comes up on ebay - and so far, UK ones are right at the top end price wise.

 

[RFI-EMI-GUY]

Yep - sorry, typo in the number. 8593 was it! Thanks for the correction. It had behaved itself very well and the only real issue was the up and down buttons were a little sticky. I'll have a look and see if one of the suggestions comes up on ebay - and so far, UK ones are right at the top end price wise.

If I recall, HP was manufacturing the 8920 in the UK which should be good from the standpoint of local supply. In the US, so many were sold for the Cellular and PCS development that the prices plummeted when those companies moved off shore. My 8920B unit came from a dealer in Lynchburg VA, which once was an Ericsson phone plant. It had very low time and was free of any dust inside. I bought it with a 5 day right of refusal which sealed the deal for me once I saw it.

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[paulears]

I'll have a dig up and see what the differences are from my old one - I've never had a need for more than 470MHz or so, so GHz top end performance is not important for me. My colleague has suggested I have a look at the Rigol 815 which I can get for around the thousand pound mark - which seems pretty good. I also hadn't realised HP is now also rebranded in the test gear market as Agilent? Things certainly have moved on.

 

[RFI-EMI-GUY]

I'll have a dig up and see what the differences are from my old one - I've never had a need for more than 470MHz or so, so GHz top end performance is not important for me. My colleague has suggested I have a look at the Rigol 815 which I can get for around the thousand pound mark - which seems pretty good. I also hadn't realised HP is now also rebranded in the test gear market as Agilent? Things certainly have moved on.

Carly Fiorina destroyed HP test and measurement company. The T&M was spun off as Agilent, now struggling as Keysight, and shareholders lost a ton of money. I am one of them. The whole operation smelled of fraud.

She reduced the top manufacturer of scientific , medical and labratory instrumentation into a company that manufactures mediocre color printers. I don't think I have ever seen such a great accomplishment short of what Donald Trump plans to do on a daily basis.

Fiorina is a business failure and political hack who should never have been selected to operate any business more complex than a coffee stand. She is the business equivalent of Sarah Palin, and she also has similar political aspirations.

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[mancow]

I picked up an HP8935 off ebay a year ago for $600. You can't beat them for the price.

 

[mikewazowski]

I use an HP8921 to tune multicoupling and duplexors.

 

[paulears]

Wow - I didn't know any of this behind the scenes stuff, and I feel for RF-EMI-GUY - it does sound extremely fishy.

All my previous HP kit - mainly three different signal generators and some video kit was built to really last - perhaps in the modern world this isn't exactly good for repeat business?

The new stuff is as good?

 

[rescue161]

I loved my HP8924C. The resolution was very good and mine had the high-power option that would allow 100W input so tuning radios was a breeze. I sold it when i got an R2670, but the 2670 sucked for doing filter work. The only thing I hated about the 8924 was the weight/size. It was almost 70 pounds, so lugging up to tower sites was horrible. I looked around for a portable spectrum analyzer with a tracking generator for a while and then settled on the Siglent SSA3021X. I like it better than the HP8924, mainly because it is very portable; it weighs about 10 pounds. Navigating the screens is very easy and the bandwidth/resolution is very nice. Gets way more detail than the 8924 could and allows up to 4 markers & colored traces. There is a marker screen that can be viewed at the same time that gives detailed info of all four markers. I could never go back to the HP. I'm also glad that I went with this unit instead of the Rigol DSA-815-TG due to the specs and hack-ability of this unit.

Now, with that said, is it lab-grade? No. Will it replace a VNA? I think not. Will it allow you to align cans with ease for about $1650? Absolutely! I bought it from Saelig.com and used a super-secret coupon code that I had to register to EEVBlog forum to get the code. It was worth it as it saved me 6%. I got the SA with the TG for $1658.16 shipped (shipping is free). That is about $105 cheaper than anywhere else. I ordered it on 15 Aug 2017 and it was at my house on the 18th.

Edit: I just checked and now they are offering the Tracking Generator for free, so if you are able to use the code, you can get what I got for $1499.30 - shipped. That is a heck of a deal. http://www.saelig.com/siglent-SSA3000x/ssa3021x.htm