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Suggestions for service monitor

 

With SDR being a thing these days, is there any software that could turn say a BladeRF into a capable service monitor for duplexer tuning and alignment? Or any off the shelf solutions which just connect to a computer with USB for operating the service monitor so you don't need the expense of a box with everything in it, similar to the USB oscilloscopes?
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If not, what is the best bang-for-your-buck ebay-able service monitor that is suitable for most basic service/alignment tasks on repeaters/mobiles/duplexers?
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Thanks,
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Mike
 

Motorola R2600 series with tracking generator option.
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One and done.
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Chris/AJM
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--
Chris Baldwin, CETSr. (KF6AJM)
Trustee - MetroNET Cal. Intertie (KB3PX)
 

Try a LibreVNA. They are both a VNA and Spectrum Analyzer that run though USB to a computer.?
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Rob VK5TRM
 

Ramsey COM3010
It does everything I need for AM/FM communication transceivers and duplexer tuning.

Alan N2ZVN

On Sun, Apr 6, 2025 at 9:49?AM Mike Bernardo KI5ANU via <mike=[email protected]> wrote:
With SDR being a thing these days, is there any software that could turn say a BladeRF into a capable service monitor for duplexer tuning and alignment? Or any off the shelf solutions which just connect to a computer with USB for operating the service monitor so you don't need the expense of a box with everything in it, similar to the USB oscilloscopes?
?
If not, what is the best bang-for-your-buck ebay-able service monitor that is suitable for most basic service/alignment tasks on repeaters/mobiles/duplexers?
?
Thanks,
?
Mike
 

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Thanks! Pricey though, except maybe for the CRT models. Makes me a little nervous to go spending $2500 on something with an old CRT in it. I was just reading this here which is interesting, some amount of restoration is possible and I wonder if any of these SimmComm Labs LCD replacements would work for a Motorola service monitor:?

Mike

On Apr 6, 2025, at 09:43, Chris Baldwin via groups.io <vtat1271@...> wrote:

Motorola R2600 series with tracking generator option.
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One and done.
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Chris/AJM
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--
Chris Baldwin, CETSr. (KF6AJM)
Trustee - MetroNET Cal. Intertie (KB3PX)
 

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Ooh this is interesting. I have a NanoVNA and I think I asked here and also saw some other threads here that were saying its dynamic range is not enough to tune a duplexer. LibreVNA looks a lot more capable!

Mike

On Apr 6, 2025, at 14:38, Rob VK5TRM via groups.io <vk5trm@...> wrote:

Try a LibreVNA. They are both a VNA and Spectrum Analyzer that run though USB to a computer.?
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Rob VK5TRM
 

At 4/6/2025 01:35 PM, you wrote:
Ooh this is interesting. I have a NanoVNA and I think I asked here and also saw some other threads here that were saying its dynamic range is not enough to tune a duplexer. LibreVNA looks a lot more capable!

I've seen reports of drift issues with the LibraVNA.? For the moment I'm happy with my VNWA 3EC (though the design is getting dated so not sure I'd recommend for a new purchase), but if I needed one today I'd try this one: <>

Bob NO6B

 

The NanoVNA-V2 seems to handle doing the pass part pretty well. You're measuring return loss there, and it seems to handle that just fine. Only question I might se is if the frequency standard is really accurate enough to set it correctly-but I bet it's pretty close...
Notches on the other hand-forget it. Definitely not even close to enough range for that. Even most service monitors can't do it, or are right on the edge of doing tolerably.

On 4/6/2025 5:34 PM, Bob Dengler via groups.io wrote:
At 4/6/2025 01:35 PM, you wrote:
Ooh this is interesting. I have a NanoVNA and I think I asked here and also saw some other threads here that were saying its dynamic range is not enough to tune a duplexer. LibreVNA looks a lot more capable!
I've seen reports of drift issues with the LibraVNA.? For the moment I'm happy with my VNWA 3EC (though the design is getting dated so not sure I'd recommend for a new purchase), but if I needed one today I'd try this one: < <>>
Bob NO6B
_._,_._,_
 

For non digital stuff the HP/Agilent 8920 series.?
 

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I second this. I had the same question about a month ago and ended up getting an HP8921A. It’s a good analyzer to learn on and does probably way more than you need.?


On Apr 7, 2025, at 6:42?PM, Mike via groups.io <prcradio@...> wrote:

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For non digital stuff the HP/Agilent 8920 series.?
 

I bought a Motorola R2600C for $600 and then about a week later picked up a Motorola R2550 with tracking generator for $400. I already have a Rigol DSA815TG spectrum analyzer that I use for filter tuning.
 

Third.

Bob NO6B

At 4/7/2025 03:47 PM, you wrote:

I second this. I had the same question about a month ago and ended up getting an HP8921A. It?�?s a good analyzer to learn on and does probably way more than you need.


On Apr 7, 2025, at 6:42?�?PM, Mike via groups.io <prcradio@...> wrote:

???
For non digital stuff the HP/Agilent 8920 series.

 

Mike,
This is a Windows program, but I think it's a lot of what you want and you can choose the hardware
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Steve N4IRS
 

The Motorola 2600 series is hard to beat... And can be found reasonably priced if you are patient.


On Tue, Apr 8, 2025, 7:10?AM Steve N4IRS via <szingman=[email protected]> wrote:
Mike,
This is a Windows program, but I think it's a lot of what you want and you can choose the hardware
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Steve N4IRS
 

Steve, I have RSP Spectrum Analyzer made for the RSP line of inexpensive SDR receivers and while it works well and is cute, its just a toy. Alignment of repeaters which I take as tuning the receiver for best sensitivity, placing it exactly on frequency, measuring the repeater transmitter frequency, measuring transmit deviation, transmit power then possibly sweeping and aligning the duplexer and associated filters and isolator is beyond what a toy SDR could ever do. Amateurs don't have to abide by most FCC specs when placing an amateur repeater on the air but it still takes some accurate and reliable equipment to align all its parts for proper operation. That can be done with a separate frequency measuring device, signal generator, deviation meter and duplexers/filters can certainly be aligned with a CW signal generator and power/millivolt meter or even a diode detector and oscilloscope.?
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When I started in Land Mobile alignment and repair we had mostly separate instruments to perform everything and when I finally got my hands on a Singer FM10C in the 70s I though I had died and gone to heaven. I can't imagine any SDR receiver performing the type of simple tests an old FM10C can do without a host of other expensive equipment to calibrate it or verify if its even within spec. Heck, just the frequency standard in the old FM10C probably cost way more than the BladeRF SDR mentioned. I would recommend getting the best actual radio service monitor that the OP can afford and trade up in the future to a better model. Many good suggestions have been made here but there are also older more affordable models that will work great to get someone started.

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