Radio Test Sets and related equipment

[btt]

Honestly, I’m not sure who’s being serious and whose joking! I’m too much of a noob lol!

-B

I think we're all joking a bit here. Seriously, don't buy those last few test sets.

 

[merlin]

I used a Systron Donner SLN6878 (same as Motorola) for a number of years, Swapped that out for a Cushman CE-50 I used for over a decade.
You may be able to find these under $2000 but they will fill your bill. May need work and recalibration.
I thought I was upgrading trading for Aeroflex 1900, but that became problematic then died. now it sits in storage collecting dust.
A caveat to the above is none do digital, and newer models that will are going to be very expensive. 5K and up.
Those Agilent sets are nice but they won't cover LMR frequencies.
cheers.

 

[KevinC]

I think we're all joking a bit here. Seriously, don't buy those last few test sets.

And I apologize for starting the silliness.

 

[RFI-EMI-GUY]

Seems to be turning into a thread on how to detune your receivers.

How so? All it takes is takes knowledge. It's a poor technician who blames his test equipment.

 

[btt]

How so? All it takes is takes knowledge. It's a poor technician who blames his test equipment.

Sorry, didn't mean to offend. Honestly, I think you should reserve judgement until after you use some test equipment that I designed.

 

[WA0CBW]

"btt" .....tell us more about your creations.
BB

 

[btt]

I was trying to continue the humor. (blaming your test equipment). Tough crowd.

 

[AM909]

I enjoyed the trip down memory lane.

As far as the topic at hand, depending on what you're working on, you might be able to get away with an older analog service monitor, supplemented with an SDR and software like SDR# and plugins, LTRAnalyzer, DSD+ (fastlane), PDW, SDRTrunk, etc. to decode various digital modes. Most digital radios have test modes that you can use to get the RF side of things aligned. Unless, you're going to be digging into the intricacies of the digital protocols (somehow), working on some site equipment, etc., that will get you there without breaking the bank.

As has been said, calibration is key. Having access to someone else's calibrated equipment is helpful. Anyone have experience with particular GPSDO models in the <$200 range? Is it really just a matter of plugging it into your 10 MHz external reference port and you get <0.1 ppm accuracy? Any thoughts on a budget-conscious calibration standard for RF and AF power levels?

ObClassicServiceMonitor:

 

[btt]

...
As has been said, calibration is key. Having access to someone else's calibrated equipment is helpful. Anyone have experience with particular GPSDO models in the <$200 range? Is it really just a matter of plugging it into your 10 MHz external reference port and you get <0.1 ppm accuracy? Any thoughts on a budget-conscious calibration standard for RF and AF power levels?

Yes. The GPSDO will become more accurate as you let it set there and warm up. The accuracy will vary depending on the number of satellites received and other factors. Accuracy is always down in the parts-per-billion for these inexpensive units. I use one of bg7tbl's green-pcb-face GPSDO units. I think it was somewhere around $150 or less. Check this reference thread for more information:

https://www.eevblog.com/forum/testgear/bg7tbl-gpsdo-master-reference/

Most test equipment will have a 10 MHz input and output. This way you can daisy chain your GPSDO to multiple instruments with some BNC cables. There are also units with clock distribution ports available. The clocks on GPS systems are probably the most accurate standard calibration there is. For the low cost required to take advantage of that, it is a no-brainer.

 

[RFI-EMI-GUY]

Back in the day before GPSDO s, I would zero beat the test set oscillator against WWV using a shortwave radio to receive the signal. Having an S meter on the receiver was a good way to visualize the sub hertz beat.

 

[wa8pyr]

I bought an HP8920B a few years back. It was ex Ericsson Lynchburg. Probably from a lab. Absolutely no dust inside and operates flawlessly. I would recommend one of these models for conventional FM mobile work. Be sure to get the option 102 SPECTRUM analyser and tracking generator.

Ditto, I bought a similar unit with Option 102 and it’s been a godsend. I spent another $350 for an aftermarket color LCD display which was money well spent. Calibration is spot on and it‘s clean as a pin.

Only thing for the OP to keep in mind is that if you‘re aligning radios with a service monitor like this (ie no auto-tune), you’ll need to buy or build a manufacturer-specific test box for each type radio, which breaks out the necessary signals so you can access them. I do this at home for personal radios, but at work the test set has auto-tune; I’d be aligning radios forever without auto-tune.

 

[prcguy]

You can get a useable GPSDO for under $100, I have a couple of these that work fine and for a little more you can get one with programmable output freq for about $160.

10MHz Sinwave PLL-GPSDO GPS DISCIPLINED OSCILLATOR 10M 1PPS Black Panel New # | eBay

10M OUTPUT :SINE WAVE,6dBm+-2dB. - 1 x Antenna. - Front panel:10MHz:10M sine wave output. - Rear panel:DC-IN:6.0-12.0V power input ， 5.5-2.1 socket ， inside is positive ,ouside is negative. - SIZE:WxHxD=138x25x65mm(INCLUDE BNC CONNECT).

www.ebay.com

I enjoyed the trip down memory lane.

As far as the topic at hand, depending on what you're working on, you might be able to get away with an older analog service monitor, supplemented with an SDR and software like SDR# and plugins, LTRAnalyzer, DSD+ (fastlane), PDW, SDRTrunk, etc. to decode various digital modes. Most digital radios have test modes that you can use to get the RF side of things aligned. Unless, you're going to be digging into the intricacies of the digital protocols (somehow), working on some site equipment, etc., that will get you there without breaking the bank.

As has been said, calibration is key. Having access to someone else's calibrated equipment is helpful. Anyone have experience with particular GPSDO models in the <$200 range? Is it really just a matter of plugging it into your 10 MHz external reference port and you get <0.1 ppm accuracy? Any thoughts on a budget-conscious calibration standard for RF and AF power levels?

ObClassicServiceMonitor:
View attachment 127003

 

[wa8pyr]

You can get a useable GPSDO for under $100, I have a couple of these that work fine and for a little more you can get one with programmable output freq for about $160.

I use a high-precision 10mhz crystal oscillator myself as my shop isn’t in a location friendly to GPS; for what I do it works fine.

 

[BMDaug]

It’s an oven stabilized rubidium reference or nothing!!! Actually, I don’t even have a service monitor, but I’ve been in plenty of big post production studios that use 10MHz rubidium master clocks to distribute word clock to every suite in the facility… big bucks for those!

-B

 

[prcguy]

Rubidium doesn't have to be that expensive. I put one together using an Efratom Rubidium module that was sold cheap years ago and built my own power supply and enclosure. It works fine but it also has a finite lifespan when running and I prefer using a GPSDO, especially a tiny one made in the UK by Bodnar. Its about the size of a Zippo cigarette lighter and locks up very fast.

It’s an oven stabilized rubidium reference or nothing!!! Actually, I don’t even have a service monitor, but I’ve been in plenty of big post production studios that use 10MHz rubidium master clocks to distribute word clock to every suite in the facility… big bucks for those!

-B

 

[tweiss3]

Rubidium doesn't have to be that expensive. I put one together using an Efratom Rubidium module that was sold cheap years ago and built my own power supply and enclosure. It works fine but it also has a finite lifespan when running and I prefer using a GPSDO, especially a tiny one made in the UK by Bodnar. Its about the size of a Zippo cigarette lighter and locks up very fast.

I've always wondered what was really involved to check/calibrate some bench equipment. I have a Leo Bodnar GPSDO for my 9700 that is on all the time. Never thought about its parallel use bench equipment.

 

[prcguy]

Is your Bodnar on the 40 something MHz master osc freq with the injection board or are you feeding 10MHz to the back of the radio?

I've always wondered what was really involved to check/calibrate some bench equipment. I have a Leo Bodnar GPSDO for my 9700 that is on all the time. Never thought about its parallel use bench equipment.

 

[BMDaug]

Rubidium doesn't have to be that expensive. I put one together using an Efratom Rubidium module that was sold cheap years ago and built my own power supply and enclosure. It works fine but it also has a finite lifespan when running and I prefer using a GPSDO, especially a tiny one made in the UK by Bodnar. Its about the size of a Zippo cigarette lighter and locks up very fast.

Ya, I’ve always wondered about the lifespan of those… still doesn’t stop the studios from spending $7k on one! Maybe you should start a business!! Sounds like you could corner the market!!!

-B

Antelope Audio 10MX Atomic Clock

Rubidium atomic clock perfectly suited to recording, mixing and mastering environments supporting sampling rates up to 768 kHz

vintageking.com

P.S. These, BTW, usually run 24/7! How long does something like this last running continuously? Seriously, @prcguy if a GPSDO is just as accurate, a competing product would really be something!!!

 

[prcguy]

I spent 18yrs in the broadcast industry where everything is locked to a precision 10MHz reference and the only reference I've come across in broadcast are GPS driven sources. This is for all the satellite, terrestrial TV, FM broadcast, etc, that I have worked on. When I first started in that business I purchased a rubidium standard to lock up my test equipment but it didn't get used much because of all because there was always the station GPS units I could lock to.

In my early retirement when I was doing consulting with a lot of travel I brought my cheap Chinese GPSDO with me on every job to lock up my test equipment and mostly a spectrum analyzer used for taking antenna pattern measurements. This requires very narrow RBW and long single sweep times where if the instrument drifts even 10Hz during the measurement it can ruin the test.

Ya, I’ve always wondered about the lifespan of those… still doesn’t stop the studios from spending $7k on one! Maybe you should start a business!! Sounds like you could corner the market!!!

-B

Antelope Audio 10MX Atomic Clock

Rubidium atomic clock perfectly suited to recording, mixing and mastering environments supporting sampling rates up to 768 kHz

vintageking.com

P.S. These, BTW, usually run 24/7! How long does something like this last running continuously? Seriously, @prcguy if a GPSDO is just as accurate, a competing product would really be something!!!

 

[tweiss3]

Is your Bodnar on the 40 something MHz master osc freq with the injection board or are you feeding 10MHz to the back of the radio?

Current as it is used, it's set at 49.152MHz, but the Bodnar can be set at anywhere between 400Hz and 810MHz.