The Secrets Behind the 91-12F Boonton Probe
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- Опубліковано 6 жов 2024
- What is it with the probes for the Boonton RF Millivolt meters. They cost more than the meter itself and getting one won't make the meter work right anyway. I take you through the way they are built and what can be done to make one work, mostly and go through the readings I got on my meter after doing the best I could to match one to it.
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hi, a very very informative video I must say. I'm after one of this meters myself but do not know where to get it with the probe as on eBay I could only find meters on their own and found a probe in the UK Where I live at a hefty 103 Sterlings only to stumble across your video and then realized that it won't work.......Woaww...thats just crazy. The only reason I really need this meter is that I've purchased a Boonton 102F signal generator that is faulty and in the service manual a lot of measuring points need to be done using this very meter (Model 92B). cannot find anyone willing to help with fixing this generator so....I'm trying to fix it myself.
Good luck with the generator. Remember that any Booton probe will work it just won't be accurate so if all you need is relative readings go for it. Thanks for watching.
I got a 92B in the UK last year for £77 it came with a matching probe and 50ohm adapter plus the 100:1 divider, just needed to change a couple of capacitors and all is good!
Great job! Finding these things with probes is tough. Do the serial numbers on the probe and unit actually match?
@@AERVBlog Yes, everything has matching numbers, spotted it on Ebay and snapped it up, i had been using a DIY RF probe with my DVM but nothing like watching a meter needle swing :)
@@phildavies5833 very nice. I am jealous. Thanks for letting us know that there is a chance we could get one too. :-)
I agree with all your comments, it's sad that Greed motivates people to do what they do
Yeah. Greed is prevalent. Never got the bug myself and my bank account can prove it. Thanks for watching.
Hello sir, great demonstration, I also have the same millivoltmeter I am looking to make the test point, can you send me the measurements of the part Regards
Please contact me at aervblog@gmail.com
@@AERVBlog Hello Sir, I sent you an email, thank you for responding to me.Regards
Hi Sir thanks for sharing your experience.
I bought a 92B here in EU for 70 and got the probe but is not matching, in fact like yours has not even a number on it.
Went through an entire calibration process and seem to read accurate, of course to a certain degree, I’m not a cal lab.
But I have another type of problem with it. When a “strong” signal (higher than 100mV) is measured, then switching back to most sensitive scale the needle doesn’t go back to zero. It takes some time to settle back. Manual says that this overload is possible to occur when you go back to 1mV scale but should take less then a minute to recover. Mine can take hours. The higher the signal the more pronounced this effect.
Any idea where to look?
Thanks
I would check all the electrolytic caps. One or more of them might have changed value drastically. Also check any resistors that would bleed off the voltage. Do you have a schematic?
@@AERVBlog I do have the manual and the schematic. Found it on internet. Actually I have found two different manuals for the B version and one of those is reflecting my unit. Small changes anyway. Thanks for your advise. I will list all the sprague electolitics inside and substitute them then I’ll see from there. The mechanical chopper also is quite delicate I guess. Overall I like the instrument and used an unused secondary out of the transformer to light the movement with 3 incandescent bulbs old style :).
Furthhermore I have opened the movement to clean the acrilic inside. Very dangerous but now its nice and clean.
I really wish to solve that overload issue to put it back to work.
@@IZ0MTW you might want to look into getting the electronic chopper upgrade. Not nearly as finicky.
Sir what is the specific usage of this meter bcoz I got the probe alone with probe what else can be done
The meter measures low RF levels down to less than 1mV. Very useful when tracing circuits and aligning radios. The probe has to match the specific unit by serial number or it will not be accurate. You can not do much with the probe alone. It is not like a diode detector probe.
the hp3406a is a much more advanced an accurate meter,with some added unique features .And the probe is permanently attached!
That is true. I am sorry I got this thing but at least now it does give relative readings. Thanks for watching.
AERVBlog
I know how you feel! The same thing happened to me !
I bought an analog version of your meter on eBay, without the probe.
So i built my own probe, but the accuracy is very poor.A guy named Stephan Novotill has studied various RF probes for these meters and did a write-up you can find on the 'net.
A few months later i bought an hp-3406a!!!But you seem to have the problem licked!
I might take another look at mine! Thanks for the excellent info. 73 de PZ1CD.