Repairing a Racal-Dana 9009N Modulation Meter
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- Опубликовано: 20 май 2021
- I bought a late 70s Racal-Dana AM-FM modulation meter on eBay for cheap. It did not work and was sold 'as is' so I didn't expect it to. This is the fix. It is not accurate but the alignment will be another video. Just want to get it working at this point.
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The way I do it which I guess is also not recommended is to use a current limiting DC PSU and slowly bring the voltage up on the rail to around 1A and see what start to warm up. It becomes real easy using an IR camera if you have one. Yep aging tants cause no en of problems when going short. Really enjoyed the video.
That is true. Tants are better now than they used to be but still prone to failure and that failure mode is usually shorted. I broke down a while ago and bought a Flir that attaches to my phone. It works OK but the focal distance is too long and trying to get the overlay picture to line up with the heat layer is a trick. It was a lot cheaper than a handheld unit though but someday.....
I have a current limited PSU which I use all the time in an effort to not blow stuff up.
Thanks for watching.
I picked up one of those a few years ago, I MIGHT have done a repair video on it, then didn’t use it for ages so sold it in the end.
It is OK for what it is, quick and dirty deviation meter without having to worry about frequency. It will probably just sit on top of the Cushman CE6 and get looked at twice a year but it is one more toy. He who dies with the most toys.... and all.
ARRRGH! Tantalum caps! I recently repaired an HP 4328A Milliohmmeter to use for just this sort of troubleshooting. It's a real meter meter and has ranges from 100 ohms down to 1 milliohm. I used it recently to find a bad relay contact in the 1 ohm resistance path of a Fluke 5100B Calibrator.
Nice! I don't have anything like that. The best ohm meter I have is an HP3478A which might do the job but I didn't try it.
I'm afraid the 3478A wouldn't have been of much use either. The 4328As come up on evilBay occasionally, usually without test leads (which go for crazy money). The Hirose 5-pin connector is available from Mouser and I made two test lead sets, one with Kelvin clips and one using pogo pins. It really does the job.
Thanks for the video. You can use 6 1/2 digit DMM with 4-wire kelvin leads. Something like the Capacitor Wizard works well for finding shorts too.
True. That is one thing I don't have. I have Kelvin leads but the 6 1/2 digit meter. 5 is about it.
@@AERVBlog You might experiment with your 5 1/2 digit too. Especially if it does 4-wire Kelvin measurements. If you have an ESR meter, try that too. My favorite LCR/ESR meter under $500 is the BK 880. It's the only LCR meter I have found that uses 4-wire measurement in it's price range. However, the Capacitor Wizard is very sensitive, has an analog needle display and I think works the best for finding shorts.
@@roymercer6967 thanks. I will look into it. I can do 1/10 ohm measurements with the HP. Just not used to that method.
Nice meter and great repair David! Did you post a part 2, I'm not seeing? ~Jack, VEG
No I did not. I had a heck of a time finding the right manual for this particular meter. I will try to get one out.
Tantalum caps will often (not always) discolour when they short and have been getting hot.
Yeah. I find that the blue ones hold their color better. I let this thing run drawing 1.4 amps for 10 minutes and nothing blew it melted. Funny thing was that it drew no current on DC . Strange.
I tried to find your repair of this and couldn't. Is it still up?
@@AERVBlog hmm, good question.... I just looked and cant find it either, maybe I did it as part of a live stream.... or maybe I didn't record any video at all and I am going senile.
@@TheDefpom welcome to the club. It isn't going to get any better. Sorry
Oh now I'm wondering what the big news is! I can't say I've got any better idea regarding the shorted tantalums except if you have a FLIR meter (thermal cam) of some kind, in which case you could look and see what component was heating up which normally shouldn't. I bought a small thermal cam for my android phone just for that purpose.
How does that camera work? I have looked at the Flir version for about $200.
@@AERVBlog The one I bought was the Seek Thermal CompactPRO for Android Micro USB version, they have them for Android USB-C, and iOS which I imagine is a lightning connector.
The software is a little wonky but the device does work well. It uses the smartphone (or tablet) screen as the display and has a 320x240 thermal sensor, with less than 9 Hz frame so it's not fast video but then that's not really what you buy it for. The lens is focusable and there are 3rd party lens clip ons that make for a better macro shot for circuit boards. I bought mine when it was about $290 with tax. It's now $410 plus tax on Amazon.
There's a guy that put a warning about the FLIR model on RUclips where if you don't keep it charged, it goes bad and refuses to charge. The charge light shows orange and never goes green. Apparently has happened to many people and after reaching out to FLIR about it, and they told him they'd give him a credit if he bought the gen 3 camera after having his gen 2 go bad, which would make him spend an additional $200 for the gen 3.
@@redemptusrenatus5336 thanks. That is one of those purchases I will have to think on.
Good morning, first of all congratulations, I wanted to ask how this instrument is connected to a 10/15 watt output CB radio to measure modulation? Greetings. Thank you.
You don't actually connect it to the radio. You either use a 40db pad between it and the transmitter or more simply put a short antenna on it and transmit into a dummy load located physically close to it. There is enough leakage to drive it.
@@AERVBlog Thanks, I'll do that
Next video is calibration ?
Once I figure out how. I need to build a couple of jigs for it but yes. I will do one.
@@AERVBlog tnx! I have 9008A. I think need calibration but i not have 430KHz generator ..
@@Alberto_Alletto believe it or not this cheap Chinese function generators work pretty well.
@@AERVBlog really ? do they have a spectral purity that can be used in calibrations?
@@Alberto_Alletto they are pretty clean. My FY2300S is cleaner than my old HP. I get better than .05% distortion and my HP can't do better than .1%. I was surprised too.
Come si fa per collegarlo a un trasmettitore che eroga 10 watt? Non sono troppi?
You can put an antenna like a rubber duck on the input and transmit into a dummy load or antenna. It will pick it up. Also you can use a 40 or 50 db directional coupler.
@@AERVBlog Grazie gentilissimo.👌
@@AERVBlog Last tip: do you have any links to show me to buy the directional coupler? A model, a brand? Thanks and sorry for the inconvenience. Greetings
There are a lot of them for sale on ebay. You just need to pick the one that most closely matches the values you need like frequency range and value, DB. I would recommend at least 40DB down. There is a video on my channel testing an inexpensive no-name brand from China that seems to work pretty well. If you get into the brand names you are looking at some substantial money. Hope that helps
low audio to me
Sorry.
Audio is very low, even with. Headphones
Yeah, your right. I will have to be more careful about that. Thanks.