FIELD INTENSITY METER CALIBRATION

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RGORJANCE
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FIELD INTENSITY METER CALIBRATION

Post by RGORJANCE »

A friend is looking for a company to calibrate a Nems Clarke Field meter. Does anyone know of a company besides Potomac that can do the work?
Tnx,
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ChuckG
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Re: FIELD INTENSITY METER CALIBRATION

Post by ChuckG »

I don't know his current status, but mooretronix used to calibrate those things.
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RGORJANCE
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Re: FIELD INTENSITY METER CALIBRATION

Post by RGORJANCE »

Tnx Chuck. I'll forward that.
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Re: FIELD INTENSITY METER CALIBRATION

Post by kkiddkkidd »

ChuckG wrote: Sun Oct 04, 2020 1:17 am I don't know his current status, but mooretronix used to calibrate those things.
And the same thing with Dan Churchill at Commercial Radio. I think that I recall him telling me that he calibrated the old FIMs but Dan may not even be involved in the business now.

Later,
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Re: FIELD INTENSITY METER CALIBRATION

Post by ChuckG »

kkiddkkidd wrote: Sun Oct 04, 2020 3:13 pm Dan may not even be involved in the business now.

Later,
Last few years it seems I never reach Dan, always someone else. Been wondering if he retired.

So...what are the requirements to calibrate these things?
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davek
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Re: FIELD INTENSITY METER CALIBRATION

Post by davek »

Voodoo, and patience? :lol:
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RGORJANCE
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Re: FIELD INTENSITY METER CALIBRATION

Post by RGORJANCE »

(Voodoo, and patience? :lol:)

He forgot to mention mirrors :lol: . Well, no luck so far. Every thing I find for calibration services are for pressure gauges.

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Re: FIELD INTENSITY METER CALIBRATION

Post by kkiddkkidd »

RGORJANCE wrote: Mon Oct 05, 2020 7:10 am
He forgot to mention mirrors :lol: . Well, no luck so far. Every thing I find for calibration services are for pressure gauges.

Fossil
But hopefully not the smoke...

Have you posted the question on the BC or RadioTech email reflector?
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Re: FIELD INTENSITY METER CALIBRATION

Post by kkiddkkidd »

ChuckG wrote: Sun Oct 04, 2020 8:54 pm
Last few years it seems I never reach Dan, always someone else. Been wondering if he retired.

So...what are the requirements to calibrate these things?
The guy that usually answers the phone is Dan's nephew or grandson (IIRC). He started out not knowing what a capacitor was but has actually gotten pretty good with their stock. I don't think that he is technical at all but the last time that I asked about Dan(probably 5 yrs ago), he was still around a few hours per day but not really involved in the day to day operation or doing much repair or calibration.
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Re: FIELD INTENSITY METER CALIBRATION

Post by kcbooboo »

The hard part is getting a "standard field" of known intensity to set the output level of the CAL OSC so the FI meter reads correctly. There are a lot of adjustments but most can be checked with a good RF sig gen and/or a step attenuator. The various manuals go through the IF stage tuning for the most part, and the main tuning and CAL OSC tuning, but carefully omit the range switch trimmer capacitors and don't mention the "zero" adjust screw on the meter.

I have three of these WX-2 and 120 meters and I can talk to you off-line if that's something you'd want to attempt yourself. My experience with these meters is they rarely need to be adjusted, which is a testament to their design and build quality. If you need something to measure monitor points, then it obviously has to be reasonably accurate, but if you also need to check for harmonics, you'd need an FIM-41 that goes up to 5 MHz, so the older 540-1600kc FIMs just aren't as valuable, not to mention difficult to power up (I use a string of seven 9V batteries in series for each 67.5V "B" battery).

Contact me via PM and we can trade email addresses if you wish to delve deeper.

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Re: FIELD INTENSITY METER CALIBRATION

Post by Deep Thought »

I built a calibration rig with induction loops to calibrate these and the FIM21/41 meters, calibrated with a FIM-41 PI had just charged me $1560 to "repair" so it had a paper trail to NIST. It worked very nicely and I was going to offer secondary calibration services (basically checking that the meter was still in spec...not necessarily making any adjustments to bring it into spec) but found there was almost no market for it and those who sent their meters in on a regular basis weren't price sensitive enough to not give Dave Harry a regular revenue stream. The ones who didn't want to deal with PI expected me to do it for under $100. Sorry, not happening.

So I documented what I had done and took it apart since it was taking up a lot of space.

If there is enough interest I might put it back together again but one $250 cal check every 5 years doesn't justify the $1500 PI cal every 2 years.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com
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