[volt-nuts] Fluke 720a self calibration repair
rob.klein at smalldesign.nl
Sun Sep 27 15:42:25 EDT 2015
How many of those pots do you need? I've had the innards of an 88(something) lying around for ages and your welcome to a few, if you're willing to pay shipping from the Netherlands. With only the trimmers in a small box, that should not break the bank.
Met vriendelijke groet,
Verstuurd vanaf mijn tablet
Dave M <dgminala at mediacombb.net>schreef:
>I tried to find this style trimmer pot with a wirewound resistance element,
>but found that all I could find was the Cermet type. It appears that
>wirewound pots have all been replaced by Cermet. the wirewound pots had a 1W
>power rating, whereas the Cermet pots arte only rated at 3/4W. In the 720A,
>the reduced power rating won't be an issue, but in some vintage equipment,
>it might be.
>I've also tried, to no avail, to find a source for the metal-cased wirewound
>trimmer pots used on the K-V divider in some older Fluke differential
>voltmeters, such as the models 883A, 885A and 887A. Does anyone know of a
>source for replacements for those pots? I have an 887A on the shelf that
>I'd like to get back to original condition if I could find a couple of that
>style trimmer pot. They're only 2 ohms, making the search even more
>difficult. At this point, my only recourse is to find a defunct donor unit
>at reasonable cost, and salvage the parts. Does anyone have a hangar queen
>that I could get for shipping charges? I'd be really happy to get mine back
>on the road to health.
>> Apologies - my mistake - I wasn't paying sufficient attention when
>> Google decided that this was a perfect match when searching for
>> But £180.27 each whereas Newark, the US arm of Farnell only want $120
>> or approx £80 for the same part! Are there really that many Brits who
>> put up with being ripped-off to these levels?
>> Tony H
>> On 26/09/2015 01:27, Charles Steinmetz wrote:
>>> Charles wrote:
>>>>> I had to look it up. The company was Arrow (800 833 3557). The pots
>>>>> were manufactured by Bournes with a manufacturer part number of
>>>>> 300SP-1-502. Unit cost $7.73 in 2011. I bought 26 so my cost was
>>>>> about $200. I wanted a "Manufactured in America" part but can't
>>>>> remember if that was too pricey or not.
>>> Tony wrote:
>>>> They are now $92.55 from Arrow now and Farnell want over $200 each
>>>> if you buy 25 or more!!!! There don't seem to be any obvious cheap
>>>> alternatives for 10 turn 20ppm/C 5W pots.
>>> The original pots were Bunker Ramo-Eltra (later, Bunker
>>> Ramo-Amphenol) P/N 3800P-502. These were 20-turn, 5k, 10%, 1W,
>>> +/-50 ppm/C wirewound parts in the 34b rectangular package. The
>>> Bourns 3005P-1-502 matches these specifications (I suspect "300SP"
>>> in Charles's message was a typo). I do not know if the pin layout
>>> is the same as the 3800P-502. Verical has the lowest price on the
>>> 3005P-1-502 that I could find in a quick search, $7.68 each. Others
>>> charge from $9 to $14. Tony -- what part number were you quoting specs
>>> and prices for? I
>>> found nothing searching for "300SP-1-502."
>>> Best regards,
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