Hi David,

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.

Charlie

On 9/25/2015 9:45 AM, David Garrido 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.

Do they need to be 5W? Is that to minimize self heating?

The TT Electronics 7286 series are 10 turn, 2W, 20ppm/C, but only $10.66
for 25+. Or you could use 2 10K ohm 7270 series in parallel at $8.45
each for 50+ if you could fit them in somehow!

On 25/09/2015 20:10, Charles Black wrote:

Charles wrote:

Tony wrote:

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,

Charles

Apologies - my mistake - I wasn't paying sufficient attention when
Google decided that this was a perfect match when searching for 300SP-1-502:

http://uk.farnell.com/webapp/wcs/stores/servlet/Search?st=3400s&catalogId=15001&categoryId=700000005471&langId=44&storeId=10151

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:

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wirewound pots have all been replaced by Cermet.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.

Cheers,
Dave M

Tony wrote:

Tony,
I'm a US citizen, but I do know that the UK has a 20% VAT on each level of
manufacture and/or distribution. That can add up quickly in the end
purchase price.
Or am I missing something here?

No VAT in the US....not yet anyway;-)

On Sun, Sep 27, 2015 at 2:15 PM, Tony vnuts@toneh.demon.co.uk wrote:

That's not quite how VAT works.  If I buy a widget with a notional value of a pound, I pay £1.20.  If I am registered for VAT (typically the case for most businesses), I can then sell it on at £2 plus tax (IOW £2.40), I offset the input tax (20p) against the output tax (40p) and end up owing the govt. 20p.

Cheers, Dave

Stan,

The Farnell prices don't include the 20% VAT. We get used to 1:1 £/$
exchange rates but Farnell often seem to charge >= double the Newark
prices. Unfortunately ordering from Newark doesn't always help because
you then get hit with expensive shipping costs and the outrageous, and
seemingly random, customs handling fees by the courier.

Tony H

On 27/09/2015 22:56, Stan Katz wrote: