Finally got my AR3a Recapped

[RoyC]

When AR went to conventional sand-cast resistors what did they use?

-Kent

Hi Kent,

AR went to a small 7 watt sandcast resistor. I don't remember if it is .5 or .51, but the difference is insignificant given the typical tolerance specs of resistors of this type...not to mention the fact that this resistor is in series with the midrange pot's variable 0 to 15+/- ohm series leg.

In the later AR-3a Limited the resistor is a .5 ohm, 22 watt sandcast.

Roy

[JKent]

AR went to a small 7 watt sandcast resistor. I don't remember if it is .5 or .51, but the difference is insignificant given the typical tolerance specs of resistors of this type...not to mention the fact that this resistor is in series with the midrange pot's variable 0 to 15+/- ohm series leg.

Ah! Much better. Mouser has 0.5 Ohm 10w 10% sandcast wirewound resistors for 39 cents. Or if you want to spring for 5% they have the ones in the fancy ribbed aluminum shells for $2.09. Or if someone's putting together a PE order I'm sure the 0.47 ohm is close enough.

Thanks.

-Kent

[RoyC]

Ah! Much better. Mouser has 0.5 Ohm 10w 10% sandcast wirewound resistors for 39 cents. Or if you want to spring for 5% they have the ones in the fancy ribbed aluminum shells for $2.09. Or if someone's putting together a PE order I'm sure the 0.47 ohm is close enough.

Thanks.

-Kent

Kent,

Your use of (2)10 watt 1 ohm resistors to make a .5 ohm resistor actually increased the power handling rating to 20 watts. I think that is a good approach.

Parts Express has a nice .51 resistor with a 2% tolerance rating:

http://www.parts-express.com/cat/audio-grade-non-inductive-resistors/301?N=19850+4294967118+4294962679&Ne=10166&Nrs=collection%28%29%2Frecord[endeca%3Amatches%28.%2C%22P_PortalID%22%2C%221%22%29+and+endeca%3Amatches%28.%2C%22P_Searchable%22%2C%221%22%29]&PortalID=1

Roy