[caballo]

I'm adjusting the gain on my Porta Corda MkII to match my Grados and I need two 47 kiloOhm metal film resistors to replace the existing 10 kiloOhm ones. Could someone just straight up tell me exactly what I need and where to get it? (Radioshack hopefully.)

I was going to try and do this myself (I'm assuming this should be pretty straightforward) but I'm a little confused as to which exact 47 kiloOhm metal film resistors I should buy.

This confuses me to no end:
http://www.digikey.com/scripts/dksea...S&Cat=32637808

Would it be possible to just buy the right resistors at Radio Shack? I plan on picking up a solder sucker and some desoldering braid from there anyway.

 

[diredesire]

47.5KXBK
46.4KXBK
is the digikey part number you want to get.

radioshack has:
http://www.radioshack.com/product.as...D309&hp=search
(or search for part number 271-309)

It looks like 47k ohms is not offered in metal film from rat shack
(tighter tolerances than their carbon ones).

If you don't want to wait for an order to ship, do a quick city search or google in your town for an electronics store (a real one, that has components). Pick up a few (more than 3-4) so you can closely match them with your multimeter.

If google turns up nothing the yellow pages should

EDIT: Radioshack has 47k ohm resistors: part number 271-1342 5% tolerances (not as good as the metal film 1%), but if you hand match them they might do. I read that carbon film sounds pretty warm, less analytical, although i think the difference it would make in your case would be pretty ngeligible.

http://www.radioshack.com/product.as...Fid=271%2D1342
for your convenience

 

[caballo]

Great. I'll do that. Thanks a lot!

 

[diredesire]

Quote:

Originally Posted by caballo Great. I'll do that. Thanks a lot!

Not a problem, i edited my first post for a radioshack link to 47kohm resistors if you want to get it done in a jiffy. I suggest the electronics store locally though. Solder sucker/wicks and resistors typically don't have too much of a markup. My local shop (the best one at least) sells resistors in low quantity for $.10 a piece, so it's pretty comparable to digi-key et al for small orders (which is more convenient, i dont need bulk resistors )

Edit: the 1/4w resistors i have suggested MAY not be rated high enough (in terms of wattage) for your particular amp. I would assume they are, but i just wanted to note that. If you look closely at them you can typically gauge them by size.

 

[BlazerFRS]

The only metal film resistors at radioshack come in a 'variety pack' type thing; 50 resistors of different values. Unfortunately, 47K ohm is not one of the included values, which means you'll have to look elsewhere.

I can give you part numbers at digikey if you PM me, but digikey has a minum order (if your total is less than $20 they charge you $5 extra) which is less than ideal for your situation.

Mouser (www.mouser.com) has no minimum order, but you'll pay like $6 shipping on two $.12 resistors.
Here's the part number at mouser
660-mf1/4cl4702f
these are KOA 1% Tolerance Metal film resistors.

Off hand I don't think I have any; I'll look later to see if I do, if I do I'll ship them to you at cost if you'd like.

 

[caballo]

I seem to have a Newark Electronics in my town. I'll try calling them and making sure they'd have this in stock.

 

[caballo]

I've got the local Newark guy on the phone looking for this right now:

83F1700 RN60D475K1%
VISHAY DALE
RESISTORS, METAL FILM SERIES:RN(CMF); RESISTANCE:47.5KOHM; RESISTANCE TOLERANCE:+/- 1 %; POWER RATING:0.25W; TEMPERATURE COEFFICIENT:+/-100 PPM; TERMINAL TYPE:AXIAL LEADED; MOUNTING TYPE:THROUGH HOLE; TOLERANCE +/-:1 %

RN(CMF) 47.5 kOhm 0.25 W +/-100 ppm


Edit: And now I'm learning that there's no such thing as a local Newark store. Everything comes from S. Carolina.

Well, there's got to be some local electronics store in town.

 

[caballo]

Anyone ever seen these before? I can't tell exactly if they would work for me or not.

http://www.alpha-amer.com/audiophiles/

 

[BlazerFRS]

They'd probably work, but I doubt they'd work much better than a regular resistor...

I had a thought about that radioshack metal film resistor "variety pack." It doesn't come with any 47K ohm resistors, but it does come with 5 100k ohm resistors. What you could do is solder 2 100kohm resistors in parallel; giving you 50k ohms... close enough to 47k that is PROBABLY won't matter- the gain should just be slighty higher or lower than with the 47k ohm, depening on the circuit.

Maybe someone with experience on this amp can confirm this will work?

{edit} It might take a little creativity to get 2 resistors into the spot for one, depending on the board. If it were me I'd stack them one on the other, so it's the same horizontal space, and double the vertical. Some pics of the board might let some of us help you out if you so desire.

 

[robzy]

Wow, who would have thought finding 2 47k resistors would be so hard. Best of luck! (I have three stores in melbourne austrlia where i could get them from)

Rob.