what resistor rating is preferable? - UK Vintage Radio Repair and Restoration Discussion Forum

cendoubleu · 17th May 2010, 8:54 pm

Hello folks. I'm in a mind to get in a stock of components so that if a particular project I see takes my fancy I can get stuck in fairly quickly. I already have an excellent stock of capacitors at valve-voltage ratings but not so resistors, most being of 1/4 rating for SS projects. What would be the recommendation for a resistor stock? Would it be 1/2w or 1w? And do modern resistors have the correct voltage rating even at the higher wattage values?
Thanks in anticipation, Charlie

evingar · 17th May 2010, 9:15 pm

I would recommend 3 Watt Metal Oxide types :-

http://uk.rs-online.com/web/search/s...duct&R=2143042

dave cox · 21st Jun 2010, 2:12 pm

These look good to me, and they maybe a little cheaper than RS :

http://www.rapidonline.com/Electroni...66471#techspec

I've found their re-stocking isn't as good as RS though, I've waited months for some 12pF NPO ceramic caps ...

dave

David G4EBT · 21st Jun 2010, 3:11 pm

Rather a pity that their 3 Watt metal oxide range only goes up to 56k

A bit low for many of our requirements.

As with most firms, there's a P&P charge for small orders.

In Rapid's case, £4.95 on orders below £30. Hence, even if you only want £25 in goods, you might as well order another fiver's worth and get free P&P. (It makes little sense to order say £10 worth of items, as the P&P would amount to a 50% uplift).

No criticism of Rapid or any other firm which adopts this policy - they have a living to make and it costs as much to process a small order as a large one, with little or no profit in it for them.

As to a range of resistors to stock, I've often considered this, but the range used on different receivers seem to be so infinitely variable, that it's not quite as simple as stocking say 0.1 and 0.01 uF caps to replace waxies.

The 3 Watt metal oxide resistors look the part in older sets, being similar in physical size to the old 0.5 Watt and 1 Watt carbon types, whereas modern 0.5 and 1 Watt ones are so small that they look out of place.

I've tended to build up my stock over time by ordering 5 or ten of whatever values I need for a particular set, figuring that in time, other sets will need at least a few of those values.

I tend only to replace resistors which are more than 20% out of spec, as 20% was often the original tolerance anyway when the radios came off the line.

I guess that if someone did a bit of research, a range of commonly occurring resistors might arise, but I've never bothered looking further into that.

David.

matthewhouse · 22nd Jun 2010, 7:06 pm

Just radios in Canada sell large kits of valve equipment suitable resistors in 1,2 and 3W. Shipping is very fast and I would recommend them to anyone. They sell on eBay here.

M0FYA Andy · 22nd Jun 2010, 7:35 pm

I can only second the recommendation of JustRadios - I bought one of their capacitor kits and was very pleased.

Andy

brianc · 22nd Jun 2010, 10:47 pm

I bought a couple of their resistor packs - 1W and 2W. The 2Ws are better as they are that bit larger but the 1Ws don't look too out of place among '40s and '50s 1/4W components. They are excellent value for money and as Mathewhouse says, shipping is very fast.

17th May 2010, 8:54 pm	#1
cendoubleu Tetrode Join Date: Jan 2007 Location: Lincoln, Lincs. UK. Posts: 94	what resistor rating is preferable? Hello folks. I'm in a mind to get in a stock of components so that if a particular project I see takes my fancy I can get stuck in fairly quickly. I already have an excellent stock of capacitors at valve-voltage ratings but not so resistors, most being of 1/4 rating for SS projects. What would be the recommendation for a resistor stock? Would it be 1/2w or 1w? And do modern resistors have the correct voltage rating even at the higher wattage values? Thanks in anticipation, Charlie

17th May 2010, 9:15 pm	#2
evingar Octode Join Date: Oct 2003 Location: Newbury, Berkshire, UK. Posts: 1,770	Re: what resistor rating is preferable? I would recommend 3 Watt Metal Oxide types :- http://uk.rs-online.com/web/search/s...duct&R=2143042 __________________ Chris

21st Jun 2010, 2:12 pm	#3
dave cox Nonode Join Date: Jan 2009 Location: Bristol, UK. Posts: 2,062	Re: what resistor rating is preferable? These look good to me, and they maybe a little cheaper than RS : http://www.rapidonline.com/Electroni...66471#techspec I've found their re-stocking isn't as good as RS though, I've waited months for some 12pF NPO ceramic caps ... dave

21st Jun 2010, 3:11 pm	#4
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: what resistor rating is preferable? Rather a pity that their 3 Watt metal oxide range only goes up to 56k A bit low for many of our requirements. As with most firms, there's a P&P charge for small orders. In Rapid's case, £4.95 on orders below £30. Hence, even if you only want £25 in goods, you might as well order another fiver's worth and get free P&P. (It makes little sense to order say £10 worth of items, as the P&P would amount to a 50% uplift). No criticism of Rapid or any other firm which adopts this policy - they have a living to make and it costs as much to process a small order as a large one, with little or no profit in it for them. As to a range of resistors to stock, I've often considered this, but the range used on different receivers seem to be so infinitely variable, that it's not quite as simple as stocking say 0.1 and 0.01 uF caps to replace waxies. The 3 Watt metal oxide resistors look the part in older sets, being similar in physical size to the old 0.5 Watt and 1 Watt carbon types, whereas modern 0.5 and 1 Watt ones are so small that they look out of place. I've tended to build up my stock over time by ordering 5 or ten of whatever values I need for a particular set, figuring that in time, other sets will need at least a few of those values. I tend only to replace resistors which are more than 20% out of spec, as 20% was often the original tolerance anyway when the radios came off the line. I guess that if someone did a bit of research, a range of commonly occurring resistors might arise, but I've never bothered looking further into that. David. Last edited by Station X; 21st Jun 2010 at 4:35 pm. Reason: Full quote of previous post removed.

22nd Jun 2010, 7:06 pm	#5
matthewhouse Octode Join Date: Jul 2006 Location: Willand, Devon, UK. Posts: 1,023	Re: what resistor rating is preferable? Just radios in Canada sell large kits of valve equipment suitable resistors in 1,2 and 3W. Shipping is very fast and I would recommend them to anyone. They sell on eBay here.

22nd Jun 2010, 7:35 pm	#6
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: what resistor rating is preferable? I can only second the recommendation of JustRadios - I bought one of their capacitor kits and was very pleased. Andy

22nd Jun 2010, 10:47 pm	#7
brianc Rest in Peace Join Date: Jun 2004 Location: Burghfield, Reading, Berkshire, UK, Posts: 1,055	Re: what resistor rating is preferable? I bought a couple of their resistor packs - 1W and 2W. The 2Ws are better as they are that bit larger but the 1Ws don't look too out of place among '40s and '50s 1/4W components. They are excellent value for money and as Mathewhouse says, shipping is very fast.