18-05-2015, 09:22 AM
Congrats - what model Hacker have you got?
In case you're not aware of it, there is a Hacker Yahoo group - http://groups.yahoo.com/group/hackerradiogroup/ - that carries most of the service manuals, along with a lot of photos, brochures, instruction books, and a database of serial numbers. Unfortunately, since Yahoo radically changed the way Groups work, it's not as easy to browse as it once was, but there is a mine of information on there.
When it comes to sourcing capacitors for old radios, I favour the axial style that closely resemble the Mullard types that were used back in those days:
Unfortunately, they have changed the style of the sleeve - until very recently they had the translucent light blue that the originals had, but now they've gone for an opaque royal blue. Still, they do look better than the modern "radial" types:
These are available from Farnell, CPC, RS, and many other suppliers. Unfortunately, most of the on-line catalogues show the old style, and for a while, if you ordered up a batch of different values you'd receive a mix of old and new styles. Last time I did that, all were in the new style. I guess it depends on the stock turnover of the supplier...
If you're getting into this game, don't just buy one or two - I always buy in multiples of 10, or perhaps more if the price breaks are favourable. You will get through them.
Because of improvements in manufacturing processes, new capacitors are smaller than old ones for a given value and voltage rating. Considerable so in many cases! So, take a look at the dimensions when ordering - if you are keen to make a sympathetic repair, you might want to choose a capacitor that is physically larger than required. But how?
Simply buy a capacitor with a higher voltage rating than the original. As Old Sparky says, as long as you are greater than or equal to the original, then no problem. Generally, always buy with a 25V or more rating because the highest voltage you're come across in a battery transistor radio is 18V. Don't mess about looking for lower voltages - unless the physical size of the replacement is greater than the original.
Some restorers use radial types, but personally, I prefer the look of the original axial types. Here are a couple of photos showing what I mean, starting with the original:
And here is a restoration using radial types. It's been done extremely well (note the sleeving on the leads) - I'm really not criticising - but as a personal preference, I'd rather go for axial types:
In Hacker sets, they used axial capacitors but often stood them up vertically. As a result, it's perhaps more "acceptable" to use radial types, but again, I stick with axial to match the original. Here are a couple of amplifiers from the RP18 Sovereign - one original and one restored:
(Actually, that's not quite fair, because those old "Daly" caps were intended to be stood up like a radial capacitor, despite being axial in construction, as the negative lead is within the outer blue sleeve. But you hopefully see what I mean)
Those Daly caps, BTW, are universally unreliable, so if you see them, replace on sight. Similar comments apply to most electrolytic capacitors - but the light blue Mullard/Philips types are actually very reliable indeed and should only be replaced if they have been positively identified as being faulty.
Hope that helps,
Mark
In case you're not aware of it, there is a Hacker Yahoo group - http://groups.yahoo.com/group/hackerradiogroup/ - that carries most of the service manuals, along with a lot of photos, brochures, instruction books, and a database of serial numbers. Unfortunately, since Yahoo radically changed the way Groups work, it's not as easy to browse as it once was, but there is a mine of information on there.
When it comes to sourcing capacitors for old radios, I favour the axial style that closely resemble the Mullard types that were used back in those days:
Unfortunately, they have changed the style of the sleeve - until very recently they had the translucent light blue that the originals had, but now they've gone for an opaque royal blue. Still, they do look better than the modern "radial" types:
These are available from Farnell, CPC, RS, and many other suppliers. Unfortunately, most of the on-line catalogues show the old style, and for a while, if you ordered up a batch of different values you'd receive a mix of old and new styles. Last time I did that, all were in the new style. I guess it depends on the stock turnover of the supplier...
If you're getting into this game, don't just buy one or two - I always buy in multiples of 10, or perhaps more if the price breaks are favourable. You will get through them.
Because of improvements in manufacturing processes, new capacitors are smaller than old ones for a given value and voltage rating. Considerable so in many cases! So, take a look at the dimensions when ordering - if you are keen to make a sympathetic repair, you might want to choose a capacitor that is physically larger than required. But how?
Simply buy a capacitor with a higher voltage rating than the original. As Old Sparky says, as long as you are greater than or equal to the original, then no problem. Generally, always buy with a 25V or more rating because the highest voltage you're come across in a battery transistor radio is 18V. Don't mess about looking for lower voltages - unless the physical size of the replacement is greater than the original.
Some restorers use radial types, but personally, I prefer the look of the original axial types. Here are a couple of photos showing what I mean, starting with the original:
And here is a restoration using radial types. It's been done extremely well (note the sleeving on the leads) - I'm really not criticising - but as a personal preference, I'd rather go for axial types:
In Hacker sets, they used axial capacitors but often stood them up vertically. As a result, it's perhaps more "acceptable" to use radial types, but again, I stick with axial to match the original. Here are a couple of amplifiers from the RP18 Sovereign - one original and one restored:
(Actually, that's not quite fair, because those old "Daly" caps were intended to be stood up like a radial capacitor, despite being axial in construction, as the negative lead is within the outer blue sleeve. But you hopefully see what I mean)
Those Daly caps, BTW, are universally unreliable, so if you see them, replace on sight. Similar comments apply to most electrolytic capacitors - but the light blue Mullard/Philips types are actually very reliable indeed and should only be replaced if they have been positively identified as being faulty.
Hope that helps,
Mark
