17-10-2023, 06:31 PM
Yes, they are quite different, but for testing you can connect either amp to either radio - the 5 pin connection is identical. The RP18 amp is larger than the RP25 one, so couldn't stay in an RP25.
And yes, although the RP25 manual says BC108, I've only ever seen the Lockfit BC148 in there, even in the earliest examples. I fit BC108s as replacements, along with a bit of green sleeving on the base, like the other transistors. As it's what the manual says, I'm fine with that!
Similar comments apply to the RP38A amplifier: https://www.vintage-radio.net/forum/atta...1276089300 (although hosted elsewhere, that set and image is mine - indeed, it's the one in my avatar)
Electrically, the RP38A is very, very similar to the RP25 amp. The earlier amp was more complicated, with many more electrolytic caps (and usually they were the blue "Daly" types that are change-on-sight). They did a good job with the A205 design. It was used in many other later sets with relatively minor changes over the years.
And yes, although the RP25 manual says BC108, I've only ever seen the Lockfit BC148 in there, even in the earliest examples. I fit BC108s as replacements, along with a bit of green sleeving on the base, like the other transistors. As it's what the manual says, I'm fine with that!
Similar comments apply to the RP38A amplifier: https://www.vintage-radio.net/forum/atta...1276089300 (although hosted elsewhere, that set and image is mine - indeed, it's the one in my avatar)
Electrically, the RP38A is very, very similar to the RP25 amp. The earlier amp was more complicated, with many more electrolytic caps (and usually they were the blue "Daly" types that are change-on-sight). They did a good job with the A205 design. It was used in many other later sets with relatively minor changes over the years.
