Hacker RP 25 -Motorboating now now AM and high quiescent current

[Murphyv310]

True Lawrence, that I do agree with.
I have to say though that some of the wrangling I've seen makes me cringe. We all know there is often more than one way to tackle a repair. Some assume you'll do it one way, another a different approach, they all if done correctly will get the same result...... a working set. Where it goes wrong is when a person in all innocence suggests doing a different way to the previous poster. It may not be wrong and also have no errors but it's a different approach that you or me may take.
No experienced engineer that has been in the service industry for the majority of their lives is likely to give bum information, they might make a human error but surely not intentionally.
It's one reason that I feel it's best for one or two helping rather than we all chip away and confuse the beginner, even when someone says, try this first before you try what Fred says.

Just my thoughts.

Firstly though we at least need a circuit diagram and layout.

[Bonky]

The whole manual is here:
https://groups.yahoo.com/neo/groups/hack...roup/files

(members only)

If anyone wishes to send me a pm (rtjstevens(at)me.com) perhaps if the group's owner has no objection then perhaps I can send the whole manual as a PDF.

BW

Richard

[Crackle]

Its all in the radio Museum, https://www.radiomuseum.org/r/hacker_sov...5rp_2.html
It is well worth joining and helping to make it the best source of information on radios.
I joined, all you need to do is upload some photos of your radios.
Mike

[Bonky]

Yes, it doesn't look like it'll do AM. Keep an eye on the "for sale" forums, as they come up often enough for sensible money. It might be worth a "wanted" ad - and that's an example of a thread that is worth running on UKVRRR as well as here.

What other test gear have you got?

I'd welcome any preferred makes and models please...

Thanks,

Richard

[Mark Hennessy]

Using either the sig gen or the tracer I can get a sound form the C and E of T4 and the C of T3 (only).

That's progress! And it shows that the diode is almost certainly OK.

So, what if you try to inject the signal into the base of T3?

I'm obviously stretching the patience of some by posting on various forums. I'll stop this and only post if something 'meaningful' happens.

Of all the forums I've been on the 'old radios' ones seem the most polite, helpful and well-written (you should try model

Please don't worry - you're not causing any problems. Now that we've slowed things down nicely, we're in a position to apply logic, calmly and methodically. That's the ticket

Yes, by and large we're a friendly bunch. Life's too short for anything else, frankly

[Bonky]

Thanks!
"So, what if you try to inject the signal into the base of T3?"

No sound I'm afraid.

BW

Richard

[Mark Hennessy]

OK, so it seems like there might be a problem with T3. It might be the transistor itself, or it might be something else in the vicinity. It's late now, so I'll reply more fully tomorrow...

Oh, and a correction. Earlier I said 455kHz, but should have said 470kHz. Later sets used 455kHz. But if you're using the Velleman signal tracer (K7000?), then that probably makes little difference at this stage.

[Murphyv310]

Hi.
I now have the diagram and will study it tomorrow.

[Bonky]

I have replaced T3 (an AF178 with a very low hFE) with one of the original AF 114 (with a high hFE). Voltages (relative to 8.22V on the HT rail)are: B:6.8V. E: 7.3V on T3)

Injecting a 1kHz or 470kHz(non-modulated sine wave) into the bases go all the transistors yields no corresponding sound.

I played with touching the ends of a new diode over the PCB tracks where I assumed the original detector diode was situated...no sound (and, yes, I did turn it around).

Let me know when I am becoming an unbearable nuisance...

Thanks,

Richard.

[Murphyv310]

Hi.
Richard without modulation you wont get any audio.
A couple of questions without prompting you. What frequency have you set your signal generator to?
Also what level is that signal set to.
Once you have replied I'll get back to you.

Incidentally I'm not on the PC all day, I look in now and again though and will reply ASAP.