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Old 20th Jun 2016, 6:58 pm   #1
SeanStevens
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Default Dirty Hacker RP25

This RP25 was possibly the filthiest radio I’ve found to date. It was grey! Although Hacker made it originally in blue. After a long session of cleaning (washing up liquid, hot water and lots of scrubbing) the colour returned and it was clean enough to handle without further hazard to health! Unfortunately, no ‘before’ photo was taken.

I threw in two PP9’s and was rewarded by spectacular motorboating – the likes of which I’ve never heard before. Not only was all the audio going ‘pop pop’ but there was a screaming high pitched noise to accompany it. Truly horrid.

I tested the battery voltages on load and found that one of the batteries was very low (5v), so I found a replacement. Motorboating was still all there was to hear – no matter what band chosen. After cleaning the umbilical cord connections to the amp, similar sounds, possibly a bit faster! It was time to take it to see Ian.

Oddly, FM worked when it arrived at Ian’s. No LW or MW though. There was one electrolytic capacitor standing on the RF Oscillator board (C21 – 350uF) that when tested had a very high ESR (>10 ohms) the replacement I compared it to had almost zero ESR.

It was an odd capacitor, as normally the body of the cap is negative (the can). This one however was all red and had a wire leading up the side to black section on the top. This was obviously the negative and the entire red plastic body of the can was the positive (had a little wire hanging out the bottom of the encapsulation). It was enough to confuse me – but it seems a silly mistake to have made now. Once this cap was changed the motorboat was a distant memory, however, there was nothing but hiss – no signals could be heard.

Using a sig-gen and fed into the workshop aerial a 470 kHz signal was broadcast close to the radio – this came through perfectly. Ian, being well ahead of me on the diagnostics front, suspected the main oscillator. With a little maths we added a known MW station frequency to the IF 470 KHz and got something around 1163 kHz (693 + 470kHz) With the sig-gen set to this and fed into the workshop aerial, the radio could now be tuned to a strong local MW station. So – no local oscillator!

TR1 (oscillator) was found to be a lock-fit BF194 and had no voltage on its emitter– when removed and tested on a PEAK component tester it did not appear as a component at all! Ian suggested a replacement of a different type (BF180) – this made my fragile mind spin out entirely, as it had four legs and not three. Once I’d found the E, C, B trio I had terrible trouble getting it orientated into the radio. For some reason, the board had almost all transistors marked up with E, C, B – but not TR1 – Again I got lost and had to be shepherded back into the game by Ian. There were some obvious connections from the transistor base to resistors and one to a coil; this helped me identify the orientation – again, with help. With the BF108 in the radio instantly sounded promising and once tuned to a broadcast, sounded truly marvellous. LW R4 sounded as clean as FM R4 – a trick a decent Hacker or Roberts makes look easy.

SEAN
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Old 20th Jun 2016, 7:09 pm   #2
Radiocruncher
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Default Re: Dirty Hacker RP25

Nice job Sean and a great looking set. Just wondering who the Ian is.

Graham
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Old 20th Jun 2016, 9:14 pm   #3
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Default Re: Dirty Hacker RP25

What a smart looking example you've made of it!

These are supeb performers, and as you say, sound wonderful for good old Radio 4 LW.

Was that dodgy electrolytic a "Daly"?

Nick.
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Old 21st Jun 2016, 12:12 am   #4
mhennessy
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Default Re: Dirty Hacker RP25

Probably a TCC "Elkomold" (sp?). Usually change on sight types. No idea why they kept appearing in really quite late Sovereign IIs, beyond Hacker having thousands of them to use up

Good job Sean - it looks really nice
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Old 21st Jun 2016, 5:04 am   #5
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Default Re: Dirty Hacker RP25

Quote:
Originally Posted by Radiocruncher View Post
..... Just wondering who the Ian is.
That's me.
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Old 21st Jun 2016, 8:41 am   #6
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Default Re: Dirty Hacker RP25

Quote:
That's me.
Nice one Ian and well done on the fault finding.

Graham
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Old 21st Jun 2016, 9:13 am   #7
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Default Re: Dirty Hacker RP25

I'm liking the title of this thread! Well done on the resto, any before pics?
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Old 21st Jun 2016, 9:55 am   #8
SeanStevens
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Default Re: Dirty Hacker RP25

Stupidly no 'before' pics were taken. The radio was filthy and I didn't want to touch 'it' and a digital camera with the same hands!

It might have been a DALY or TCC - it is too far down into the bin-bag now for retrieval and identification.

Nobody has mentioned that the photo of the radio attached has no handle! I had removed that so that the rexine could be glued back on......

Thanks for your kind comments and well done Ian.

SEAN
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Old 21st Jun 2016, 11:41 am   #9
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Default Re: Dirty Hacker RP25

Quote:
Originally Posted by mhennessy View Post
Probably a TCC "Elkomold" (sp?). Usually change on sight types. No idea why they kept appearing in really quite late Sovereign IIs, beyond Hacker having thousands of them to use up
Hello,

For a picture of a TCC Elkomold, see the top component in the first picture in Post 15 if this thread:

https://www.vintage-radio.net/forum/...ad.php?t=98964

Regards,

Dazzle vision
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Old 22nd Jun 2016, 5:18 am   #10
SeanStevens
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Default Re: Dirty Hacker RP25

That looks a lot like the fella!

SEAN
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Old 22nd Jun 2016, 8:33 am   #11
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Default Re: Dirty Hacker RP25

Wow! That looks brand new! Maybe in a strange way the muck had protected it!
I had one until I was persuaded to give it to my cousin, they certainly sound good.
Has your set got any (Foam?) padding under the rexine? My set seemed to be slightly padded but no where near as much as other models. I was never sure if the set was made like that or maybe the padding had degraded a bit?
There was no sign of the rexine being loose or baggy though..
Great job!

Rich.
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Old 22nd Jun 2016, 8:42 am   #12
SeanStevens
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Default Re: Dirty Hacker RP25

The photo is flattering and yes, the dirt might have kept the coating protected!

It is not as padded as some I've seen, and hasn't suffered from the baggyness that can affect the Hackers of this era. Possibly they changed the rexine supplier?

SEAN
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