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Old 10th Dec 2018, 9:20 pm   #1
Panrock
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Default Hacker Sovereign II RP25B

At RWB yesterday I won a Hacker RP25B in the auction. I've always been a 'valve' man. So this is my introduction to playing with a quality transistor radio, though my mum had a similar set in the kitchen fifty years ago. It was worked hard.

Having got the set home, first impressions are encouraging and, now the plastic rear mini-grille has been secured, the set looks almost like new. I am delighted with this purchase.

I understand this set is too late to have the AF*** series transistors, so that's good. I haven't yet switched it on... because it has two rechargeable 'PP9' NiCads, both of which are completely flat. I am now attempting to charge them. I am using a charge current of 70mA per battery and I don't expect the job will be done till tomorrow evening. Let's hope these batteries are restorable. Should I be aware of any safety issues connected with the charging?

I have downloaded the service data. Fingers crossed - I'm hoping not too much work will be needed, though in a way it'll be more interesting if there is. I'll post an update here once I've switched it on.

Does 1972 sound the right year for this set?

Steve
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Old 10th Dec 2018, 9:58 pm   #2
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Default Re: Hacker Sovereign II RP25B

I thought safe charging was 10% of the battery capacity. What capacity are the batteries?
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Old 10th Dec 2018, 10:01 pm   #3
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Default Re: Hacker Sovereign II RP25B

They're 1.2AH. So this represents 6%. I understand as the charge rate goes down, so does the charging efficiency. Thus the long wait before set switch on!

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Old 10th Dec 2018, 10:04 pm   #4
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Default Re: Hacker Sovereign II RP25B

Perhaps not charge them through the night, just in case there are problems until you get experience of them.
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Old 10th Dec 2018, 10:13 pm   #5
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Default Re: Hacker Sovereign II RP25B

Frank, I will take your advice. After all, I could still try the set before the batteries are fully charged.

I am charging them in parallel from a 13.8v supply with a 27 ohm series power resistor. So far they appear happy: 8.7v across the terminals and not warming up.


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Old 10th Dec 2018, 11:06 pm   #6
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Default Re: Hacker Sovereign II RP25B

Quote:
Originally Posted by Panrock View Post

Does 1972 sound the right year for this set?

Steve
Yes, very likely: the RP72 Sovereign III replaced it in 1973, with the mains/battery -MB version following in '74. I remember being dismayed, shocked almost, by the radical change in style (well, I was 14...), but build quality held up for a time.

Paul
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Old 10th Dec 2018, 11:20 pm   #7
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Default Re: Hacker Sovereign II RP25B

We sold Hacker products but I couldn't remember dates, we sold them and apart from battery sales very rarely saw them again.
I have little knowledge of repairs, they generally didn't give any trouble. Earlier ones with the AF1XX range of transistors occasionally failed but easy to fix, not memorable.

Unlike the Roberts range and those modules.
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Old 10th Dec 2018, 11:35 pm   #8
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Default Re: Hacker Sovereign II RP25B

That's one of Hacker's better sets, Steve. And the best version of it too.

They are pretty reliable. The amplifiers give occasional trouble (the TO1 germanium transistors can suffer tin whiskers very occasionally, and the 5 pin connector is worth cleaning and tightening up), but elsewhere they are very good indeed. Sometimes the speakers develop rubbing voice coils, but I can usually fix those with a hammer and a lump of timber! RF alignment is usually a little bit out, but easily fixed.

I've lost count of the number of RP25s that I've done, but suffice to say, give me a shout if you need any advice
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Old 10th Dec 2018, 11:53 pm   #9
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Default Re: Hacker Sovereign II RP25B

There are no AF11xs inside, but there are lots of lovely Lockfits which may give trouble. Fortunately they are cheap and easy to replace if necessary.
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Old 11th Dec 2018, 9:12 am   #10
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Default Re: Hacker Sovereign II RP25B

I disconnected the two batteries from the charger overnight and have tested each one this morning. One gives loads of voltage (and current), the other very little of either.

I am not sure whether my 'parallel charging' arrangement yesterday was entirely wise, so I am now giving the weak battery a second chance at charging on its own. However, it does look likely it is duff and I shall be looking for some new PP9s. Where's the best place to find them these days?

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Old 11th Dec 2018, 9:39 am   #11
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Default Re: Hacker Sovereign II RP25B

Normal PP9’s seem to be available at a few places but it could be online orders. Rechargeable ones you probably don’t want to know about, £60+ each, there will be cheaper ones.
First , if you have a good bench supply, current limited, why not try that.

Another solution is 6AA batteries in a holder (x2), you could use alkaline or rechargeable, have to check if they will fit. Probably cheaper than PP9’s.
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Old 11th Dec 2018, 10:49 am   #12
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Default Re: Hacker Sovereign II RP25B

Hello Steve,

Nice choice of radio, you couldn't want a better transistor set.

Quote:
Originally Posted by Nuvistor View Post
Another solution is 6AA batteries in a holder (x2), you could use alkaline or rechargeable, have to check if they will fit. Probably cheaper than PP9’s.
I do this too: 6 of these in a cracked-open PP9, in a holder with a fuse and some bubblewrap, with the lid held back on with a cable tie: https://cpc.farnell.com/gp-batteries...gp%20nimh%20aa

When charged, they're good for several months of heavy use.

I charge mine from a bench supply limited to 200mA, 6 at a time in series

Nick.
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Old 11th Dec 2018, 11:44 am   #13
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Default Re: Hacker Sovereign II RP25B

Yes, I had hoped you'd approve of this Nick, just as you did of my Panasonic CRT telly (still running perfectly - never needed to touch it).

It gets better... both these rechargeable batteries are now confirmed as good. It was a very bad idea of mine to try charging them in parallel; one was feeding off the other. I'll now charge them in series over the rest of the day from a bench power supply. This is the only supply I have that can muster sufficient voltage, so it won't also be available to test power the set.

Switch on this evening!

Steve
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Old 11th Dec 2018, 3:19 pm   #14
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Default Re: Hacker Sovereign II RP25B

Good news that the batteries woke up!
I noticed these rechargeable batteries when I looked at the set myself.

It might be a good idea to charge them separately though as series charging can bring on problems if their internal resistance is not matched, this could then seriously "over volt" the other battery.

Cheers
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Old 11th Dec 2018, 5:35 pm   #15
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Default Re: Hacker Sovereign II RP25B

I have several Hackers and have made PP9 substitutes from packs of AA alkaline cells wired to PP9 battery connectors. My local Home Bargains store sells 20 packs of AA alkaline cells (JCB brand) for £3. That's £1.80 for a set of batteries compared to a tenner for two PP9s bought from the Internet. I secure them with Blu Tack to stop them rattling around inside the cabinet. Of course the radio can still be used with PP9s if required. I am new to Hacker radios too and am very impressed with their RF performance and good quality sound.

Regards
Martin
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Old 11th Dec 2018, 5:44 pm   #16
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Default Re: Hacker Sovereign II RP25B

The only radio I found disappointing from Hacker was the Helmsman, LW, MW and lots of short wavebands.
LW and MW were fine with the usual good quality audio, the SW Bands I was a bit underwhelmed with. We didn’t sell many, one customer bought one and he also bought mail order a Russian Radio with lots of SW bands. The Russian one received stations clearly that the Helmsman didn’t know were there.
The Helmsman was working correctly, tried another to be sure.
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Old 11th Dec 2018, 5:56 pm   #17
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Default Re: Hacker Sovereign II RP25B

Quote:
Originally Posted by Nuvistor View Post
The only radio I found disappointing from Hacker was the Helmsman, LW, MW and lots of short wavebands.
Just two really, 11 to 25m bands covered in SW1 and 31 to 60m SW2, plus SW3 which was an extended "marine band ", 75m to 200m or so. Sensitivity not among the best and hopeless for logging stations: the Super Sovereign's two SW bands weren't much better though the aerial tuning control of the -MB model improved matters quite a bit. To be fair the £9. 19s. 6d "Russian miracles" (from Latvia) were a better proposition for SW broadcast listening than pretty much any sub-£50 British domestic radio.
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Old 11th Dec 2018, 7:56 pm   #18
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Default Re: Hacker Sovereign II RP25B

The two batteries' voltages balanced nicely during charge, with each showing 9.8v directly after removal from charge, going down to 9.6v after leaving them for ten minutes. Anyway, I put them in...

I wasn't disappointed! The set was stable and the sound was literally fabulous. Even medium wave sounded hifi. I've never owned a transistor radio like this before.

I was glad to see Classic FM was easily reached at the top end of the band.

There was a little rustle from the tuning capacitor at first. This was cleared by working it back and forth down the band. No crackles whatsoever from the other controls though.

Two things will need attention. Firstly, the tuning calibration is displaced toward the HF end - on all bands - and so the pointer disappears off the left end further than it should. Therefore it looks like an adjustment to the stringing will be required (though I haven't looked inside and checked whether this set actually has stringing yet!). Maybe I'll also check the alignment at the same time.

Secondly, the inter-station muting button doesn't do anything, when selected. All advice welcome. I suppose this might be nothing other than a switch oxidised from lack of use.

And that seems to be about that. The word "chuffed" sums up my feeling about this purchase - all this, including rechargeable batteries, for fifteen quid.

One other thing: is some trim missing from the handle or were they all like that?

Steve
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Old 11th Dec 2018, 8:06 pm   #19
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Default Re: Hacker Sovereign II RP25B

Yes the trim is missing, the interstation muting, I think there is an adjustment but it could be just a dirty switch.
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Old 11th Dec 2018, 8:52 pm   #20
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Default Re: Hacker Sovereign II RP25B

Yes, the pointer datum is the first thing to check. You can normally correct it by moving "pulley B" along in the slot provided. The instructions in the (excellent) manual tell you to set it so that the pointer just reaches the right hand end of the scale openings.

Frank is correct about the adjustment - it's on the FM IF PCB, which is on the left as you view the set from the rear. It also enables AFC when pressed.

This reminds me that I did once have a fault with this once. IIRC, I eventually found a faulty diode inside L1. That took some finding

I would check the quiescent current, which should be around 22mA when switched to FM. Any higher and it'll be worth checking the adjustments on the audio PCB.

Glad you're pleased with it - they really are lovely sets. Next, you need a Hunter RP38A, which sounds even better
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