Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

I have just purchased one of these on Ebay to restore and also to compare against my HMV Diplomat as I was always under the impression that the Hacker Sovereign was the best sounding radio ever made.

Now I have a Sovereign and able to compare side by side, I'm not so sure, both sound great but the build quality of the Hacker is far above that of the HMV.

I was disappointed to note that the Hacker FM range stops at 101 Mhz which is fine if I only want to listen to BBC National stations but all of my local FM stations are in the 101 to 104 Mhz area. So is there a way of receiving these stations on my Hacker? I'm not bothered about the stations not aligning with the dial so if it means everything gets squashed a bit to the left, I can live with that but I do need to receive the local stations as well if possible?

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

I suspect the best you'll manage is to move the whole coverage of the Hacker up by 4MHz by tweaking the LO trimmer and possibly the LO coil as well. This will lose (at least) Radio 2 and probably Radio 3 off the bottom end.


To do any better you would somehow have to increase the max min ratio of the tuning capacitor swing.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

You may be able to retain R2 - it all depends on the frequency used in your area, and how high you need the radio to tune. I routinely tweak radios stopping at 104 to receive a local station on 106.8, and easily retain R2. Adjusting the oscillator trimmer to reduce the capacitive padding has significantly more effect at the HF end of the band.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

If you are brave you could try bending out slightly one of the vanes on the osc section of varible capacitor .Just the tip of the vane so giving less capacitance when fully open but the same capacitance when almost closed
I have not tried this but think it could work
Cheers Pete

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

Now thats an idea, if I did it to the out side vanes, it could work, and if not then it wouldn't be too hard to bend it back to spec again. I might try this later.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

It is much better to adjust the oscillator trimmer.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

These pictures show the FM tuning capacitor - it's not a type that lends itself to this idea, as the plates are very small, and relatively thick. Also, when fully open, there is no overlap at all, so I fail to see how bending the plates will reduce the minimum value of capacitance. In short, just don't.

Whereas adjusting the oscillator trimmer is very simple and completely reversible.

Having adjusted the oscillator trimmer (and core if needed) to get the coverage you want, it'll be worth adjusting the RF coils for maximum sensitivity - it makes quite a difference. Repeat the adjustment several times, as they interact.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

Oops, correct I had overlooked the fact that it does indeed have 2 complete separate tuners, and the FM on my model is all in a metal can so not like the photo at all which I seem to remember reading somewhere the plastic cover version was a newer version?

So in that case the oscillator must be the best option and on my tuner there are what appears to be 3 trimmers, labelled Aerial, H.F. and Oscillator, which one of these would be the best one to try out first?

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

What Paul and Mark say: oscillator!

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

..and only if neccesary peak the Aerial and HF trimmers for max. o/p at, or near the high frequency end of the revised tuning range.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

Alternatively; look out for a later Sovereign III, as the tuning scale extends to 104MHz. They (arguably) sound beter than the Sovereign II.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

There were 4 different loudspeakers fitted to the Sovereign II, and they all sound different. Meanwhile, I've found that the Peerless model fitted to the Sovereign III varies a lot from sample to sample - more so that any other type of speaker fitted to radios back then. All of that makes generalisations about sound quality rather tricky. I will say that the Peerless has rather more HF than the earlier Goodmans/Celestion units fitted to the Sovereign II, but it has a peak in the lower treble region which I find particularly annoying - perhaps it'll be less so when I'm older ;)

The OP has the original RP25 - hence the metal screen over the FM tuner - so unless it's one of the later ones just before the model changed to the A version, that'll come with a Goodmans unit. These are rather lacking in HF compared to the Celestion fitted to the later models. The version with 3 bolts on the back of the magnet usually has rather more bass than the later versions with no bolts visible.

In answer to the most recent question (post #8), the best advice is to get hold of the (excellent) service manual and have a read - it's all in there :thumbsup:

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

Wow, what a lot of very useful info, you guys are great. Actually I have discovered that I need to try and get it tuned into 107.75 as well for Radio Essex so I'll be experimenting later when I get a few minutes.

I know I have said this before, but I really love the attention to detail in the build of these Hackers, they really do seem to be built with servicing in mind with easy chassis removal, long enough wiring looms to allow the set to operated while working on it as well. It really is a far cry from the standards employed in the Diplomat, even down to having the wavechange buttons being operated directly rather than through silly cranked pieces of plastic that break and it seems impossible to get replacements for.

Why oh why do makers love mounting all sockets on the top of the radio where over the years they get full of dust and fluff and then fail? Seems almost impossible to get matching replacements these days as well.

The speaker fitted to this particular radio is the Celestion which is embossed on the speaker connection board and I have no visible bolts on the magnet assembly so I guess it is one of the later versions. Perhaps it has had a replacement fitted at some point in its life?

I purchased a service manual for this from The Military Wireless Workshop, extracted from a copy of Radio Servicing, pages 526 to 540, which while good, is still not a match for a genuine copy of the original manual as produced by Hackers I doubt.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

Just looking at the database at the Hacker Radio Yahoo group, the latest RP25 with a Celestion loudspeaker is 39539. The earliest RP25A that we have on record is 41793. So there is a reasonable overlap where Celestion speakers could have been fitted. The earliest RP25 we know about is 01063, so the vast majority of non-A models would have been fitted with the Goodmans. No bolts on either Celestion - they were only present on the Goodmans units fitted to the earlier RP25. The order went like this:

1. Goodmans with bolts
2. Goodmans sans bolts
3. Celestion with silver frame
4. Celestion with black frame (and doping compound on the surround)

The changes in loudspeakers seem fairly random with no attempt to synchronise them with a model change. And of course, loudspeakers get replaced in service. And alternatives might have been used in production because of shortages.

The Sovereign II itself had these main generations:

1. Original RP25 with germanium AM tuner
2. RP25 with silicon AM tuner
3. RP25A with revised FM tuner (with clear plastic cover)
4. RP25B with revised FM IF PCB (uses an IC)

There were several other details changes, like the addition of a DC input jack, changes in handles, etc. But overall, the model has a somewhat simpler history than the Hunter: http://www.vintage-radio.net/forum/s...d.php?p=922240

So, what is the serial number (and colour) of your RP25? And is frame of your Celestion loudspeaker silver or black? These details will help answer the question about originality, and also we could add your set to our database at the same time.

Mark

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

For 107.75 you will be moving the HF end by almost 7MHz, which is asking a lot. I think in that case you will probably lose R2. Is BBC Essex available on a different frequency, albeit with a weaker signal?

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

BBC Essex is on 95.3 , and Radio Essex is an independent station and if I leave the Hacker as it is I will loose Heart on 102.6, 103.5 is BBC Essex North, 104.4 is Chelmsford Community Radio and 107.7 Radio Essex and these are ones that I'd rather pull in then BBC Radio 2 and BBC Radio 3 if possible.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

My Hacker Hunter goes up to 101MHz, I hadn't noticed until now.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

I suspect you will be able to tune to 104.4 and keep R2 but not 107.7. It will be easy enough to experiment.

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

I attach 4 photos of the set as it is, I have done some cleaning already as it was covered in grime and paint, still some to remove but I think it will clean up a lot more yet. The leatherette on the handle is an issue but I think I can source something very similar to replace it. I can get another back grill from eBay, someone is producing new 3d printed ones.

What I need to source are a new set of earphone, gram and tape sockets along with a extension aerial socket and a replacement telescopic aerial with the knuckle joint.

The speaker as you will see is the Celestion Silver Frame one. I'm not too sure where I need to look for the serial number, the only number I have so far come across is B/25/19 printed on the tuning dial beneath the tuning knob?

The colour seems to me to be black?

Re: Hacker Sovereign II (RP25) tuning extended to 104 Mhz?
 

The serial number is stamped on the underside of the chassis. To find it, place the set face down and look up to where the tuning indicators slide. On my example here, it's near to the FM tuner. Additionally, some sets still retain their paper sticker on the turntable, but the chassis is obviously the reliable one.

The sockets can be found at Partridge Electronics: http://www.partridgeelectronics.co.uk/03Bconnectors.htm

Aerials are rather more tricky, sadly...