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Old 27th May 2023, 5:18 pm   #1
EF80TVVALVE
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Default His Masters Voice Fluid Light Five 442

Hi everyone,

I picked up this HMV 442 from this year's retrotech, its a radio that's been on the list for a long time but I've never actually done much to try and obtain one. I seen this one on a stall and thought it the perfect opportunity to finally acquire one.

This particular example has been worked on in the past, obviously somebody knew what they were doing as the Pea Exe For has been replaced with a PEN4VA and the radio looks to have had restoration, some more recent and some look to be much more ancient repairs. Thankfully it looks like they've also re-stuffed the large metal box of capacitors that hides under the tag strip on the underside, something that is quite a large undertaking on such a set.

The first task was to work out where all of the speaker leads actually connected to on the transformer. They were all removed from the tag strip when I purchased it leading me to believe that there may be a fault with the radio. I soon discovered that the tuning drive cord from the knob to variable condenser had snapped. With both of these jobs sorted and the radio finally back together I slowly brought it up and found that it worked in a fashion.

The main faults are that the radio is incredibly deaf so I'm sure an alignment is in order but first I'll go over the circuitry and make sure there aren't any resistors gone high or other faults that would cause this. Secondly the gram setting isn't working quite right and it only gives me a weak distorted output when connected to my 78 turntable with a HMV type 25 pick up. Funnily enough it does work when the knob is slightly between the gram setting and it's neighbour setting leading me to believe that one of the cam lobes could be damaged or misaligned.

Also the back cover and wood panel are missing, I wouldn't suppose any forum members have any of these hanging around?

With all being well and if it responds well to more work I will consider reversing the work done on the output circuitry and replacing the valve with the correct type. I know it will likely cost more than the set is worth but it would be nice to return it as it should be.

It would also be interesting to know if anybody recognises this set? As it looks to be collector owned in the past it would be nice to know some history if it looks familiar to anyone!
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Old 27th May 2023, 10:57 pm   #2
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Default Re: His Masters Voice Fluid Light Five 442

I bet the person who did that to this radio has seen this thread and is keeping their head down

I used to get really annoyed about folk making money out of robbing power triode output valves from classic radios - the old biblical story of Judas and the thirty pieces of silver always seemed to spring to mind!

I've lately started to think a bit differently. I'm still against people removing these triodes, but there's another school of thought that once an original valve has been replaced with something less desirable and the appropriate modifications have been done to make the set perform as well as it did originally, then the the future of the set is more secure in that it won't have its output valve removed and the rest just broken up or scrapped, as has happend to many, unfortunately.
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Old 28th May 2023, 12:27 pm   #3
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Default Re: His Masters Voice Fluid Light Five 442

Hi Techman,

Yes it's a shame many of these sets have been lost all because of that one valve. I think this example has been nicely saved and you never know the reasons why the valve was removed in the first place. I suppose it could be possible that the original valve was faulty and the price of replacement deemed too high, or it could already have been robbed when the restorer took the set on. Either way someone has gone through some effort to see that a suitable replacement was fitted and the PEN4VA seems to work very well with only little modification.

Like I say, I may put it back right but it all depends on how much I love the final results once it's had a service. It'll be staying here with me so I know that I won't rob it of the valve once replaced and if it ever comes to moving it on I'd hope that through the forum another safe home could be found.

It looks to be quite an advanced set for the time, I wonder where abouts it stood in the market? I'd presume at the higher end. Not the neatest of EMI receivers internally but then again most of their sets from this era are a little like a rats nest underneath.
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Old 29th May 2023, 7:56 pm   #4
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Default Re: His Masters Voice Fluid Light Five 442

I have the HMV 443 model (identical chassis, just cabinet cosmetic differences). These sets give an extremely good account of themselves with both excellent H.F. & L.F. audio quality. I see you mentioned about it will need alignment. The I.F.T's in this model are stagger tuned to get a decent I.F. passband, therefore, you will need a "Wobbulator" and "Oscilloscope" to set the I.F. passband correctly. The I.F. strip should be near enough correct (unless someone has adjusted the settings). I have never touched the I.F. adjustments on mine and mine performs beautifully. Mine also has the correct output valve - fortunately.

This chassis has the unusual feature of having POSITIVE feedback from the output to the tone compensation circuit input, via a feedback control trimmer - on the back panel of the chassis just below the output valve - to emphasise the top notes. The stage will oscillate if the trimmer is advanced too far, (with front tone control at minimum).

If you have the connections to the output Transformer primary reversed you should still get an output, but it may be weaker, as there would now be Negative feedback to the input tone correction circuit (instead of positive feedback) and therefore no 'top-note' boosting.

Good luck with the restoration work....
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Old 1st Jun 2023, 4:08 pm   #5
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Default Re: His Masters Voice Fluid Light Five 442

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Originally Posted by EF80TVVALVE View Post
if it ever comes to moving it on I'd hope that through the forum another safe home could be found.

It looks to be quite an advanced set for the time,
Well you'd hope so, but I've known of several members that have been doing this sort of thing in plundering output triodes and selling them on in the past - there's probably others that I haven't spotted, as I don't go looking for this sort of thing, it's just an observation and the fact of happening to be looking in the right places at the right times - it's not exactly a crime and they can do with their own radios what they like, I suppose, it's just 'asset stripping' - and I won't be mentioning any names!

It is quite an advanced set for its time - 1934, I think. Many sets were still TRF types at around this time.

That PEN replacement output valve isn't one I'm particularly familiar with, it didn't ring any bells with me, so probably haven't got one in my stash, although I haven't checked. The only thing that I can see against it is that its heater current is a bit higher than the original, being as it's indirectly heated, although only by the amount that an extra dial lamp would use.

I see that valve was produced in both B5 with side terminal and B7, I can't see the side contact, so it could be round the back or it's a B7 - I wonder which has been used?

Just thinking about it, you could use the B5 version without even having to change the base. You could be a bit of a butcher (to the valve, not the radio) and chop off most of the fifth (centre) pin of the valve and solder a connection from the stub of this cathode pin to one of the heater pins - you'd have to be careful, as the wire from the pinch goes all the way down through the pin to be soldered only at the bottom, so if you were careful to only cut the outer pin, you could use the wire from the pinch itself, bent round and soldered to the other pin. Then you could take a wire from the side contact screen connection and solder it to the anode pin to triode strap it and it would then be virtually plug and play. You'd have to check the anode current and make circuit adjustments if necessary. There'll be a hum bucker for the old directly heated valve below the chassis, whether this'll need any adjustment or alteration, I don't know, it's not something I've ever done, although I've seen it discussed in the past when 'triode' output valves have been removed for resale. Others may have their own ideas regarding what I've just described - it's only my own thoughts.

I personally would just leave the set as it is and only put it back to original triode output operation if you happen to come by one at a knock down price in your travels.
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Old 2nd Jun 2023, 9:50 am   #6
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Default Re: His Masters Voice Fluid Light Five 442

Mister Valve, I do hope it doesn't require much work to improve the sensitivity. Hopefully this weekend I can do a little more investigation and see if there's any components that require replacement. There are still a number of original resistors in the set and I've found these types to be either very close to spec of to have drifted quite badly. I'm also hoping to repair my outdoor aerial which should improve things but even with the length I had patched up I'd have expected better results from the 442. I have a Marconi manual for the same chassis and it's a whopping 16 pages, quite something for a valve radio but the details contained are very thorough.

Techman, yes it's a shame but unfortunately it happens. Mind you, I've seen some incredibly rare and museum worthy items stripped for amplifiers, valves etc mainly for the far east market but I won't go into much detail on here as I don't want to turn this thread into a discussion on that matter, I'm sure most of us on here share the same opinions on that.

The valve used is a B7 version and whoever has undertaken the conversion has done a really good job of fitting the base and wiring it all up, they've certainly done it with care and not as a quick bodge so I'm happy to leave it as-is if it comes to it. If I were to replace for the original type then I will do exactly that and see if I can source one for a non inflated price, I have seen examples sell for as little as £50-60 so it can be done. Either way the output stage seems to be working just as it should so it seems as though the PEN replacement was a good choice by the previous owner.
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Old 2nd Jun 2023, 10:37 am   #7
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Default Re: His Masters Voice Fluid Light Five 442

I restored a set some years ago ,missing the o/p valve fitted an ac pen works fine I must have been mad ,I stripped the old rusty chassis and painted it a nice shade of grey ,I wonder if I am the only person to have done this . Mick.
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Old 3rd Jun 2023, 8:19 am   #8
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Default Re: His Masters Voice Fluid Light Five 442

My worry about using a Pen4VA or simiilar indirectly heated valve in place of the PX4 is that the heater draws appreciably higher current. How much latitude is there in the LT winding of the mains transformer?
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Old 3rd Jun 2023, 8:40 am   #9
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Originally Posted by kestrelmusic View Post
My worry about using a Pen4VA or simiilar indirectly heated valve in place of the PX4 is that the heater draws appreciably higher current. How much latitude is there in the LT winding of the mains transformer?
I have just noticed I fitted an AC2 pen and a resistor it must have been one I had at the time . I don't think I would any worries about the AC4 pen its a rather beefy mains tx ,unless someone intends to use the radio all day long most of us don't . Mick.
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Old 3rd Jun 2023, 1:24 pm   #10
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Default Re: His Masters Voice Fluid Light Five 442

Quote:
Originally Posted by Techman View Post


.....




I see that valve was produced in both B5 with side terminal and B7, I can't see the side contact, so it could be round the back or it's a B7 - I wonder which has been used?

Just thinking about it, you could use the B5 version without even having to change the base. You could be a bit of a butcher (to the valve, not the radio) and chop off most of the fifth (centre) pin of the valve and solder a connection from the stub of this cathode pin to one of the heater pins - you'd have to be careful, as the wire from the pinch goes all the way down through the pin to be soldered only at the bottom, so if you were careful to only cut the outer pin, you could use the wire from the pinch itself, bent round and soldered to the other pin. Then you could take a wire from the side contact screen connection and solder it to the anode pin to triode strap it and it would then be virtually plug and play. You'd have to check the anode current and make circuit adjustments if necessary. There'll be a hum bucker for the old directly heated valve below the chassis, whether this'll need any adjustment or alteration, I don't know, it's not something I've ever done, although I've seen it discussed in the past when 'triode' output valves have been removed for resale. Others may have their own ideas regarding what I've just described - it's only my own thoughts.


....



I wouldn't connect the cathode of an indirectly heated valve to one of the heater pins- the original filament's "cathode" connection is made to chassis via the heater winding and the "humdinger" pot's wiper. Connecting it to one end of the heater winding might have rather hummy results!


Other things being equal, I'd take the cathode to chassis via a resistor of half the "humdinger" pot's end to end resistance or perhaps some other value depending on the bias requirements of the triode strapped pentode.
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Old 4th Jun 2023, 12:10 am   #11
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Default Re: His Masters Voice Fluid Light Five 442

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I have just noticed I fitted an AC2 penMick.
When I first saw the post mentioning the AC/PEN valve I thought that's a perfect replacement seeing as it's got a 1 amp heater the same as the original. I had a look at my rather rough and ready valve list and noted that I've apparently got one somewhere, I also noted that I'd also got an AC2/PEN, but noted that it was getting on towards double the heater current. Now you've said that it's that valve that you're actually using. You've obviously proved that the transformer can take the increase in heater current and I would agree that they're likely to be a little over engineered and not likely to burn out and you can get away with it, so all's good. It looks like the AC/PEN is the perfect replacement with its 4 volt 1 amp heater, even though it might lack the efficiency of the original triode, although I haven't exactly studied the data. The problem is always going to be that any replacement valve that doesn't have the words 'highly desirable' written all over it is going to have more than 4 pins due to not being a triode and is also pretty much going to be indirectly heated, therefore needing a higher heater power for the same output.

I think it's likely that the OPs radio wasn't modified by its last owner, but had been done some long while before by a previous owner to that. Someone with the capability of doing the modification and neatly replacing a valve base socket is highly unlikely to be put off by a broken drive cord and not the sort of person to leave a load of wires disconnected. However, they might be the sort of person to twiddle a few things to try to improve performance when in fact another fault existed, so probably why the set is deaf. It could be that a combination of faults such as the band to gram switching and then the drive cord breaking being the final straw, so decided to let it go to another home.

It's a strange thing to say, but I think the fact that this set has had the modification to its output stage has made it much more interesting than if it was all original - given us something to talk about! It'll be interesting to see below the chassis as to what's been done with regards to the hum bucking circuit that I mentioned earlier and Chris has latterly enlarged upon in the last post - thanks Chris, I was wondering in respect to that.

The saddest thing of all of course, is not the modifications, but the fact that there's virtually nothing left to listen to any more with these old AM only sets - thank goodness there's still Radio 4 and Caroline, otherwise these sets would be pointless!
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Old 7th Jun 2023, 7:10 pm   #12
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Default Re: His Masters Voice Fluid Light Five 442

Hello everyone. Apologies for somewhat abandoning this thread I haven't had much time to frequent the forum over the past few days. Mick, your example looks very nice and I don't envy you stripping the chassis to paint, it's quite a busy chassis with many components and wiring and I'd be quite put off by that. The chassis of my example is a bit rusty but I think I'll just leave it as is! Kestrelmusic, I'm sure it will be okay with the AC4/Pen but I did share the initial concern. Running the radio for a few hours shows no real heat from the mains transformer and as Mick says it is somewhat over-engineered as were many EMI products of the time.

I still haven't yet had time to look over the radio yet but I hope to do so shortly. I hope that it hasn't been messed around with as per Techmans comments, I'd hope that the alignment hasn't been touched! Once I have the chassis out again I'll get some pictures of the output section and I'll look at what's been done to the hum circuit and post my findings.

It is a shame about AM slowly becoming silent, I may invest in or build a pantry transmitter to give them a suitalbe signal. Over here in Leicester there aren't really any strong stations that play decent music though there is a low power station operating from Loughborough that I just about receive okay that plays quite a good varied selection of music, hence the need to repair my aerial!
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