Bush VHF62

[AlanC]

I've been wanting to get my hands on one of these for a long time. The story goes back to my childhood, when my parents had one. It was a really special purchase for them; bought in the year of my birth (1958) and represented much pushing out of the proverbial boat- and they were justly proud of it. It replaced a battery operated set of some forgotten vintage that according to my mother, didn't work very well and got through batteries at a prodigious rate. Some of my early memories from the mid sixties featured this radio- it lived in the kitchen and I have this really powerful memory of my mum preparing dinner with The Supremes 'Baby Love' (first time round!) playing in the background. I'd have been 8 then. As I grew up, I loved tuning around on the radio- I remember finding Luxembourg, and later on the 2nd generation pirates, Caroline, Radio North Sea International and others. To add extra interest at the top end of the VHF band there was the police transmissions in those days. Then in my mid teens, every Sunday evening I'd tune it into the top 20 show.

Unfortunately however, the radio didn't survive much beyond that. It gradually migrated more and more often into my bedroom, until that became it's new home. Then as my hobby grew and I needed parts to fuel the construction of my own receivers, it started lending at first the odd valve, then the odd transformer, finally the IF cans.... I will never forget the look on my mum's face when she discovered this, for as I said the set had been really special to her and my dad.

So partly out of guilt, and partly for sentimental reasons I wanted to get another one and restore it, and return it to my mum- who is still alive and well and 88 years young.

All of which kind of brings us to where we are now- courtesy of eBay and a lady called Lucy. The external appearance of the VHF62 changed a bit during it's production life, with differences to the knobs and the trim. So as soon as I saw this one, I knew it was the one I wanted. It was identical in every respect to the one I'd grown up with. Lucy's dad even offered to meet me near Nottingham to save me having to drive from Sheffield to Folkestone to collect it- it doesn't get better than that!

But so much for the story....

The initial inspection revealed a very clean example with some water marks and scratches to the cabinet top but other than that, just the general scratches and dings elsewhere that you expect on anything 57 years old, the author of this post not excepted!! The back was removed and inside was that thick layer of undisturbed dust that we all like to see, on top of a complete and unmolested chassis. This was carefully removed from the case and a detailed inspection carried out. The under chassis was clean and beautifully made, full of the dreaded Hunts Mouldseals of course but they hadn't split. The only previous work that has been done that I have discovered was that C56 ('that' capacitor!) has been replaced with a 70's vintage mustard colour one, and the EM81 had been replaced with a Mazda branded one. This latter discovery was greeted with some joy as it meant that the magic eye might actually emit some light, unlike the many I've seen recently.

Since 'that' capacitor had been replaced, and since the seller told me that she had plugged it in and it had worked, it seemed a bit pointless to run it on the lamp limiter and after a minute spent stroking the chin I decided to take the plunge, throw some mains at it and see what happened. I hit the MW piano key and retired to a safe distance- and to my surprise the dial light lit. After the normal warm up period, the eye came up green and up came the buzzing hash that we get on MW around here.

MW and LW seemed reasonable if a bit low, VHF didn't work at all at first until I worked the piano key switches a few times; then it picked up a few stations but was woefully deaf and as you tuned through the station, at the point of maximum deflection of the magic eye there was a kind of null with very quiet distorted audio; either side of this you could get reasonable audio but it was still low and somewhat distorted. I also observed that the tuning mechanism was a bit sticky, but the volume and tone pots were perfect- no scratchiness at all. Not a bad start.

So my assessment was that it was generally all working, but in need of a bit of TLC and possibly realignment. At this point downloaded the Bush service sheet from 'up there' and ordered a load of capacitors- 10 off each 1n, 5n, 10n, 22n, 39n and 100n. While waiting for the caps to come I gave the chassis a good clean. The knobs came off easily and I carefully removed the dial glass, noting that the rubber protectors at the clamping points had solidified rock hard. I haven't replaced them as they seem to want to stay in one piece. The cream painted metal backing plate behind the dial was cleaned, as was the pointer (cursor). The solidified old grease was carefully removed from the track that the pointer runs along and was replaced with a thin coat of new grease, and the many pulleys that there are on this set were sparingly lubed at their pivots with clock oil. This is really useful stuff, designed not to dry out. You can order it online from a number of horologist's suppliers. The mechanism freed off nicely then and the only other thing I did was to bend the cursor slightly backwards toward the back plate as it had a tendency to rub on the back of the dial glass.

To remove the chassis altogether on one of these, first loosen the two uppermost 4BA nuts holding the speaker in, so you can release the speaker leads and the magic eye cables from the clamps. Then you need to loosen the two screws on top of the output transformer and slip off the speaker lead tags, then unclip the ferrite rod from its brackets at the top right of the case. Lastly, carefully pull the magic eye downwards and away from the baffle, to remove it from the spring retainer. When you do this, grip the spring with long-nose pliers to prevent it from snapping against the top pip of the valve, which would probably break the precious EM81. Place the chassis down carefully ensuring that it is not resting on the ferrite rod or the magic eye- the EM81 can be unplugged and put somewhere safe. A solder reel makes a handy prop under the mains tran end of the chassis so it's not resting on the EL84!

It's possible to work on the chassis underside however without doing any of that, in the following way. First, switch off and unplug, then place the radio on something soft like an old towel. Lay the radio on its face and remove the 4 2BA bolts underneath. Then unplug the internal VHF aerial and remove the back, and stand the set upright on its base with the open back facing you. Then carefully grip the chassis deck flanges at either side and withdraw it, rotating it in the horizontal plane as you do so, so that the top of the chassis is facing the inside of the cabinet with the knobs and dial downwards, resting on your soft surface. If you get this right, none of the cables are strained at all.

I started the re-capping operation with the Hunts Mouldseals; the layout of this set is so easy to find your way around that it is a delight to work on and it doesn't take long to replace them all. I did them one at a time and marked them off on the circuit diagram as I went with a highlighter pen. Each one is then inspected to double check it is securely soldered and wired to the correct tags. When soldering to valveholder tags always remove the valve as otherwise there is a chance that the heat travelling up the pin could crack the glass. Where the leads of the old cap were sleeved I transferred the sleeve to the new one. Having done all the Mouldseals, I then proceeded to do the two 0.01uF waxies that are under the chassis; one of these is mounted between two adjacent wafers of the wavechange switch.

I tested the old capacitors as they came out, none of them gave sensible readings- the mouldseals all exhibited leakage to some degree or other, and gave capacitance readings on my Fluke 175 that bore no relationship whatsoever to what was written on them! One of the two 0.05uF waxies was practically dead short, which would have robbed the EABC80 triode of its contact potential bias (the grid leak is 15 megohms!!). On the topic of resistors, most of them were spot on, but a couple were a bit high- the ECH81 cathode resistor was 177 ohms instead of 150 and a couple more were like this. But I decided to leave them alone for now.

At this point I decided to give the radio a run, and wow what a difference! I had to turn the volume down a long way, and not only was the set really sensitive on MW and LW but there was the normal interstation hiss on VHF. However, with an aerial connected, even though signals were now closing the magic eye to about 2/3rds, the problem with the VHF alignment was very obviously still there.

Now FM discriminators are complex things. They will work well, as long as all the capacitors are in good order, the diodes are okay and reasonably matched, and if they are properly aligned. Deciding to tackle this next, I checked the large 5uF electrolytic capacitor and it tested absoulutely fine. It is a high-quality component, an identical one is fitted to my Leak Troughline Stereo tuner in fact. The state of smaller 270pF caps and the state of the EABC80 were simply unknown, but in the absense of contrary evidence I gave them the benefit of the doubt.

Since I had resigned myself to spending a lot of time debugging this part of the set, with test gear if necessary, I considered that there was nothing to loose by trying the effect of tweaking the discriminator secondary core. And before you shout "twiddler!!!" or worse names, I have worked on FM communications receivers a lot professionally so I know my way around Foster-Seeley's, quadrature detectors, and ratio detectors too of course. Well that was my excuse, anyway...

So I dug out the correct tool and tuned the set to Radio Three, tuning for maximum voltage on the test point beside the final IFT. You must let the set warm up for at least 15 minutes, as the tuning does drift a bit at first. The diagram in the service sheet shows how to make an alignment jig consisting of two 100k resistors. Connecting this as per the circuit and using the Fluke as an indicator, gave a DC voltage of about -3.6V. The transformer secondary, which you use to zero the discriminator, is the bottom core as has been said many times before in this forum. Turning the core (not by much- I doubt it was more than half a turn) brought the voltage to zero, and it was obviously going to go positive on the other side. I noticed straightaway that as the zero point was reached, the audio came up in volume and became very clear. Incidentally, you can expect a surprisingly large voltage on the test point; -15 volts or on a good signal.

So now I had an apparently fully functional radio. There were just two problems. One was, I'd noticed while checking a few voltages that the HT was low- only 200 volts on the reservoir capacitor. And it was nagging on my mind that I hadn't changed the few caps clustered around the output transformer, which included two Mouldseals and a waxie! So a serviceable EZ80 was found and fitted, which resulted in yet another transformation; the magic eye was not only noticeably brighter, but now closed completely on strong FM stations. Meanwhile, plenty of weak stations were audible as well.

I then set about changing the remaining caps. The one surprise here was that after the 0.1uF mouldseal C56 in the negative feedback loop had been changed (I also changed the 4.7K resistor R32 in series with it, which was reading nearly 6K) the audio from the set, which had been a bit woolly and boxy, became very nice indeed, with a very pleasant bass response.

The audio stages on these sets are complicated by the use of negative feedback. The EL84 cathode resistor is unbypassed, but there is also a feedback loop from the output transformer secondary to the bottom end of the volume control, where two shunt resistors effectively set the gain of the amplifier. One of these is shorted on MW/LW by a section of the wavechange switch, boosting the gain on AM. When working properly, there should be little difference between the level of a reasonably strong MW station, and BBC VHF stations. I say BBC because the independants further up the dial all seem to use more deviation than the VHF62 was designed for resulting in excessive audio level and distortion.

After a good soak test I considered the chassis done, and now I turned to the cabinet. The top had places where the original varnish finish was chipped right through and water had obviously got into the veneer. Now as others have observed on our forum before, it's sometimes necessary to try a number of different methods until you get the result you want. This turned out to be liberal dosings of Lord Sheraton's restorer and then filling the holes in the varnish and the worst scratches with Humbrol clear polyurethane and allowing to dry before smoothing with very fine wet and dry. Finally, Colron finishing wax was applied and the surface buffed up, bearing in mind you don't want a mirror finish as the original finish was rather more satin than gloss. The result isn't perfect if you inspect it closely, but otherwise it's very acceptable and from a distance looks great. There was a gouge on one of the cabinet sides that needed a slight colouring; for this I used a felt tip pen from one of those packs of 20 different colours that you buy the kids to keep them busy on a rainy day. I matched the colour hue first, then scribbled on a piece of card and then before it dried, used the end of my finger to transfer to the wood; building it up until I had the exact density.

The knobs then had their brightwork Brasso'ed and then scrubbed to remove all the muck in the grooves; the brass inserts were then lacquered with the Humbrol and allowed to dry before refitting. The B-U-S-H letters on the cabinet front where similarly treated. The magic eye bezel, the speaker cloth and the metal trim below the baffle were all in fine condition and were left alone.

One thing I have noticed is that the rear edges of the piano key buttons aren't straight- see the photo below. I don't consider this a problem; but I would like to know if they are all like this!

A couple of tips when working with these radios. When reassembling, the magic eye flying lead needs to be secured under the clip at the top left of the speaker- you'll need to loosen the 4BA nut securing the corner of the speaker to do this. You will find a rubber sleeve on the leads- fit this under the clip, and route the leads as per the photo below. The point behind this is twofold- firstly, the leads will get tangled in the tuning mech if you don't, and secondly, keeping them as far away as possible from the ferrite rod which dramatically reduces noise pickup on MW and LW. I don't know why but it does.

Secondly when refitting the chassis, screw in all the 2BA bolts with their washers but don't tighten them just yet. Now stand the radio on its base, and look at the front. Slide the chassis to one side or the other until the piano keys are centered within their aperture, and the distance from the cabinet to the gold 'coachline' on the dial glass is the same on each side. Then tilt the set forward, ensuring the chassis is as far forward as it can go, and tighten the bolts.

Finally, just a couple of observations relating to questions I see asked regularly in the forums; we've already dealt with the FM IF alignment and it's not hard to do. Firstly the mains transformer- how hot does it get? The answer- just warm to the touch after being on for hours. secondly, does the volume turn right down? The answer- no, but it goes very very quiet though. The bottom end of the volume pot doesn't go to chassis earth but to a 'virtual earth' point in the negative feedback loop. I am guessing that if there is a significant level of audio with the volume turned right down, then there is a problem with the components in the feedback circuit itself.

The radio is currently in daily use and so far it hasn't missed a beat. As I write this I'm listening to the test match on R4 Long Wave and I'm delighted with both it's appearance and its performance, and proud of the end results of my labour. My wife has fallen in love with it and doesn't want it to go to its new home!

In conclusion, although not a beginner's set the VHF62 is very restorable mainly as a result of the original build quality being so good. And as long as you don't mind the VHF coverage only extending to about 101 MHz (I can just tune in Classic FM at the extreme right hand edge of the scale), the VHF62 is a good, everyday practical radio and delivers an excellent performance in terms of sensitivity and audio quality. My total outlay on restoration was about £27, for capacitors and a NOS EZ80 bought to replace my spare.

Key to pictures:
1. Thick layer of undisturbed dust that we all like to see...
2. Mazda EM81
3. Cleaned and lubed tuning drive and dial back plate (sorry for poor image)
4. 'That' capacitor replaced in the 70's or 80's...
5. Under chassis view around the ECH81 and first EF89 areas showing general condition

[AlanC]

Key to images:
1. Components mounted on output transformer
2. Finished receiver
3. Finished receiver
4. Correct routing of cables within cabinet
5. Higgledy Piggledy piano key buttons!

[Kevin Hoyland]

Hello.
Outstanding post and work. I have 2 VHF62s and the Keys are the same has yours out of line, The 2 VHF 64s i have look the the same as well.
Regards
Kev.

Ps not far from you i live in Wombwell.

[mark pirate]

Very nicely done and written up
These are a very nice set, my example is still awaiting it's turn on the bench, but still works surprisingly well with it's original caps, although the EM81 will also need replacing.

Maybe when you have given the set to your mother, you could treat yourself to a Bush VHF64?

Mark

[frankmcvey]

Nice job, nice radio and nice writeup - thank you!

[AlanC]

Thanks for your kind comments Kev Mark and Frank, and thanks for the info Kev re the keys.

I would like to do a VHF64 at some point Mark, though I have a VTR103 lined up next and an Invicta octal valve set to finish off

I like working on Bush stuff; my first ever restoration was an AC31 and I'm on the look out for a TR90 at the moment.

[Wellington]

Alan - excellent result and an entertaining write-up - well done!

I have an unrestored VHF61 with crooked piano keys - I looked at them and thought: 'They must be off another set -they can't be original', but it seems they are.

I liked your memory of hearing 'Baby Love' in the kitchen when you were eight! I'm sure many of us have signal memories of songs heard on old radios (mine is 'Vienna' by Ultravox, coming out of a Ferguson 201C in the 1980s).

Let us know what your Mum thinks of it.

[McMurdo]

great write-up Alan. I'm not a huge fan of piano-key radios generally but the VHF62 is a pretty cabinet and they're a really useable radio..not as large as the continental sets and they look better for their compactness. I think the flat-top shows the wood grain off beautifully. HWMBO has the version in rosewood veneer, I wonder how many colour variants there were.

[Hybrid tellies]

A brilliant and enjoyable write up. I have an unrestored VHF61 and the piano key buttons are the same as yours.

[Tazman1966]

Same here! I have a VHF61 with wonky piano keys!

A super write up and a nice result. I hope your mum likes it.

[kingplum]

Thank you for a great write up and a lovely story.