Bush VHF81 (around 1964)

In 2010, I bought this radio through the Dutch forum on old radios. I liked its typical 1960's modern functional look and I was curious to see how this AC/DC radio with VHF FM band would perform.

It has no PCB, the radio is built on a vertically mounted aluminium chassis with components soldered on supports and valve sockets. The VHF tuner is a separate metal box.

The valve line-up is:

• UCC85 as FM frequency changer,
• UF89 as first FM IF amplifier or RF amplifier on LW and MW,
• UCH81 as frequency changer on AM or second IF amplifier on FM,
• UF89 as first AM IF amplifier or third FM IF amplifier,
• UABC80 as AM detector, FM ratio detector and AF pre-amplifier,
• UL84 as AF output amplifier,
• UY85 as mains rectifier.

These all have 100 mA heaters for series connection. The two dial lamps are also in the heater circuit. The valves in this radio are all from Mullard and are carrying production dates from 1963 and 1964. Some are stamped Made In Great Britain, some Foreign Made. The power supply capacitor has a date stamp from October 1964.

When I collected this radio, the wooden case was looking dreadful, having an opaque, dried-out, cracked finish. The inside was a bit greasy. I took the chassis from the case, disconnected the speaker, pulled the valves, removed the dial glass and started to clean the chassis. The chassis looked much better after this.

Trying the tuning knob made the tuning cord break. It seemed the tuning condenser was a bit stuck but the real cause was that the tuning cord was brittle and weakened by time and wasn't able to convey the force needed to move the tuning mechanism.

This was quite disappointing. After this setback, I put the radio in a box on a shelf, where it stayed for years before I picked it up again and started a serious restoration effort.

I wanted to fix the broken tuning cord first. I removed the two broken pieces of cord and measured them.

I pried open the clip that holds both ends and made a knew tuning cord from stock, 111.5 cm long. The knots on both ends secured with nail polish and reinserted in the clip. Then I threaded the cord over the spindle and wheels and reapplied the tension spring. Everything was moving smoothly again.

After this, I reformed the electrolytics in the power supply. This went well, they turned out to be in good condition. I replaced the mains decoupling capacitor, which was very leaky and waiting to cause trouble. I also replaced the leaky coupling capacitor to the output valve and a few cracked Hunts decoupling capacitors. Then I thoroughly cleaned the band switch. After dealing with these usual suspects, I connected the radio to an isolation transformer and turned it on.

There seemed to be no light from the heaters nor the dial lamps. I turned to my multimeter to check the heater circuit but suddenly there was a hiss. LW and MW bands were working. I switched to VHF and got some hiss. Adding an antenna wire, I had FM reception and quite clear, though a bit distorted on most stations.

One of the dial lights was interrupted. I tried to unscrew it but the lamps were stuck in their holders and impossible to remove. I unsoldered the lamp holder of the defective light and saw there was some greenish corrosion between the socket and the base of the lamp. Applying WD40 and some heat did't work. When I applied too much force, the glass bulb came loose from its base. That made things easier. I pinched the base and pried it out. The socket had lots of green and blueish goo in it. Possibly resulting from a chemical reaction between the brass lamp base and some chemical compound in the plastic of the lamp holder. On the UK Vintage Radio site I found several accounts of the same phenomenon of corroded dial lights on this type of radio. I thoroughly cleaned the lamp holder and replaced the lamp with a 6V-100mA lamp I had. After this, the dial lights were working fine again.

Then I turned to restore the cabinet. I removed the baffle and plastic parts. They needed some serious cleaning. So did the two knobs. I took the empty cabinet and carefully carefully sanded off the dull varnish, which was dried out and came off easily. This made the wood much lighter. I decided to use a clear spray varnish but first I made the veneer a bit darker using water stain. The water caused some of the veneer to come loose, so it had to be reglued.

While I was taking the case apart I realised in surprise that this radio is actually quite unsafe. The 5 metal supports for the chassis are screwed to the wooden case without any additional isolation. At the front, only a layer of speaker cloth is separating my fingers from the heads of the live screws through the speaker baffle. First I suspected that some isolation washers had been lost during a previous repair but looking at pictures of other VHF 81s it turned out that this radio is originally built this way. Maybe the explanation lies in the predecessor model, the VHF 80, that uses the same chassis but comes in a Bakelite cabinet. Bush may have forgotten to address the safety aspects of placing this AC/DC chassis in a wooden cabinet. Who knows?

The distortion on FM reception was removed by replacing the electrolytic in the ratio detector, which had almost zero capacity. I checked the voltages on all the tubes. Most were on the high side, but not too much, which may mean that the UF89s and UCH81 are a bit worn. For want of replacements and being satisfied with this radio's performance, I decided to leave them.

I put the cleaned dial glass and control knobs back in place and reassembled the radio. After removing the temporary supports, I mounted the chassis in the repainted cabinet and connected the speaker again. I put the heat deflector (a piece of Prespane) back in place as well as and the back panel with its built-in VHF antenna. This radio is working fine again.