[Radio Wrangler]

To give you an idea of what an RA17 is...

Back in the 1960s, most radio amateurs used war surplus communications receivers. The HRO and AR88 from America were popular, the main British contender was the CR100. If you were doing it on pocket money, the R1155 from a bomber aircraft was cheap though less desirable, and the '19 set' from a tank was bargain basement. If you were seriously well off, you might have bought yourself a new Eddystone, and their EA12 model, covering the amateur bands only had people drooling. The EA12 was a double superhet, with a bank of quartz crystals keeping its high frequency oscillator stable. All the others were simple single-superhets and their designers had tried to use temperature sensitive capacitors in their attempt to reduce temperature-caused drift of their tuning. They were crude, but they worked. You had to keep adjusting their tuning to stay on your wanted station and it got worse on the higher frequency bands. Their tuning scales were a bit coarse and you might be able to reckon where you were tuned to within 50kHz on the easier bands. Have a google around and take a look at what most people were using back in the day.

I saved up all my pocket money, Christmas and birthday presents and did whatever lucrative odd jobs were available and i bought myself an AR88 in the mid 1960s. A fair feat for a schoolboy. I still have it. Some years ago I was offered an Eddystone EA12... its first owner had also owned a brewery! which gives you a clue as to the market for these things

Through all this period, there were rumours of some amazing receivers. The RCA AR8516L was a ship's job. The occasional one changed hands in the back pages of Shortwave Magazine after a number were released onto the surplus market. This was odd becauseMarconi dominated the radio rooms of big ships, and they took their radios back when they were replaced. Remarkably few of these are on the loose even today.

But the king of all the rumoured radios was called the Racal RA17. Heard of, but not seen unless you worked for major organisations which could afford such things. They employed 'Frequency Synthesis' whatever that was. I hadn't a clue then, but it sounded brilliant! They were also said to have a moving film strip scale five feet long!!! Then there was mention of soething called a Wadley loop, Wadley system, or Wadley triple mix. There was no internet to look these things up on. This RA17 receiver had to be the most sophisticated thing imaginable, and the power of the imagination put it a bit beyond reality.

If your dad grew up in that period, getting an RA17 will feel like having got hold of a Mclaren F1 or a Bugatti Veyron.

In the late 70s and through the 80's a lot of RA17s came on the market and the second-hand prices dropped. They became quite affordable. But if you were a lad in the era when they were just a legend of something you had never seen, the glamour remained.

The Americans had a super receiver too, the Collins R390A. It was considered so good that it's existence was kept a classified secret for a number of years. The RA17 is in that league, but the RA17 is a lot cleverer. The R390A was more convenientto tune across a band, turning one knob, while on the RA17 you had to keep trimming the position of a second and third knob as you tuned the main one. Still, what was inside the RA17 made the R390A look like a very elaborate museum piece.

Fast forward to fifteen years ago.

With a valved radio sitting there running, allthe valves are hot and running, the power supply reservoir capacitors are fully charged and all is OK. When the set was turned on, those reservoir capacitors would have liked to take a sudden surge of current to charge them up very quickly, but they didn't get it. The rectifier (converts AC to DC)valve would have been cold. As the rectifier's cathode warmed up, it would start to allow a progressively increasing current to the reservoirs. A nice, gentle soft-start. No nasty surprises.

Say a young lad switches the power switch off for a short while, and then back on again.

The voltage on the reservoir capacitors starts to fall as it powers the radio but doesn't get recharged with the ains input switched off. All the valves start to cool, but that takes time. Back on goes the mains switch but this time, the turning on has happened while the rectifier valve is still quit warm and is ready to work. All of a sudden, the mains tries to charge the reservoir capacitors back up. The rectifier valve is still hot and it's up for it! No soft start tis time!

The sudden surge of current is just what it takes to pop a fuse. And then you have a fully dead set.

Counter intuitively, a fully dead set is an awful lot better than a set which is just performing poorly, and both are an awful lot better than one with an intermittent fault. Most likely there is a single point of failure, and it ought to be easy to find.

The advice to bring it in from the cold and keep it in a warm, dry room for a week or so is very good advice indeed. This can be going on while you organise some local help and guidance.

Once it's had a time to dry out, and you've replaced any blown fuses, you can give it a try.

However, if you are going to get it fixed and give it to your dad, he's going to use it, so it makes sense to check through the thing. There are a number of components which are known to degrade over time and you can expect to find some of them in poor condition. This will take time, but the components needed are 1) cheap 2) easily obtained and 3) the new ones will last much longer.

Anyone who is going to go through this for you is going to want to do it with you involved. You're going to learn a lot, and you might just be infected with a new hobby.

It's incurable.

david