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Old 7th Mar 2018, 1:18 pm   #1
stuartwwillis
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Default Racal RA17

Hi, I'm new to the forum. I'm also a millennial. So please excuse my witlessness and unfamiliarity with what I'm about to request assistance with...

When I was 13 years old I snuck into my dad's shed and fiddled with the switches and turn dials on his prized Racal RA17. Suddenly, the lights went out on the rolling frequency display and the undulating static fell to silence. I ran from the shed as if I'd never been there in the first place.

Later that evening I was at the receiving end of my old man's bellowing voice as he had discovered what had happened. I had obviously left the dials and switches in a manner that only an 13 year old boy would. As a result, I had been rumbled. Despite being so young at the time I don't think he's ever truly forgiven me for it. It seems to hold sentimental value to him as he has kept it in his shed ever since. I'm 28 now and 15 years have passed. Its his birthday in September and I would love to present a working Racal RA17 receiver to him (preferably the original one).

Repair

I appreciate there could be any number of issues with it and it may be a long and painstaking process to get it working again but I am willing to try.

My questions are as follows:

- Is this likely to be a repair job I can do myself? i.e. are there some basic repair steps I can take first before getting it looked at by a professional?

- Is it possible to blow a fuse (or the equivalent in this receiver) by turning knobs and dials in a certain combination? Obviously it is as I've done it! But, I want to eliminate any other causes first.

- I live in Taunton, Somerset. Does anyone have any recommendations for somewhere I could take relatively local it to be looked at?

Thanks so much.

Stu
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Old 7th Mar 2018, 2:42 pm   #2
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Default Re: Racal RA17

I do not believe there are any combinations of front panel control settings which can damage an RA17. Let your conscience rest easy.

The scale lamp bulbs are powered from the main transformer and that from the mains via a switch and a voltage selector at the rear of the chassis, along with a fuse in a fuse-holder.

Most probably a fuse popped.

However, there are some components which degrade over time and 15 years after last use suggests you will probably be best with some help in getting it going again. There will be a fair amount of work involved in making sure the set is in a reliable condition, but they are worth it.

David
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Old 7th Mar 2018, 2:51 pm   #3
rambo1152
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Default Re: Racal RA17

The RA17 is a rather novel and unconventional design, many years ahead of its time, and can present a challenge to even an experienced radio engineer.

I think you were just unlucky to be in the wrong place at the wrong time, maybe the fault would have occured the next time your dad turned it on, turning the knobs wouldn't normally do anything detrimental.

The original problem may well have been trivial, perhaps even just a blown fuse, but the set may now have acquired other issues just by lying idle for years.

We have some RA17 specialists on the forum.
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Old 8th Mar 2018, 9:45 am   #4
vosperd
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Default Re: Racal RA17

My RA17 used to randomly blow a fuse on switching on, especially if I switched off and back on by accident.
It might be worth replacing the fuse with one of the correct rating and see what happens.
Others may not consider that good advice though.
Although where you will find a 16mm cartridge fuse these days I don't know.
The original smoothing caps are available if that turns out to be the problem.
Don m5aky

Last edited by vosperd; 8th Mar 2018 at 9:52 am.
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Old 8th Mar 2018, 10:07 am   #5
G8BBZ
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Default Re: Racal RA17

Hi Stu,
You don't say if you have any knowledge of electronics or access to any test equipment. Maybe you could let us know.
If you haven't already done so, it's worth checking 3 fuses - 2 located on the rear of the RA17 and the one in the mains plug. You will at least need some sort of testmeter to do this (or a supply of spare fuses). While you are looking at the rear panel check that there is a wire link between the two terminals marked HT1 and HT2. Make sure the set is switched off at this point or you might get a nasty shock from the voltage on these terminals.
If the fuses seem OK, then switch the set on, move the service switch to the "Man" position and give it 5 minutes to warm up. Remove the top cover from the set and look at each of the valves to make sure that you can see the red glow of the valve heater inside th valve. You may need to temporarily remove the screening can where fitted to see this and it can be easier in a darkened room than in full daylight. All the valves should have a glowing heater inside, any valve without a working heater will need to be replaced. If all the valves are OK, and if you have a testmeter, you can check the voltage on the HT1/HT2 terminals mentioned above. This should be about +250v measured with respect to chassis.
Perhaps you could do this and report back.
cheers
Peter G8BBZ
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Old 8th Mar 2018, 10:32 am   #6
Craig Sawyers
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Default Re: Racal RA17

There is a group on Yahoo Groups called RacalRA17forum . It is usually pretty quiet on there, but there is a lot of knowledge on there, so in addition to any advice you get here, that forum is worth joining. Rob Filby is the ultimate RA17 guru.

But there is nothing you could have done by knob twiddling that caused an RA17 to cease working. It was either a random blow of a fuse, or as a result of random short circuit in a valve for example, or a short in Plessey mains plug because of degraded insulation (yup!). It would have done the same if your dad had turned it on - you were just in the wrong place at the wrong time. A shame he took it so badly - at age 13 I encouraged my son and daughter to learn how to use electronics and tools properly.

Repair and alignment of one of these beasts take time, patience, and the correct equipment. 50-odd paper capacitors need to be replaced, always (the Hunts paper ones will, absolutely, be leaky or open circuit) just for starters, and any duff valves replaced. Dramatically out of spec resistors will need to be replaced. If any of the silver mica capacitors in the critical filters are duff, the filters will need to be realigned.

Anyway - you get the drift! But when a set is on song, it is as sensitive as most sets out there, and have the joy of much knob "twiddling" to get the best signal! I've had Radio Australia coming in as strongly as Radio 4. And that was on a side lobe of their transmissions to the Philippines.

Craig
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Old 8th Mar 2018, 11:16 am   #7
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Default Re: Racal RA17

Quote:
Originally Posted by Craig Sawyers View Post
"Anyway - you get the drift!"
An RA17? - I hope not! (sorry, couldn't resist it)

I did my Direct Entry Radio & Receivers Course at BBC Wood Norton in 1979; my trainer (David Yates - a real nice gent ... and still around, bless 'im) took me oh-so-carefully through the Wadley Loop principle - so when the relevant exam question came up, I was able to answer it with a fair degree of success. Came in very handy at Caversham/Crowsley Park - but I can't remember it now

At the risk of stating the obvious ... please be aware that these sets are heavy (at CAV/CRP, a two-person lift was mandatory when taking one out of its rack).

I hope that Al ('Skywave') will be able to help the OP on this one (and a warm welcome, Stu )

Cheers
Guy
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Old 8th Mar 2018, 12:11 pm   #8
Craig Sawyers
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Default Re: Racal RA17

Heavy - yup! well over half a hundredweight, or 31kg.
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Old 8th Mar 2018, 2:05 pm   #9
deliverance
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Default Re: Racal RA17

Rest assured there are members that are very knowledgeable regarding the R17 they will give you the help that you need .
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Old 8th Mar 2018, 3:21 pm   #10
ex seismic
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Default Re: Racal RA17

If it has sat in the shed for 15 years without use I'd start off by bringing it indoors for a week to dry out before letting the mains anywhere near it.

Gordon
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Old 8th Mar 2018, 10:38 pm   #11
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Default Re: Racal RA17

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
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Old 8th Mar 2018, 11:26 pm   #12
dave walsh
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Default Re: Racal RA17

This is all good stuff for the enthusiast and I've really enjoyed reading the history etc but does it mean anything to Stuart? We don't know his level of knowledge but it appears to be more speculative than accurate. It seems clear that he has built his concerns on a misconception that may well have preyed on his mind over the years. Now an independent Jury has brought in a unanimous verdict of Not Guilty on all charges !!!

Everyone would agree it's hardly a starter set but more a "Rolls Royce" [at the time] accounting for dad's reaction perhaps? There would seem to be at least two options-

1. Find someone who can carry out a [probaly very expensive] restoration before September. It's a great thought but what if he's actually not that bothered these days?

2. Discuss the whole episode with Dad see what he thinks!

It's possible that the issue does not loom as large with the father as it does with his extremely caring son. There's only one way to find out what he might really want as a Birthday Surprise! It could still be a surprise if the conversation is handled diplomatically.

Dave W

Last edited by dave walsh; 8th Mar 2018 at 11:40 pm. Reason: Even More Probaly Irrelevant Thoughts
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Old 9th Mar 2018, 12:45 am   #13
dtvmcdonald
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Default Re: Racal RA17

My RA17 died just like his, a couple of weeks back. It was a bad fuse.
The specified fuse (375 mA fast blow or 250 mA slo blow) was not in
my stock so I used a 300 mA fast blow. When I looked up the fuse lifetime
after the restoration a year ago, at the measured current it was quite finite. The fuse blew within the expected range of time.

Luckily I have a US model, and it had fuses that are still US standard size.
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Old 9th Mar 2018, 6:52 pm   #14
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Default Re: Racal RA17

Stu,
Try this for help: http://www.chavfreezone.me.uk/ra17-r...n-service.html

This guy advertise on he net that he repairs Racal Ra 17 all variations. he also sell parts. I bought the "Finger Gards" for the large tuning knobs from him some time ago.

Jan
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Old 9th Mar 2018, 11:27 pm   #15
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Default Re: Racal RA17

That's Ian.

He knows his way around Racal receivers very well indeed. I've seen a couple of RA17 he's restored along with some of his personal collection. Colin at the Lothians Radio Society has one he restored. He's just a bit far from the OP.

I love the chavfreezone address. One of the microwave/moonbounce guys has 'marsport'

David GM4ZNX
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Old 10th Mar 2018, 12:20 am   #16
dave walsh
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Default Re: Racal RA17

Ian is obviously a high quality repairer but as I said, these services aren't cheap When Stuart sorts out how he wants to approach things we will know more perhaps.

Dave
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Old 10th Mar 2018, 9:47 am   #17
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Default Re: Racal RA17

Ian's restorations are a good bench mark for what it takes to do a thorough job on one of these radios. As far as hourly rates go, I think he's about one tenth of what a main dealer charges for work on my car. Once done to this standard the radio can be expected to be back to full new performance and with modern components where the old ones were known to degrade, the reliability is probably better than new sets ever enjoyed. Treat this as the reference price, doing the full thing and paying someone a modest price for their time. With there being a definite date for a birthday, one thing Ian's price buys you is confidence of it being done in time.

Finding someone closer will save a lot of money on transportation and a lot of inconvenience.

Finding someone to act as a mentor/guide, doing it just for the fun of it and for getting someone new going in the hobby, will save a lot of money too, but Stu will have to get involved. There are no expensive parts involved.

Not doing a full-blooded rebuild and just hunting down whatever parts have actually failed will save a small amount of money on parts, but can save a lot of time if the fault is found quickly. The drawback is that you can't be as confident in its future reliability.

An RA17 is a radio very well worth fixing.

Oh, if you watch the film 'Goldfinger' in the scene where Goldfinger is about to bisect James Bond with his laser, there is a whole wall of RA17s and their accessories as the backdrop. Everyone except a true radio guy will be watching only where the laser is pointing.

David
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Old 10th Mar 2018, 11:31 am   #18
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Default Re: Racal RA17

Some photos of a 'loop' (?collective noun?) of RA17s plus a few others.
As contained within Martin Ellen's excellent site, bbceng.info
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Old 10th Mar 2018, 11:40 am   #19
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Default Re: Racal RA17

Quote:
Originally Posted by Radio Wrangler View Post
. ... if you watch the film 'Goldfinger' in the scene where Goldfinger is about to bisect James Bond with his laser, there is a whole wall of RA17s and their accessories as the backdrop. Everyone except a true radio guy will be watching only where the laser is pointing.
"You expect me to lock, Goldfinger?"

"No, Mr Racal - I expect you to drift!"

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Old 10th Mar 2018, 12:27 pm   #20
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Default Re: Racal RA17

Quote:
Originally Posted by Nymrod121 View Post
Some photos of a 'loop' (?collective noun?) of RA17s plus a few others.
As contained within Martin Ellen's excellent site, bbceng.info
Guy
"No, we haven't had to use the radiators since winter '62"....

With all those blank panels above and below in the first pic, I think I might have arranged at least 1U between lower and upper receivers! Are they panoramic displays with small screens associated with each receiver? I wondered how much of that lot ended up as landfill or smelter-fodder, such is the way of the professional world.

I was curious if it was a chart-recorder above the foreground BRT400 in the second shot, but it might just have been a pasty-warming shelf. I recall professional outfitters offering 19" rack-mount microwave (cooker, not TX/RX devices) metalwork and even wine racks!
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