RA17W where to start - UK Vintage Radio Repair and Restoration Discussion Forum

morecider · 24th Apr 2010, 3:12 pm

Hi all
Ive just finished my AR88D

Now Its time to have ago at my Racal Ra17w
Is there anything I should look out for before I power it up.
Plus Its full of hunts metallished paper capacitors, so would it be best to replace these on sight.
Just downloaded service a manual and removed covers so far
Cheers

Pete

AlanBeckett · 24th Apr 2010, 11:54 pm

My B40C, which predates your RA17, is riddled with metalised paper capacitors.
As far as I can tell, they all work beautifully

Alan

MikeTheBrewer · 25th Apr 2010, 12:06 am

Hi Pete,
I have the RA17L, never had any probs with the capacitors, although if you find you have low signal strengths the anode and screen bypass caps are often suspect, especially in the RF and demodulator/AGC areas.
Have you had any re-alignment probs with your AR88D ? I read up on it and it seems a bit of a challenge ( mine is still on the bench with low sinals on one band only..the others are dead.
Mike.

Station X · 25th Apr 2010, 12:39 pm

Please start a new thread regarding AR88 alignment. This one is about RA17Ls

XTC · 26th Apr 2010, 11:37 am

Start with the mains lead and connections. Make sure it's properly wired and fused and and the case is earthed.

Next eyeball the whole set for replaced components and bodges. Look for anything obviously burned. If you find anything odd, investigate.

Check the main smoothing cap for a bulging vent and reform it. The smoothing cap is hard to get at.
Check that the crystal is a 1MHz one. It probably is, but if you assume that and it isn't, it's a phenomenal waste of time.

Power the set up gently through a lamp limiter and check that the voltages are what you expect.
Make sure the audio section works. When that works, go to the IF section and set it up as per the instructions.

The caps don't seem to cause many problems. You'll almost certainly find a lot of resistors which have gone O/C or hopelessly high.

According to this

http://www.recelectronics.demon.co.uk/ra17.htm

The RA17W is a minor variant of the RA17L with different IF bandwidths.

As for mechanical problems, an obvious one is the film scale roller. It tends to stick and a flat wears on the roller. This is not good for the film scale and not the way it should be. You haven't got much option but to press the roller and bearings out and get a replacement roller machined up. If the bearings are rusted and grotty and don't respond to good clean and lubrication, they are probably standard parts. If you are in luck you'll see the roller turn easily with the slightest movement of the film scale and the roller will show no signs of flats.

Pete.

morecider · 26th Apr 2010, 6:49 pm

Hi
Thank you all for the advice/tips

now its sat on me bench with a few more resistors to check
Then hopefully ready for the big switch on this weekend
so fingers crossed

Cheers

pete

morecider · 8th Jun 2010, 4:53 pm

Hi All
What a nightmare of a project maybe bit off more than i can chew
I have now got the output stage working now
Both 1st/2nd VFOs and IF had high/burnt out resistors etc so no more smoke
V24 replaced cv464
but still can not pick up anything but hash noise
any ideas where to go from here Please

Cheers

pete

RobinBirch · 8th Jun 2010, 7:08 pm

What do you have in the way of test gear? You won't be able to do this without a decent signal generator and one of the filter chains needs a good wobbulator. I haven't got the manual to hand but in essence work through backwards from the AF to the RF.

If you get stuck I'll dig the manual out but there are many people on this site who have been down this path who can help.

Robin

Skywave · 8th Jun 2010, 7:29 pm

Quote:

Originally Posted by RobinBirch

What do you have in the way of test gear? You won't be able to do this without a decent signal generator and . . . .
Robin

. . . and a decent 'scope, too

; time-base to about 100MHz is the 'order of the day' for sorting out one of these - and the manual, of course!

Al. / Skywave.

cougar_lou · 14th Jun 2010, 9:35 am

Greetings to all.
If anyone seriously believes they can restore any RA17 variant to correct working order WITHOUT replacing the dreaded Hunts paper capacitors then they are dreamers of the first order!
Measure the leakage current of any of these dreadful things with 350Volts applied and you will soon see what I mean.Sure,you can have leaky cathode bypass capacitors but these will continue to fall below acceptable limits.
Don't fool yourseleves,replace all these monsters,after all,how many times do you want to dismantle a 17,especially the firt and second VFOs?

Brian G.

Station X · 14th Jun 2010, 10:22 am

I'm not familiar with these sets, but the original post describes the capacitors as metallised paper. This could mean capacitors with a paper dielectric housed in a metal can. I've restored some military gear containing such capacitors and they were in excellent condition with hardly any electrical leakage.

On the other hand if metallised paper means waxies replace them all.

Sean Williams · 14th Jun 2010, 11:27 am

I have an RA17L part way through restoration, and so far have only had to replace faulty resistors (and not too many of those either)

The caps that are fitted to these are indeed Metallised Paper - and are utterly reliable in my experience - the only "waxies" I have found on mine were acting as mains input filter caps - they only lasted a few moments once power had been applied!

Seems that RA17s are addictive - I've just purchased two more!

Cheers
Sean

amornummi · 5th Jul 2010, 12:06 am

I have repaired many RA17's. Two faults have been the tiny tubular 0.005 caps. One stopped the 1 meg oscillator going. The other was in the 1.6 meg if in a 117, open. Caused 10 db low gain. A pig to find.

If you really must do something, check the ones on the agc line. 10 megohm is ok as there is 470k to ground and 20 meg pulling up to HT!

Colinaps · 21st Jul 2010, 2:44 pm

If the set has been stored in a shed or garage, shove it in the airing cupboard for a couple of weeks.

First job is to make sure the right valves are in the right holes - never overestimate the previous owners!!! Pull them and replace to give the contacts a wipe, ditto with the crystal.

Look for puddles of wax on the bottom covers. I would change those that have left a puddle or are badly blackened and check the resistors in their associated circuits.
Check the mains voltage taps.
Run it up slowly either with a variac or series 100W bulb and once you have worked up the confidence to apply the mains directly and haven't seen any smoke, do a voltage check on the valve bases you can reach as per the manual. It will probably be running by now anyway. Give all the valves a wiggle to check for noisy contacts

You'd be surprised how far off spec components can be, while still allowing the set to work comparatively well. The only duff caps I have ever seen (in the couple of dozen I have had my hands in) actually stopping the radio from functioning completely are the silver micas in the IF strip (C210, 211, 212) and occasionally those in the filter sections.

You must have done all this by now anyway, unless you are remarkably patient - does she go? nudge nudge etc...

saxmaniac · 22nd Jul 2010, 5:02 pm

You really must have a very accurate signal generator capable of 40mc/s at least, plus a good scope and the manual is excellent, so if you want one I can PDF it to you, measure voltages, inject signals and measure as directed in the manuals, a lot of times stages can be isolated to narrow down faults

The poisonus capacitors are any of the black Hunts paper ones, the cases are often cracked & open to air and they were all leaky 30 years ago! Other types I have found can be risked if you dont want a huge amount of work

24th Apr 2010, 3:12 pm	#1
morecider Retired Dormant Member Join Date: May 2007 Location: Exeter, Devon, UK. Posts: 30	RA17W where to start Hi all Ive just finished my AR88D Now Its time to have ago at my Racal Ra17w Is there anything I should look out for before I power it up. Plus Its full of hunts metallished paper capacitors, so would it be best to replace these on sight. Just downloaded service a manual and removed covers so far Cheers Pete

24th Apr 2010, 11:54 pm	#2
AlanBeckett Rest in Peace Join Date: Dec 2008 Location: Burton upon Trent, East Staffordshire, UK. Posts: 1,686	Re: RA17W where to start My B40C, which predates your RA17, is riddled with metalised paper capacitors. As far as I can tell, they all work beautifully Alan

25th Apr 2010, 12:06 am	#3
MikeTheBrewer Retired Dormant Member Join Date: Apr 2010 Location: Lincoln, UK Posts: 3	Re: RA17W where to start Hi Pete, I have the RA17L, never had any probs with the capacitors, although if you find you have low signal strengths the anode and screen bypass caps are often suspect, especially in the RF and demodulator/AGC areas. Have you had any re-alignment probs with your AR88D ? I read up on it and it seems a bit of a challenge ( mine is still on the bench with low sinals on one band only..the others are dead. Mike.

25th Apr 2010, 12:39 pm	#4
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: RA17W where to start Please start a new thread regarding AR88 alignment. This one is about RA17Ls __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

26th Apr 2010, 11:37 am	#5
XTC Retired Dormant Member Join Date: Oct 2004 Location: Bristol, UK. Posts: 837	Re: RA17W where to start Start with the mains lead and connections. Make sure it's properly wired and fused and and the case is earthed. Next eyeball the whole set for replaced components and bodges. Look for anything obviously burned. If you find anything odd, investigate. Check the main smoothing cap for a bulging vent and reform it. The smoothing cap is hard to get at. Check that the crystal is a 1MHz one. It probably is, but if you assume that and it isn't, it's a phenomenal waste of time. Power the set up gently through a lamp limiter and check that the voltages are what you expect. Make sure the audio section works. When that works, go to the IF section and set it up as per the instructions. The caps don't seem to cause many problems. You'll almost certainly find a lot of resistors which have gone O/C or hopelessly high. According to this http://www.recelectronics.demon.co.uk/ra17.htm The RA17W is a minor variant of the RA17L with different IF bandwidths. As for mechanical problems, an obvious one is the film scale roller. It tends to stick and a flat wears on the roller. This is not good for the film scale and not the way it should be. You haven't got much option but to press the roller and bearings out and get a replacement roller machined up. If the bearings are rusted and grotty and don't respond to good clean and lubrication, they are probably standard parts. If you are in luck you'll see the roller turn easily with the slightest movement of the film scale and the roller will show no signs of flats. Pete.

26th Apr 2010, 6:49 pm	#6
morecider Retired Dormant Member Join Date: May 2007 Location: Exeter, Devon, UK. Posts: 30	Re: RA17W where to start Hi Thank you all for the advice/tips now its sat on me bench with a few more resistors to check Then hopefully ready for the big switch on this weekend so fingers crossed Cheers pete

8th Jun 2010, 4:53 pm	#7
morecider Retired Dormant Member Join Date: May 2007 Location: Exeter, Devon, UK. Posts: 30	Re: RA17W where to start Hi All What a nightmare of a project maybe bit off more than i can chew I have now got the output stage working now Both 1st/2nd VFOs and IF had high/burnt out resistors etc so no more smoke V24 replaced cv464 but still can not pick up anything but hash noise any ideas where to go from here Please Cheers pete

8th Jun 2010, 7:08 pm	#8
RobinBirch Hexode Join Date: Apr 2003 Location: Cotswolds, UK. Posts: 465	Re: RA17W where to start What do you have in the way of test gear? You won't be able to do this without a decent signal generator and one of the filter chains needs a good wobbulator. I haven't got the manual to hand but in essence work through backwards from the AF to the RF. If you get stuck I'll dig the manual out but there are many people on this site who have been down this path who can help. Robin

14th Jun 2010, 9:35 am	#10
cougar_lou Tetrode Join Date: Dec 2007 Location: Melbourne, Australia Posts: 60	Re: RA17W where to start Greetings to all. If anyone seriously believes they can restore any RA17 variant to correct working order WITHOUT replacing the dreaded Hunts paper capacitors then they are dreamers of the first order! Measure the leakage current of any of these dreadful things with 350Volts applied and you will soon see what I mean.Sure,you can have leaky cathode bypass capacitors but these will continue to fall below acceptable limits. Don't fool yourseleves,replace all these monsters,after all,how many times do you want to dismantle a 17,especially the firt and second VFOs? Brian G.

14th Jun 2010, 10:22 am	#11
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: RA17W where to start I'm not familiar with these sets, but the original post describes the capacitors as metallised paper. This could mean capacitors with a paper dielectric housed in a metal can. I've restored some military gear containing such capacitors and they were in excellent condition with hardly any electrical leakage. On the other hand if metallised paper means waxies replace them all. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

14th Jun 2010, 11:27 am	#12
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,518	Re: RA17W where to start I have an RA17L part way through restoration, and so far have only had to replace faulty resistors (and not too many of those either) The caps that are fitted to these are indeed Metallised Paper - and are utterly reliable in my experience - the only "waxies" I have found on mine were acting as mains input filter caps - they only lasted a few moments once power had been applied! Seems that RA17s are addictive - I've just purchased two more! Cheers Sean __________________ Engineers make things work and have spare bits when finished

5th Jul 2010, 12:06 am	#13
amornummi Triode Join Date: Mar 2008 Location: Huddersfield, West Yorkshire, UK. Posts: 45	Re: RA17W where to start I have repaired many RA17's. Two faults have been the tiny tubular 0.005 caps. One stopped the 1 meg oscillator going. The other was in the 1.6 meg if in a 117, open. Caused 10 db low gain. A pig to find. If you really must do something, check the ones on the agc line. 10 megohm is ok as there is 470k to ground and 20 meg pulling up to HT! Last edited by Darren-UK; 5th Jul 2010 at 10:04 am. Reason: FPK.

21st Jul 2010, 2:44 pm	#14
Colinaps Pentode Join Date: Jul 2009 Location: Roxburghshire, UK. Posts: 196	Re: RA17W where to start If the set has been stored in a shed or garage, shove it in the airing cupboard for a couple of weeks. First job is to make sure the right valves are in the right holes - never overestimate the previous owners!!! Pull them and replace to give the contacts a wipe, ditto with the crystal. Look for puddles of wax on the bottom covers. I would change those that have left a puddle or are badly blackened and check the resistors in their associated circuits. Check the mains voltage taps. Run it up slowly either with a variac or series 100W bulb and once you have worked up the confidence to apply the mains directly and haven't seen any smoke, do a voltage check on the valve bases you can reach as per the manual. It will probably be running by now anyway. Give all the valves a wiggle to check for noisy contacts You'd be surprised how far off spec components can be, while still allowing the set to work comparatively well. The only duff caps I have ever seen (in the couple of dozen I have had my hands in) actually stopping the radio from functioning completely are the silver micas in the IF strip (C210, 211, 212) and occasionally those in the filter sections. You must have done all this by now anyway, unless you are remarkably patient - does she go? nudge nudge etc...

22nd Jul 2010, 5:02 pm	#15
saxmaniac Heptode Join Date: Oct 2007 Location: Birmingham, West Midlands, UK. Posts: 618	Re: RA17W where to start You really must have a very accurate signal generator capable of 40mc/s at least, plus a good scope and the manual is excellent, so if you want one I can PDF it to you, measure voltages, inject signals and measure as directed in the manuals, a lot of times stages can be isolated to narrow down faults The poisonus capacitors are any of the black Hunts paper ones, the cases are often cracked & open to air and they were all leaky 30 years ago! Other types I have found can be risked if you dont want a huge amount of work