The Craftmans Shop > New from Old
Racal RA17 re-born : A trip down Memory Lane
awemawson:
So I'm glad to be able to report that Ian has agreed to breathe his magic over the RA137a-1 LF converter which undoubtedly needs the same attention to the aged capacitors and resistors, and a bit of alignment - though it is a far simpler affair than the RA17 itself.
Up early this morning (as loads of family descending on us soon for Easter) and packed it up sandwiched between a pair of sheets of plywood hopefully to protect it from the ravages of couriers in transit. Awaiting collection on Tuesday after the Bank Holiday.
Pete.:
I can't imagine the hours that's gone into that refurb. I don't suppose there are many people about now who could even do it.
The before and afters look amazing, along with the comprehensive report.
awemawson:
Yes he turns out good work. :thumbup:
He enjoys what he does, similar to me titivating various bits of CNC machinery, and certainly if one didn't enjoy it it would be quite a slog.
awemawson:
Well I've been and gone and done it again :clap:
An RA218 independent side band adaptor for the RA17 turned up on eBay and I won it last night. These are fairly scarce these days so although this one is not in prime condition I grabbed it.
The RA218 makes interfacing RTTY (radio teletype) equipment a doddle, and since that is what got me into computers back in the 1970's it's a bit of re-living past experiences.
The RA218 contains some unusual glass enveloped crystals - the most rare of them - an 18 kHZ - SEEMs to be present, but the others are contained in a crystal oven so the pictures cannot tell me if indeed they are there. I can tell from the photos that two valves , VT11 & VT12, are missing from their screening cans, but they are only 12AT7's used as audio output stages for the upper and lower sidebands. 12AT7's are still easily available at sensible prices (amazingly RSComponents stock them !!!) unlike many other valves which have become trendy in the "pretentious audio" world!
This time I have totally cheated, and have arranged for the seller to send it directly to Ian who has again agreed to wave his wand over the unit. He has one of these adaptors in his own RA17 / RA117 set up, but when he got it that rare 18 khz crystal was missing and he is running on a jury rig of a different crystal and a TTL divide chain!
So that's two RA17 adaptors from me on his 'to do' list :ddb:
seadog:
12AT7's are still easily available at sensible prices (amazingly RSComponents stock them !!!) unlike many other valves which have become trendy in the "pretentious audio" world!
Call them an ECC81, plate the legs gold and put the name Mullard on the envelope and you are talking silly money.
I sold 5 untested, other then the heaters, mixed ECC valves in 2015 - £50 :beer:
They came in a mixed box that I bought from a car boot for £15. I must have taken well over £100 out of that box tp date :thumbup:
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