|
Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
|
Thread Tools |
9th Jan 2019, 4:50 pm | #1 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
AR88 Tempted as I am!
Got this 50kG of metal on my bench after it has had a 15 years or so rest.
I remember back then carrying it myself, alas no more and last time running it brought in the new year. Very tempted as it worked then and no oily caps leaking (oil) to run it gently up on the variac. It goes of course against what I advise everyone else to do having said that. I will not ask for a show of hands either way. No doubt some would say go for it with careful monitoring. Also, is it 2 neons in series that protect the sound transformer? I have searched quickly to no avail.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
9th Jan 2019, 5:10 pm | #2 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
|
Re: AR88 Tempted as I am!
Let us know how it goes...
__________________
David, G4YVM. |
9th Jan 2019, 5:19 pm | #3 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,510
|
Re: AR88 Tempted as I am!
Check the capacitor between the anode of the audio output valve and ground. It has a tendency to go leaky and kill the output transformer.
Andy |
9th Jan 2019, 5:28 pm | #4 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
Re: AR88 Tempted as I am!
Thank you Andy,very good point.
Neons will not save it from that capacitor.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
9th Jan 2019, 5:42 pm | #5 |
Octode
Join Date: Jun 2013
Location: Fleet, Hampshire, UK
Posts: 1,764
|
Re: AR88 Tempted as I am!
I believe its 2 Neons in parallel, least that's what I did with mine. This thread reminds me, I must get mine back out for another going over...
|
9th Jan 2019, 6:37 pm | #6 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
|
Re: AR88 Tempted as I am!
I think the mod was move capacitor from Anode to Ground to become Anode to B+ instead.
Then Neons (2 for more clamping effect) across capacitor might protect it somewhat on very loud AF peaks - or? |
9th Jan 2019, 8:14 pm | #7 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
|
Re: AR88 Tempted as I am!
On my 88 "that capacitor" was actually two smaller flat brown cased capacitors in parallel.
I replaced it by a modern 400V-rated MKT type. Also on mine after a period of disuse I found that one of the big brown ceramic resistors in the bias network went open-circuit. I replaced all of them with new square ceramic 'coffin' resistors for enhanced reliability. |
10th Jan 2019, 12:54 am | #8 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
|
Re: AR88 Tempted as I am!
If original, change C117, 118, 119, 122 anyway (as mentioned), then lamp limiter in case things like the C96, 97, 98 block aren't what they were?
Still a marvellous radio, just try and imagine how much it would cost to make now! |
10th Jan 2019, 9:11 am | #9 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
Re: AR88 Tempted as I am!
Thank you all again.
Yes,how much now indeed to produce.Rough guess £5000.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
12th Jan 2019, 9:32 pm | #10 |
Retired Dormant Member
Join Date: Jan 2017
Location: Brighton, East Sussex, UK.
Posts: 1
|
Re: AR88 Tempted as I am!
I bought an AR88 and thinking I had made a mistake when it came to moving it! Now I have it all working I really like it and it was worth the effort. In the 1940s era it must have been highly regarded.
|
12th Jan 2019, 11:42 pm | #11 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
|
Re: AR88 Tempted as I am!
Seconded! It must have been an excellent tool for its operators when it came out, as with so many things that have reached the halls of fame it hit a sweet spot of capability by combining various developments of the era rather than having one single outstanding feature. Polystyrene coil formers for low loss and high stability, voltage stabilisation, lots of IF tuned circuits, switching between high-ratio and low-ratio tuning gangs for good bandspread and consistent gain, low-noise RF pentodes with good HF capability and sturdy, low-microphony construction all came together to make it among the outstanding mass-produced performers of the era.
It's always a bit sobering to think that without the catastrophe of WW2, only a few lucky US amateurs might have come to appreciate it, though. |
13th Jan 2019, 1:37 am | #12 |
Dekatron
Join Date: Jan 2006
Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex.
Posts: 5,814
|
Re: AR88 Tempted as I am!
See my rusbriges auction post re the AR88.
Dave |
13th Jan 2019, 1:19 pm | #13 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
Re: AR88 Tempted as I am!
It is still on the workshop bench awaiting a careful check before a variac wake up call.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
13th Jan 2019, 2:22 pm | #14 |
Pentode
Join Date: May 2010
Location: Wick, Scotland, UK.
Posts: 227
|
Re: AR88 Tempted as I am!
I know how you feel
I have three ar88's in my shed, just can not lift them now and too heavy to post, what does one do?, break up for people wanting parts? same with two R107's I have.again too heavy now for me to handle. MM0HDW |
13th Jan 2019, 3:22 pm | #15 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
Re: AR88 Tempted as I am!
Do not break up, advertise collection only. Yes, I also have an R107.
I collared a pal who came over to lift with mine.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
14th Jan 2019, 11:40 am | #16 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
|
Re: AR88 Tempted as I am!
I bought a sack truck. The modern ones on eBay are a bit flimsy, but I found a good S/H metal one cheaper. Invaluable for us oldies!
|
14th Jan 2019, 11:56 am | #17 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
Re: AR88 Tempted as I am!
Yes Bill, I thought about one of those too. Though you still need to lift on to a bench, possibly an engine hoist is about right.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
16th Jan 2019, 2:00 pm | #18 |
Pentode
Join Date: May 2010
Location: Wick, Scotland, UK.
Posts: 227
|
Re: AR88 Tempted as I am!
Yes, very good radios but need to be younger and fitter than I am to move these around
I need the space for other easier lifted projects collection only ?? I am in wick north Scotland so quite a journey. The R107's can be dismantled as built in three modules. the AR88's are more of a problem but they have to go. |
16th Jan 2019, 2:32 pm | #19 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
|
Re: AR88 Tempted as I am!
Try putting them out in the offered bit of the forum.Not sure what or if you are asking for them?
It just could save them from being broke up. Courier on a pallet I guess could be £50 plus but you never know who might be tempted.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
16th Jan 2019, 3:16 pm | #20 |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,196
|
Re: AR88 Tempted as I am!
I agree that, for those of us of pensionable age, an AR88 is a 'two-man lift' - its width is part of the problem that make it difficult to get a decent hold.
I recently transferred my own AR88 (unaided) from a shelf in my workshop to a table in another shed some 30 yards away. With care, I found that my wheelbarrow could do the move as long as the set was located centrally in it to avoid the risk of tipping. Actually getting the set in and out of the barrow just needed patience (and blankets for mechanical protection). I found that I could pretty readily lift one end of the set at a time so that by finding tables, chairs, stools etc of different heights, I could 'walk' it progressively and safely from its shelf into the barrow, down to the floor, and up again to its new table location. So far, my back hasn't suffered any ill effects! Martin
__________________
BVWS Member |