UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Amateur and Military Radio

Notices

Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

Closed Thread
 
Thread Tools
Old 29th Jan 2018, 11:03 pm   #1
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default AR88 S.No. 000726

Hi All
I have acquired a nice working AR88.
Can anyone tell me did they have a gloss black finish on the front panel?
I had an LF version 50 years ago and can't quite remember!!

I said it works but have still to bottom out all the problems that may exist.

Two problems so far,
1. Band 2 Ant peak control dose very little to signals.
2. Band 6 Ant peak control produces birdies when peaking to maximum.

Problem 1. Turns out to be a melted L3/L4 Former, guess someone forgot to switch the LG300 to the Aerial hi hi. It receives signals ok but no peaking, tried to trim L3/L4 but it wouldn't move It looks around 3/8" shorter than other similar former's. Dont think this is a problem apart from getting it out, which looks possible and I will make a new former hoping the core is still intact.

Problem 2. Will look at this after sorting problem 1! Unless anyone has any ideas?


Thanks in advance

Ian G4GIR
G4GIRLX0 is offline  
Old 29th Jan 2018, 11:31 pm   #2
Silicon
Nonode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,152
Default Re: AR88 Sno 000726

I have an AR88D with black wrinkle finish and another with a smooth satin finish.

The smooth satin version looks like it has the original wiring and components.
It has the all yellow wave band scale on the left hand side.

Some receivers were rewired and overhauled and may have had the front panel resprayed.
Silicon is offline  
Old 31st Jan 2018, 8:20 am   #3
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Hi Thanks for the info, wonder what the Sno's are? The reason I asked about the finish is that, with this one you could have assumed it was a mat/satin maybe finish. The panel was removed and sprayed with a foam cleaner which showed I guess 70 plus years of grime running off, revealing a vaguely shiny finish, the rear of course is definitely mat finish. Well a drop of TCut and it looks like a new unit! The knobs cleaned and re whitened and the panel engraving re filled with white paint.

As for the other problem, managed to make a new L3/L4 and now it operates as expected. Have included a picture of the melted core and the new one. The other problem (birdies) appears to have disappeared, but plenty more testing to do.

73

Ian G4GIR
Attached Thumbnails
Click image for larger version

Name:	IMG_20180130_093745939.gif
Views:	166
Size:	161.2 KB
ID:	156473   Click image for larger version

Name:	IMG_20180130_144935744.gif
Views:	164
Size:	161.9 KB
ID:	156474  
G4GIRLX0 is offline  
Old 31st Jan 2018, 9:14 am   #4
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
Default Re: AR88 Sno 000726

Great job of that coil. Check the screen feed reses for going high 33K I think. Also the bathtub oil filled caps leak, could be PCB so take care. Easy to re stuff.

And then there is a mod putting 2/3 neons across the fragile sound o/put tx.

Plenty of info on this forum.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S
HamishBoxer is offline  
Old 31st Jan 2018, 10:57 am   #5
PsychMan
Octode
 
PsychMan's Avatar
 
Join Date: Jun 2013
Location: Fleet, Hampshire, UK
Posts: 1,764
Default Re: AR88 Sno 000726

Earliest receivers had the gloss enamel panel , yellow dial, and engraved lettering rather than silk screened. Also a some subtle differences like the labelling for the main tuning dial shows "Tuning" above the dial, and later models show "Tuning" and "Control" either side.

Henrys Radioblvd web site has lots of interesting info, including some serial number info. If yours has the yellow dial, gloss panel etc, AND that serial number, yours could be very early indeed. Earliest models also lack the 600ohm output on the rear

http://www.radioblvd.com/ar88.htm
PsychMan is offline  
Old 31st Jan 2018, 3:31 pm   #6
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Thanks all for the comments.

Yes I am slowly sifting the Archive info, so far incorporated the link in the Trans position. Plenty still to do. As for the bathtub cap's, Is that the Orange gunk around the terminals that I see on quite a few of them?

Ok on the Paint finishes, I am glad to hear that early ones weree gloss finish! Hated to have ruined an original. Yes that about describes this one, no 600 Ohm sockets albeit the holes for it are there, yellow dial, engraved front panel and only has Tuning above the Tuning knob. It does have an S Meter but it is not orignal.

The set belonged to the now SK G3IIY and with it iv'e been given a picture showing it in G3IIY's shack, also came with original data books and possibly original speaker although that is crackle finish. The person dealing with the estate also licensd who knew G3IIY very well from childhood days said he bought the AR88 back from Germany!! So probably not a lot of history of it before then?

Thanks again and will surely be asking more questions Hi Hi.

73

Ian G4GIR
G4GIRLX0 is offline  
Old 31st Jan 2018, 4:34 pm   #7
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Thanks for the link David, very useful. Now I see what the orange gunk is!!

Cheers

Ian G4GIR
G4GIRLX0 is offline  
Old 31st Jan 2018, 8:38 pm   #8
dodgy-dxer
Heptode
 
dodgy-dxer's Avatar
 
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
Posts: 611
Default Re: AR88 Sno 000726

Good to see you are spending your retirement time well OC

Sold my '88 many years ago as you know

73 and 88 to Jean

Fred
dodgy-dxer is online now  
Old 31st Jan 2018, 8:44 pm   #9
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Hi Fred

Don't know how I find the time!! Do you remember where I got the AR88LF from?? Something tells me it was Woburn. All ready for Bouvet here on WARC bands.
Cheers all the best to the family

73
Ian
G4GIRLX0 is offline  
Old 2nd Feb 2018, 11:00 am   #10
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Hi all

Spent yesterday checking replacing R's, 10 of them were replaced worst culprit was a 2.2M reading 12.7Meg.

Have ordered replacements for all Micamoild and Bathtub Caps. Which brings me to my next question or two.

In the link http://www.radioblvd.com/ar88.htm It states changing all 4700, 2200 &3300 Micamold caps, there are no 2200 or 3300 pF shown in the component list I have,however all higher values listed 15500, 2700, 2000 & 3900 pF are of the Lozenge or a Domino 6 dot type with Solar Made in USA on the rear, can I assume these are not in the same category as the Micamolds and don't need replacing? unless the value is significantly out?

I also checked the temperature rise of the filter block and bathtub caps, the filter block didn't change after 12 hours of operation and only C79,84,92 and C56,76 & 93 bathtubs got warm. Is it worth changing the filter block caps?

That's enough questions for now and work for a few days!

Thanks again.

73 Ian G4GIR
G4GIRLX0 is offline  
Old 2nd Feb 2018, 11:56 am   #11
turretslug
Dekatron
 
turretslug's Avatar
 
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
Default Re: AR88 Sno 000726

The 4.7nF Micamoulds are evil in both character and location and are worth winkling out, the receiver deserves it to realise its capability. If the filter block isn't leaking (electrically and physically), it's tempting to keep it as it is- but consider fitting a low-value fuse before the first reservoir section as who knows when a 75-year old component might fail and imperil the mains transformer. I don't know what the voltage withstand rating of 20mm fuses is, but I definitely feel more comfortable with 1.25" (32mm) types. I made a bracket secured by the 3x 250nF bathtub securing screws with 4x 1.25" fuse-holders for comprehensive peace of mind. Perhaps the Radioboulevard site meant the 2.7nF Micamoulds associated with the 1st AF amp stage?
turretslug is offline  
Old 2nd Feb 2018, 12:09 pm   #12
PsychMan
Octode
 
PsychMan's Avatar
 
Join Date: Jun 2013
Location: Fleet, Hampshire, UK
Posts: 1,764
Default Re: AR88 Sno 000726

The lozenge ones, if that's the pink RCA ones, every one I removed from my set tested absolutely fine, as did the solar ones from memory, I regretted removing the ones I did, though one was visibly cracked. I think I used 3nf for the 3300pf, and 2nf for the 2200s on the basis its within 10%. That said my receiver is still not there performance wise, maybe I will live to regret that!

On my original model I replaced the whole block with a fabricated steel box with new parts hidden inside. Despite heating, boiling, and a few other attempts I could not extract the contents for restuffing, though many have succeeded in that.
PsychMan is offline  
Old 2nd Feb 2018, 3:08 pm   #13
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Thanks both
Changed 5 of the Micamolds so far, all ranging from 7.9 - 11.1nF as you say some are a pig to get at but not impossible! so far. Thanks for the tips on the Pink ones and Solar ones, will consider removing and testing. Yes that could be the reason for the different values, fortunately the only Micamolds are the 4.7nF's, Will fit a fuse before the first reservoir cap makes good sense. Think I am not going to open those Bathtubs seems to much hassle with the PCB's etc.None of them appear to be leaking, so will leave them fitted and fit new caps on tags beside them.

Back to the grind 5 more Micamolds to remove.

73

Ian G4GIR
G4GIRLX0 is offline  
Old 2nd Feb 2018, 4:49 pm   #14
turretslug
Dekatron
 
turretslug's Avatar
 
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
Default Re: AR88 Sno 000726

Generally, I tend to utility rather than appearance with overhaul, and don't like digging around in old capacitors from long before RoHS and the like were even a twinkle in the regulators' eyes- but there's no denying that the bathtubs are a significant part of the character and appearance of US-made kit of this era. I've heard that the military dispose of old ammunition in an armoured incinerator, collecting the brass casings and expended rounds once the racket stops- perhaps a similar apparatus could be devised for bathtubs.... (Only joking!)
turretslug is offline  
Old 2nd Feb 2018, 5:43 pm   #15
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: AR88 Sno 000726

I'm a "form follows function" type at heart - my safe-and-reliable solution to AR88 bathtubs is to delete them - and in place etch a suitable bit of double-sided FR4 to fit over the space (on short standoffs) where the bathtubs once lived, populate with 'turret tags' and solder in 'modern' Philips Mustards or commodity yellow MKT caps.

After all, the SRBP-and-tags approach worked well enough for the guys at RCA when specifying the high-power resistors in the bias network. . . .
G6Tanuki is offline  
Old 2nd Feb 2018, 10:19 pm   #16
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Hmm that's given me food for thought, my brother has a cnc mill I am sure he would like a new project a bit of aluminium stock, can also engrave them like original and a cnc lathe, looks like I need to be kind to him!!
Or back to plan B!
Cheers for the comments

73

Ian G4GIR
G4GIRLX0 is offline  
Old 7th Feb 2018, 9:34 pm   #17
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Things are progressing well, decided to re stuff the bathtubs, removing the backs by milling them out, not to much of a messy job.
As the filter block is not getting warm at all, I decided not to replace them. Rx is drawing around 84mA at the 1st reservoir cap so fitted a 100ma fuse.

Checking the Plate Screen and Cathode voltages as per the manual all are ok , except for V10 Plate 40 and V12 plate 30V, replaced both Plate resistors at V10 now getting 81V

But V12 Plate R's have gone High 178k, and of course they are inside T10. Does anyone have any tips before I tear it apart?

Thanks

Ian G4GIR
G4GIRLX0 is offline  
Old 8th Feb 2018, 11:30 am   #18
Keith
Heptode
 
Keith's Avatar
 
Join Date: Jan 2003
Location: Tewkesbury, Gloucestershire, UK.
Posts: 690
Default Re: AR88 Sno 000726

I found it possible to remove the backs of the bathtubs by drilling a small hole near one edge and simply "popping" them out using a screwdriver. Having removed the contents (using rubber gloves) it was very straightforward to fit 630V polypropylenes inside. Didn't bother to replace the backs as they are not visible.
__________________
Keith Yates - G3XGW
VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm
Keith is offline  
Old 9th Feb 2018, 4:43 pm   #19
G4GIRLX0
Retired Dormant Member
 
Join Date: Jan 2018
Location: Bedford, Bedfordshire, UK.
Posts: 16
Default Re: AR88 Sno 000726

Hi Keith
Yes I figured that way maybe possible I guess the solder just tears apart?.The milling away was straightforward and leaves a nice clean edge, as you say backs not refitted. As for T10, It came out easy enough with no surprises so replaced all the R's inside. Need to acquire an SSG to complete the job!.

73

Ian G4GIR
G4GIRLX0 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:36 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.