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 11th Sep 2021, 9:06 am   #1
tinkera123
Triode
 
Join Date: Nov 2019
Location: Melbourne, Victoria, Australia
Posts: 16
Default Marconi R1155A refurb

Hi all,
I have eventually got back to this radio and starting to refurb.
One question for now ..... RF Frequency range coils L4, L5 and L6 are capacitatively tuned by C57, C58 and C59 which are located separately from the Coils.
So what are the large black slotted discs(??) on top of the Coils? They look like the tops of tuning slugs, but these Coils aren't tuned this way ... hence my query.

Thanks,
Ian
tinkera123 is offline  
Old 11th Sep 2021, 9:49 am   #2
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
Default Re: Marconi R1155A refurb

It's a while since I had on of these , but I suspect they are ceramic trimmers, could be wrong , Mick.
vinrads is offline  
Old 11th Sep 2021, 12:40 pm   #3
G4XWDJim
Octode
 
G4XWDJim's Avatar
 
Join Date: Oct 2008
Location: Littlehampton, West Sussex, UK.
Posts: 1,465
Default Re: Marconi R1155A refurb

They're cores, big ones to adjust at the low frequency end of the lower frequency bands.

You can see in the photo that they are pretty big iron dust or ferrite, I don't know which but the Bakelite screw thread is often jammed and hard to turn. They're easy to dismantle though and free off. I don't think they need to be moved much. Hope this helps

Jim
Attached Thumbnails
Click image for larger version

Name:	55 - 1.jpg
Views:	143
Size:	31.8 KB
ID:	241055   Click image for larger version

Name:	55 - 1 (1).jpeg
Views:	133
Size:	38.5 KB
ID:	241056  

Last edited by G4XWDJim; 11th Sep 2021 at 12:56 pm.
G4XWDJim is offline  
Old 12th Sep 2021, 12:48 am   #4
tinkera123
Triode
 
Join Date: Nov 2019
Location: Melbourne, Victoria, Australia
Posts: 16
Default Re: Marconi R1155A refurb

Thanks Jim and Mick,
Okay, that makes sense ... I will add a Note to my circuit diagram.
Tuning cores/slugs have caused me much grief in the past ... shattered cores, cores stuck to wax paper formers by possum pee etc etc ...
I always like to do a full re-alignment with any refurb, so I will get these moving again before I go too much further.
Cheers,
Ian
tinkera123 is offline  
Old 17th Sep 2021, 1:24 am   #5
tinkera123
Triode
 
Join Date: Nov 2019
Location: Melbourne, Victoria, Australia
Posts: 16
Default Re: Marconi R1155A refurb

Mmmm ... I have the L6 Coil apart as per photos posted by Jim. I am not keen to apply any force to the actual Core itself as I am not sure how it is connected to the threaded part. The threaded section has been covered in Varnish(??) from the top, and has no doubt seeped down into the thread.

I am assuming that the black top plate and threaded section of the Core are Bakelite ... ??

Is the best approach to try to soften the Varnish?? With what??

At the moment, I have applied reasonable force ... not at max effort just yet, but I don't wish to stuff this up.

Thanks,
Ian
tinkera123 is offline  
Old 17th Sep 2021, 9:05 am   #6
G4XWDJim
Octode
 
G4XWDJim's Avatar
 
Join Date: Oct 2008
Location: Littlehampton, West Sussex, UK.
Posts: 1,465
Default Re: Marconi R1155A refurb

The varnish is shellac I think which should soften if soaked in meths. I've found that they've usually cracked free once they're dismantled. Good luck.

Jim
G4XWDJim is offline  
Old 18th Sep 2021, 8:58 am   #7
tinkera123
Triode
 
Join Date: Nov 2019
Location: Melbourne, Victoria, Australia
Posts: 16
Default Re: Marconi R1155A refurb

Hi Jim and others,

I had the L6 thread soaking in Mineral Turps all yesterday and last night .... and this morning the Core moved with a bit more force ... all good now. I have L5 thread soaking in Meths now.

However, the Ferrite (??) slug had separated from the Core thread. In case this is helpful to some-one else, I have tried to attach a photo ...

Thinking ahead, I checked the Alignment procedure in the Manual A.P. 2458A Vol I Chap 2, para 121 - 125. This is not a complete Alignment procedure ... missing IF strip and Low frequency adjustments etc.. I can do this without it, but I would prefer to use the full official procedure. Can anyone direct me to such a write-up please ...?

Cheers,
Ian
Attached Thumbnails
Click image for larger version

Name:	Marconi R1155_L5 Tuning Core_resized.jpg
Views:	77
Size:	30.2 KB
ID:	241560  
tinkera123 is offline  
Old 19th Sep 2021, 9:43 am   #8
G4XWDJim
Octode
 
G4XWDJim's Avatar
 
Join Date: Oct 2008
Location: Littlehampton, West Sussex, UK.
Posts: 1,465
Default Re: Marconi R1155A refurb

There’s more info in the AP 1186 but whether it will be what you need I can’t remember not having looked at it for a long time. You might get another reply from someone on here who has that particular Air Publication.

Jim
G4XWDJim is offline  
Old 19th Sep 2021, 12:57 pm   #9
wave solder
Hexode
 
wave solder's Avatar
 
Join Date: Feb 2007
Location: Chesterfield, Derbyshire, UK.
Posts: 481
Default Re: Marconi R1155A refurb

When I restored my 1155 a I tried everything to free up some of the slugs in the inductors, I used the correct tools for the job too but trying to remove them caused more harm than good so I left the rest of them alone. Luckily the alignment did not seem too bad when I had finished it.
wave solder is offline  
Old 26th Sep 2021, 12:46 am   #10
tinkera123
Triode
 
Join Date: Nov 2019
Location: Melbourne, Victoria, Australia
Posts: 16
Default Re: Marconi R1155A refurb

Hi all,
An update ... All 3 tuning cores L4, L5 and L6 were jammed by Shellac (Varnish) which had seeped down to the 6th or 7th Thread. One Bakelite threaded section cracked when applying pressure .... two Ferrite/Iron slugs had separated from their Bakelite threaded parts. I used Meths and Mineral Turps to soften the Shellac (took a few days) and a home-made Dental pick to clean out all the muck in threads. The three Cores are now re-assembled and rotating freely. Slow and fiiddly work ... and care needs to be taken when re- gluing the two parts.
Most of the DF circuitry had been removed before I acquired this radio ... lots of snipped, hanging loose wires, cracked wires, wires rubbing on other components etc etc.. Much of this is sorted out, but I'm sure there will be more surprises.
I have got the Main Tuning knob/dial working correctly. All tuning adjustors (L's, C's, Filter, BFO) are free, except for the IF which I haven't tackled as yet.
Still a heap to do ...
Cheers, Ian

Last edited by tinkera123; 26th Sep 2021 at 12:51 am.
tinkera123 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 4:50 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.