KB Kobra 305 TRF radio - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

crackle · 8th Apr 2016, 4:16 pm

A correction to the valve line up, it should have been 41MHL HL4 ML4 DW2.
I cant read my notes.

GeoffK · 8th Apr 2016, 4:33 pm

Good pictures, interesting that the green and white wires from the large coil look quite modern compared with the rest of the wiring, some of the rubber covered wiring could be at risk of shorting inside the cableform. C7 and C9 could be replaced with new capacitors, keeping the disconnected originals in place.

crackle · 8th Apr 2016, 4:48 pm

Oh I should have mentioned that, there was some rubber wiring that had crumbled, including the wiring for the wander plugs and to the adjustable coupling coil inside the large coil pack. These had to be replaced, so yes they do look a bit clean and modern.

The rest of the wiring was cloth covered, much of it was laced up neatly into a wiring loom, and this has been left in place.
I had thought that the shorting wiring in the coil pack may have contributed to the Speaker coil burning out. That was before I found out that the speaker coil was across the HT.
Mike

P.S.
C7 & C9 are mica and were left in place. or have I made a mistake on a drawing somewhere.
The metal can caps C10 & C11 tested OK on a leakage test so have been left in place.

Paul Stenning · 8th Apr 2016, 8:03 pm

Quote:

Originally Posted by crackle

A correction to the valve line up, it should have been 41MHL HL4 ML4 DW2.
I cant read my notes.

Mike sent me a replacement document correcting this error which is now in post #16.

8th Apr 2016, 4:16 pm	#21
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: KB Kobra 305 TRF radio A correction to the valve line up, it should have been 41MHL HL4 ML4 DW2. I cant read my notes.

8th Apr 2016, 4:33 pm	#22
GeoffK Heptode Join Date: Mar 2016 Location: Essex, UK. Posts: 602	Re: KB Kobra 305 TRF radio Good pictures, interesting that the green and white wires from the large coil look quite modern compared with the rest of the wiring, some of the rubber covered wiring could be at risk of shorting inside the cableform. C7 and C9 could be replaced with new capacitors, keeping the disconnected originals in place.

8th Apr 2016, 4:48 pm	#23
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: KB Kobra 305 TRF radio Oh I should have mentioned that, there was some rubber wiring that had crumbled, including the wiring for the wander plugs and to the adjustable coupling coil inside the large coil pack. These had to be replaced, so yes they do look a bit clean and modern. The rest of the wiring was cloth covered, much of it was laced up neatly into a wiring loom, and this has been left in place. I had thought that the shorting wiring in the coil pack may have contributed to the Speaker coil burning out. That was before I found out that the speaker coil was across the HT. Mike P.S. C7 & C9 are mica and were left in place. or have I made a mistake on a drawing somewhere. The metal can caps C10 & C11 tested OK on a leakage test so have been left in place. Attached Thumbnails Last edited by crackle; 8th Apr 2016 at 4:57 pm.