UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Restoration73 · 24th May 2021, 1:22 pm

The Callins were also used by Thorn - if in doubt change on sight. Fot the RF/IF transistors
the AF114-117 were replaced bt the smaller AF124-127 which are still around.
The AC127 audio NPN has equivalents AC176 and AC187. The PNP complement for
those is AC188. Audio output transistors fail if the quiescent current is too high or
thermal runaway occurs so check the current with the volume set to zero.

24th May 2021, 1:22 pm	#21
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Masteradio D517/VHF Skymaster The Callins were also used by Thorn - if in doubt change on sight. Fot the RF/IF transistors the AF114-117 were replaced bt the smaller AF124-127 which are still around. The AC127 audio NPN has equivalents AC176 and AC187. The PNP complement for those is AC188. Audio output transistors fail if the quiescent current is too high or thermal runaway occurs so check the current with the volume set to zero.