Hmv 2346 af115 - UK Vintage Radio Repair and Restoration Discussion Forum

vampyretim · 11th Oct 2018, 3:15 pm

Hi,

I'm repairing an HMV Radiogram. I've repaired the amplifier side and am now moving onto the radio. Neither F.M or A.M work. I'm not getting any emitter voltages across VT4 or VT5 so have taken out the transistors to test and I'm getting identical resistance in both directions of the junctions. The transistors are those horrible AF115's/AF116's. What do you guys replace these with?

Many thanks.

Boater Sam · 11th Oct 2018, 3:18 pm

Just about any germanium signal transistor. If you search here for AF117 replacements you will find pages of posts about substitutes for the Mullard AF11x series.

Herald1360 · 11th Oct 2018, 4:53 pm

For the VHF front end and IF, you need a passable RF transistor, not just any old Ge PNP.

AF124/5/6/7 are electrically though not physically identical but quite expensive now. Russian GT322B are also good electrically and somewhat cheaper, though the days of packs of 100 for £20 are no more......

vampyretim · 12th Oct 2018, 2:40 pm

Thanks guys.

Boater Sam · 12th Oct 2018, 4:49 pm

I have used AFZ12 amongst others with good results. The mixer/oscillator is usually the most fussy. Many RF transistors will work providing they are PNP with a good frequency rating, even some silicon transistors often work.
But why use silicon and risk having to adjust the bias when there is a lot of germanium still around?
What have you got in stock? Solder some longer leads onto the pcb and hook up a few odd ones to see if they work.
Sam.

paulsherwin · 12th Oct 2018, 5:14 pm

Search the forum, there are dozens of threads about this.

Replacement is usually straightforward with Ge and often with Si too. You need an Ft of 120MHz for the mixer and 20MHz for the IF amps, though higher ratings will obviously be OK too.

crackle · 12th Oct 2018, 5:29 pm

It seems the FM front end uses 2 BF160 transistors, these may be OK.
If you check out the service data available from up top then it gives the equivalent AF12x transistors. VT3 & 4 AF125, VT5 & 6 AF126.

Mike

11th Oct 2018, 3:15 pm	#1
vampyretim Heptode Join Date: Aug 2011 Location: Bristol, UK. Posts: 538	Hmv 2346 af115 Hi, I'm repairing an HMV Radiogram. I've repaired the amplifier side and am now moving onto the radio. Neither F.M or A.M work. I'm not getting any emitter voltages across VT4 or VT5 so have taken out the transistors to test and I'm getting identical resistance in both directions of the junctions. The transistors are those horrible AF115's/AF116's. What do you guys replace these with? Many thanks.

11th Oct 2018, 3:18 pm	#2
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Hmv 2346 af115 Just about any germanium signal transistor. If you search here for AF117 replacements you will find pages of posts about substitutes for the Mullard AF11x series.

11th Oct 2018, 4:53 pm	#3
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Hmv 2346 af115 For the VHF front end and IF, you need a passable RF transistor, not just any old Ge PNP. AF124/5/6/7 are electrically though not physically identical but quite expensive now. Russian GT322B are also good electrically and somewhat cheaper, though the days of packs of 100 for £20 are no more...... __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

12th Oct 2018, 2:40 pm	#4
vampyretim Heptode Join Date: Aug 2011 Location: Bristol, UK. Posts: 538	Re: Hmv 2346 af115 Thanks guys.

12th Oct 2018, 4:49 pm	#5
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Hmv 2346 af115 I have used AFZ12 amongst others with good results. The mixer/oscillator is usually the most fussy. Many RF transistors will work providing they are PNP with a good frequency rating, even some silicon transistors often work. But why use silicon and risk having to adjust the bias when there is a lot of germanium still around? What have you got in stock? Solder some longer leads onto the pcb and hook up a few odd ones to see if they work. Sam.

12th Oct 2018, 5:14 pm	#6
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: Hmv 2346 af115 Search the forum, there are dozens of threads about this. Replacement is usually straightforward with Ge and often with Si too. You need an Ft of 120MHz for the mixer and 20MHz for the IF amps, though higher ratings will obviously be OK too.

12th Oct 2018, 5:29 pm	#7
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Hmv 2346 af115 It seems the FM front end uses 2 BF160 transistors, these may be OK. If you check out the service data available from up top then it gives the equivalent AF12x transistors. VT3 & 4 AF125, VT5 & 6 AF126. Mike