Nagra III head changing - UK Vintage Radio Repair and Restoration Discussion Forum

barretter · 22nd Jun 2012, 10:54 am

I've just acquired a Nagra III and was wondering how easy/difficult it is to change the heads as I would like to install a half-track mono head in place of the full track mono it currently has, presuming that a suitable head can be obtained. Many thanks for any information.

Refugee · 23rd Jun 2012, 2:48 pm

Have a look at these.
https://www.vintage-radio.net/forum/...ad.php?t=83149
Let me know if they are any good to you.

barretter · 24th Jun 2012, 11:13 am

Well those are quarter track stereo and meant for a BSR deck so they're not really what I'm looking for, but thanks for the offer.

Refugee · 24th Jun 2012, 11:25 am

It was worth a look.

Radio Wrangler · 24th Jun 2012, 12:57 pm

Nagra/Kudeleski still seem to be on the go... unless they've done a quad/goodmans and become merely a brand of convenience.

Did they make their own heads, or did they use Bogen, I wonder?

David

TIMTAPE · 24th Jun 2012, 1:53 pm

Not sure if you could obtain a half track mono head. I doubt Nagra made them but a half track stereo head from the later Nagra 4 series might fit, wiring it for the top track only.

Assuming the III heads are physically the same as the IV series (and I'm not totally sure about that) it's not that hard to change them over. There are no wires to solder on the IV series as the heads have pins on the head's underside which plug into sockets on the machine.

The two adjustments are for head tilt and azimuth. All other settings are fixed.

Here's a photo of Nagra 4.2 stereo play head shown upside down. Note the four connecting pins at the rear for the signal.

barretter · 25th Jun 2012, 11:15 am

Thanks for that, Timtape. The next question is, I guess, is it possible to remove the head from the top as access from below is blocked the main motor. As you can't see in my photograph there is a screw in a tag attached to the headblock : do I unscrew that to extract the head? I only ask because I really don't want to foul this machine up.
I have the horrible feeling that once I get the head off that there will only be two holes for pins to fit into.
I was thinking of asking somebody like Summertone to make me a head for me : is that just wishful thinking?

TIMTAPE · 25th Jun 2012, 1:12 pm

As I said I'm no expert on the Nagra III. From looking at your photo, it looks as if the head mounting system was changed at the IV series which provided access to the central nut from above. No need to even open the machine up.

If half track is what you are after I'd suggest a better choice would have been a later model half track stereo unit, or even a mono model and swap the mono head for stereo. A lot easier than trying to modify a Nagra III machine, I'd suggest.

I believe too that the late 1950's Nagra III while a trail blazer in its day was limited by having to use germanium transistors. All the later models of course used silicon semis.

Anyway hopefully one of the real Nagra experts will chime in here to clarify.

barretter · 26th Jun 2012, 11:09 pm

I've had a closer look at the playback head and it has two wires from its base going through the chassis to an amplifier, so it's different to the IV series modular system as you said.

22nd Jun 2012, 10:54 am	#1
barretter Heptode Join Date: Jan 2006 Location: Todmorden, West Yorkshire, UK. Posts: 870	Nagra III head changing I've just acquired a Nagra III and was wondering how easy/difficult it is to change the heads as I would like to install a half-track mono head in place of the full track mono it currently has, presuming that a suitable head can be obtained. Many thanks for any information.

23rd Jun 2012, 2:48 pm	#2
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Nagra III head changing Have a look at these. https://www.vintage-radio.net/forum/...ad.php?t=83149 Let me know if they are any good to you.

24th Jun 2012, 11:13 am	#3
barretter Heptode Join Date: Jan 2006 Location: Todmorden, West Yorkshire, UK. Posts: 870	Re: Nagra III head changing Well those are quarter track stereo and meant for a BSR deck so they're not really what I'm looking for, but thanks for the offer.

24th Jun 2012, 11:25 am	#4
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Nagra III head changing It was worth a look.

24th Jun 2012, 12:57 pm	#5
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,903	Re: Nagra III head changing Nagra/Kudeleski still seem to be on the go... unless they've done a quad/goodmans and become merely a brand of convenience. Did they make their own heads, or did they use Bogen, I wonder? David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

24th Jun 2012, 1:53 pm	#6
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,971	Re: Nagra III head changing Not sure if you could obtain a half track mono head. I doubt Nagra made them but a half track stereo head from the later Nagra 4 series might fit, wiring it for the top track only. Assuming the III heads are physically the same as the IV series (and I'm not totally sure about that) it's not that hard to change them over. There are no wires to solder on the IV series as the heads have pins on the head's underside which plug into sockets on the machine. The two adjustments are for head tilt and azimuth. All other settings are fixed. Here's a photo of Nagra 4.2 stereo play head shown upside down. Note the four connecting pins at the rear for the signal. Attached Thumbnails

25th Jun 2012, 11:15 am	#7
barretter Heptode Join Date: Jan 2006 Location: Todmorden, West Yorkshire, UK. Posts: 870	Re: Nagra III head changing Thanks for that, Timtape. The next question is, I guess, is it possible to remove the head from the top as access from below is blocked the main motor. As you can't see in my photograph there is a screw in a tag attached to the headblock : do I unscrew that to extract the head? I only ask because I really don't want to foul this machine up. I have the horrible feeling that once I get the head off that there will only be two holes for pins to fit into. I was thinking of asking somebody like Summertone to make me a head for me : is that just wishful thinking? Attached Thumbnails

25th Jun 2012, 1:12 pm	#8
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,971	Re: Nagra III head changing As I said I'm no expert on the Nagra III. From looking at your photo, it looks as if the head mounting system was changed at the IV series which provided access to the central nut from above. No need to even open the machine up. If half track is what you are after I'd suggest a better choice would have been a later model half track stereo unit, or even a mono model and swap the mono head for stereo. A lot easier than trying to modify a Nagra III machine, I'd suggest. I believe too that the late 1950's Nagra III while a trail blazer in its day was limited by having to use germanium transistors. All the later models of course used silicon semis. Anyway hopefully one of the real Nagra experts will chime in here to clarify. Last edited by TIMTAPE; 25th Jun 2012 at 1:14 pm. Reason: extra thought

26th Jun 2012, 11:09 pm	#9
barretter Heptode Join Date: Jan 2006 Location: Todmorden, West Yorkshire, UK. Posts: 870	Re: Nagra III head changing I've had a closer look at the playback head and it has two wires from its base going through the chassis to an amplifier, so it's different to the IV series modular system as you said.