3.3k resistor or 4k coils? - UK Vintage Radio Repair and Restoration Discussion Forum

StephenMG · 27th Jun 2011, 1:20 am

Hello all, a quickie for the experts if I may.

I have a Tele 332 which I have already converted and a Tele 310 which I have just acquired and will convert shortly (assuming I can work out how!).

In converting the 332 I installed a 3.3k resistor to adjust the REN value in the usual way. However, I now have a number of 4k ringer units which I'm tempted to remove the 2k coils from and install them in my 332 (and the 310) in place of the original 500ohm units.

My question then is this. Is there any advantage in doing this, for example in the 'quality' or 'strength' of the ring, or does it not make any difference which method is used?

I quite like the idea of replacing the coils because it means there are fewer 'extra' components in the phone. That's offset by having non-original coils in the ringer of course but it seems a neater solution somehow.

So, are there any advantage or disadvantages to either method - extra resistor or swapped coils?

Thanks,
Mark

russell_w_b · 27th Jun 2011, 8:29 am

Try without the 3k resistor in any case - I've never had a problem! This depends on the inductive / capacitive load of other instruments on your line, though, and may or may not work at all locations.

A better ring will be obtained with the 2K bobbins (4K measured at d.c.), as they are dsigned to optimise the magnetic field. With a 3.3k resistor, you will drop approximately half your ringing voltage across the resistor (measured across resistor and bell-motor, and NOT including capacitor), which is wasteful, even though a meagneto bell will work down to about 8 or 9 mA.

StephenMG · 27th Jun 2011, 12:04 pm

Thank you very much Russell, that's exactly the sort of info I was after.

Quote:

Originally Posted by russell_w_b

A better ring will be obtained with the 2K bobbins...

This was the main reason for asking I suppose - my 332 rings satisfactorily but does sometimes sound the tiniest bit 'vague'. I was hoping that fitting the 2k coils would improve that and provide a more robust ring. You've convinced me that it's worth giving it a try.

Thanks again,
Mark

russell_w_b · 27th Jun 2011, 12:22 pm

Quote:

Originally Posted by StephenMG

You've convinced me that it's worth giving it a try.

You've nothing to lose - it's an easy mod to do (and revert, if necessary). Are your gongs adjusted so the hammer just strikes them and bounces off?

StephenMG · 27th Jun 2011, 2:54 pm

I'm confident the gongs are fine - I've spent ages (to the point of obsession!) tinkering with them to get them as good as I can.

I still feel as though the ring could be stronger though as it is sometimes slightly hesitant. I'm the only one in the house who notices it and everyone else thinks I've some kind of OCD where this is concerned!

I'm certainly going to give the 2k coils a go. As you say it's easy and quick to do and there's nowt to lose!

Thanks again,
Mark

27th Jun 2011, 1:20 am	#1
StephenMG Retired Dormant Member Join Date: Jul 2010 Location: South Wales, UK. Posts: 15	3.3k resistor or 4k coils? Hello all, a quickie for the experts if I may. I have a Tele 332 which I have already converted and a Tele 310 which I have just acquired and will convert shortly (assuming I can work out how!). In converting the 332 I installed a 3.3k resistor to adjust the REN value in the usual way. However, I now have a number of 4k ringer units which I'm tempted to remove the 2k coils from and install them in my 332 (and the 310) in place of the original 500ohm units. My question then is this. Is there any advantage in doing this, for example in the 'quality' or 'strength' of the ring, or does it not make any difference which method is used? I quite like the idea of replacing the coils because it means there are fewer 'extra' components in the phone. That's offset by having non-original coils in the ringer of course but it seems a neater solution somehow. So, are there any advantage or disadvantages to either method - extra resistor or swapped coils? Thanks, Mark

27th Jun 2011, 8:29 am	#2
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	Re: 3.3k resistor or 4k coils? Try without the 3k resistor in any case - I've never had a problem! This depends on the inductive / capacitive load of other instruments on your line, though, and may or may not work at all locations. A better ring will be obtained with the 2K bobbins (4K measured at d.c.), as they are dsigned to optimise the magnetic field. With a 3.3k resistor, you will drop approximately half your ringing voltage across the resistor (measured across resistor and bell-motor, and NOT including capacitor), which is wasteful, even though a meagneto bell will work down to about 8 or 9 mA. __________________ Regds, Russell W. B. G4YLI.

27th Jun 2011, 2:54 pm	#5
StephenMG Retired Dormant Member Join Date: Jul 2010 Location: South Wales, UK. Posts: 15	Re: 3.3k resistor or 4k coils? I'm confident the gongs are fine - I've spent ages (to the point of obsession!) tinkering with them to get them as good as I can. I still feel as though the ring could be stronger though as it is sometimes slightly hesitant. I'm the only one in the house who notices it and everyone else thinks I've some kind of OCD where this is concerned! I'm certainly going to give the 2k coils a go. As you say it's easy and quick to do and there's nowt to lose! Thanks again, Mark