Use of Pye Ranger transformer for a valve Amp? - UK Vintage Radio Repair and Restoration Discussion Forum

Bazz4CQJ · 15th Mar 2012, 1:45 am

Some people will remember the various Pye radio telephones that were around in the 1960's and widely used by amateurs after conversion to 4 and 2m. One of the earlier Pye Ranger sets used amplitude modulation, the audio coming from a pair of EL90 (6AQ5) couple by a round "potted" transformer which looked much like a bean can. That transformer has two secondary windings, one being a relatively high impedance winding which fed the RF output valve but the other winding is a very low impedance winding and I never knew what it did. The 2 possibilities I think are that it either provided feedback for audio compression or the other possibility is that it could be used to feed a public address system.

I have three of these transformers and I am intrigued by the idea that if that winding would drive a speaker of the right impedance, these components could form the basis of an interesting audio amp project. Has anyone any knowledge of these items?

G8HQP Dave · 15th Mar 2012, 11:54 am

It would probably have restricted frequency response, so not hi-fi!

Bazz4CQJ · 15th Mar 2012, 1:21 pm

Hi Dave; it is certainly correct that those rigs restricted the audio to a range of about 200-3000Hz, using filters in the pre-amp. In the absence of original technical info, I am wondering what fairly simple tests could be done to find out the key parameters. Could the frequency response be assessed by using a signal generator to drive one winding between 20Hz to 20kHz and observing the output on a secondary? If that proved to good, it's the tests needed to verify the impedance and the power rating of the "second" secondary that I'm not sure about

G8HQP Dave · 15th Mar 2012, 1:44 pm

As a start you could measure the resistance and inductance of each winding, with other windings open circuit. Then measure the inductance of the primary with the secondaries shorted.

TrevorG3VLF · 15th Mar 2012, 7:45 pm

Bazz

I have been asked to look at a ws62 set (Pye) and get it going on receive. It has a rotary convertor which is noisy. Later versions had an invertor and it may be advatageous to update it. Do you have a spare Pye invertor transformer?
Thanks

Trevor

Bazz4CQJ · 16th Mar 2012, 10:15 pm

Trevor; sorry cannot help there; my OCD only extended to collecting mod transformers! If you can, try find something from a Pye Vanguard, a later model with an inverter giving 400V at ~100mA for the Tx and ~200V for the Rx.

Dave, I can get the resistance and inductance values; does the shorting action give an indication of the power rating on the secondary as a refection of its loading effect?

Bazz

16th Mar 2012, 11:20 pm

Shorting the other winding gives a measure of the leakage inductance, i.e. how bad it is. With an ideal transformer shorting one winding (givinig it zero henrys) would reflect zero henries into the other one, with good transfomers this is thounsands to one, for example my output transformers have a primary inductance of 300H but shorting the output they are 40mH.

G8HQP Dave · 17th Mar 2012, 12:05 am

Total power rating may have to be guessed from size and weight, with the advantage that we know what the conditions were for modulator use. The extra secondary which you are interested in can be investigated by considering the ratios of inductances and resistances.

If two windings are meant to handle similar power then they will occupy similar amounts of space. The inductance ratio is a rough guide to impedance ratio, as both vary like turns squared. If the resistance ratio differs markedly from this, then the windings are not meant to handle similar power. This is not highly accurate, but should let you distinguish between a feedback winding and an alternative output winding.

techiesteve · 17th Mar 2012, 7:08 am

Trevor, have you seen this article http://www.royalsignals.org.uk/artic...2-inverter.htm. I've never come across the source of the transformer core in the article, but RS sell it too.

Quote:

Originally Posted by TrevorG3VLF

Bazz

I have been asked to look at a ws62 set (Pye) and get it going on receive. It has a rotary convertor which is noisy. Later versions had an invertor and it may be advatageous to update it. Do you have a spare Pye invertor transformer?
Thanks

Trevor

TrevorG3VLF · 17th Mar 2012, 4:16 pm

Thanks, I had not seen the article. Will have to see if the owner wants the set 'improved'

15th Mar 2012, 1:45 am	#1
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Use of Pye Ranger transformer for a valve Amp? Some people will remember the various Pye radio telephones that were around in the 1960's and widely used by amateurs after conversion to 4 and 2m. One of the earlier Pye Ranger sets used amplitude modulation, the audio coming from a pair of EL90 (6AQ5) couple by a round "potted" transformer which looked much like a bean can. That transformer has two secondary windings, one being a relatively high impedance winding which fed the RF output valve but the other winding is a very low impedance winding and I never knew what it did. The 2 possibilities I think are that it either provided feedback for audio compression or the other possibility is that it could be used to feed a public address system. I have three of these transformers and I am intrigued by the idea that if that winding would drive a speaker of the right impedance, these components could form the basis of an interesting audio amp project. Has anyone any knowledge of these items?

15th Mar 2012, 11:54 am	#2
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Use of Pye Ranger transformer for a valve Amp? It would probably have restricted frequency response, so not hi-fi!

15th Mar 2012, 1:21 pm	#3
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Use of Pye Ranger transformer for a valve Amp? Hi Dave; it is certainly correct that those rigs restricted the audio to a range of about 200-3000Hz, using filters in the pre-amp. In the absence of original technical info, I am wondering what fairly simple tests could be done to find out the key parameters. Could the frequency response be assessed by using a signal generator to drive one winding between 20Hz to 20kHz and observing the output on a secondary? If that proved to good, it's the tests needed to verify the impedance and the power rating of the "second" secondary that I'm not sure about

15th Mar 2012, 1:44 pm	#4
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Use of Pye Ranger transformer for a valve Amp? As a start you could measure the resistance and inductance of each winding, with other windings open circuit. Then measure the inductance of the primary with the secondaries shorted.

15th Mar 2012, 7:45 pm	#5
TrevorG3VLF Rest in Peace Join Date: Apr 2011 Location: Matlock, Derbyshire, UK. Posts: 1,378	Re: Use of Pye Ranger transformer for a valve Amp? Bazz I have been asked to look at a ws62 set (Pye) and get it going on receive. It has a rotary convertor which is noisy. Later versions had an invertor and it may be advatageous to update it. Do you have a spare Pye invertor transformer? Thanks Trevor

16th Mar 2012, 10:15 pm	#6
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Use of Pye Ranger transformer for a valve Amp? Trevor; sorry cannot help there; my OCD only extended to collecting mod transformers! If you can, try find something from a Pye Vanguard, a later model with an inverter giving 400V at ~100mA for the Tx and ~200V for the Rx. Dave, I can get the resistance and inductance values; does the shorting action give an indication of the power rating on the secondary as a refection of its loading effect? Bazz

16th Mar 2012, 11:20 pm	#7
Guest Guest Posts: n/a	Re: Use of Pye Ranger transformer for a valve Amp? Shorting the other winding gives a measure of the leakage inductance, i.e. how bad it is. With an ideal transformer shorting one winding (givinig it zero henrys) would reflect zero henries into the other one, with good transfomers this is thounsands to one, for example my output transformers have a primary inductance of 300H but shorting the output they are 40mH.

17th Mar 2012, 12:05 am	#8
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Use of Pye Ranger transformer for a valve Amp? Total power rating may have to be guessed from size and weight, with the advantage that we know what the conditions were for modulator use. The extra secondary which you are interested in can be investigated by considering the ratios of inductances and resistances. If two windings are meant to handle similar power then they will occupy similar amounts of space. The inductance ratio is a rough guide to impedance ratio, as both vary like turns squared. If the resistance ratio differs markedly from this, then the windings are not meant to handle similar power. This is not highly accurate, but should let you distinguish between a feedback winding and an alternative output winding.

17th Mar 2012, 4:16 pm	#10
TrevorG3VLF Rest in Peace Join Date: Apr 2011 Location: Matlock, Derbyshire, UK. Posts: 1,378	Re: Use of Pye Ranger transformer for a valve Amp? Thanks, I had not seen the article. Will have to see if the owner wants the set 'improved'