Located - source of NOS transistor audio transformers
2 posters
Page 1 of 1
Re: Located - source of NOS transistor audio transformers
Hi Dave,
Thank you for the info. I found that measuring resistance can be a bit misleading when dealing with such low resistances. 50mA constant current also allows some leeway with making connections. but you method was really interesting to read.
I have already designed a simple IF amplifier, just to test these cans out and see what they will do. Then I can make some measurements (B/W, Q, losses, etc). The old PYE Cambridge PMR radio used a 455kHz "all coils" 2nd IF filter. It looked like a Strepsils tin, which was soldered up after alignment. I am thinking more and more that I need to do some real RF SSB work, as I don't have so many years left.
Thank you for the link for the RF-cans. I will have a good look at that, and also do more experiments with the Reinartz autodyne mixer circuit. Since the RF cans are now hard to come by, it may be possible for me to do my own thing witht he technique and make something that is easy to replicate.
But it is an interesting subject. Thank you once more for your input. Really appreciated.
Sorry about the delay responding but I have had a really hectic and full 9 weeks.
BR Harry - EA/SM0VPO
Thank you for the info. I found that measuring resistance can be a bit misleading when dealing with such low resistances. 50mA constant current also allows some leeway with making connections. but you method was really interesting to read.
I have already designed a simple IF amplifier, just to test these cans out and see what they will do. Then I can make some measurements (B/W, Q, losses, etc). The old PYE Cambridge PMR radio used a 455kHz "all coils" 2nd IF filter. It looked like a Strepsils tin, which was soldered up after alignment. I am thinking more and more that I need to do some real RF SSB work, as I don't have so many years left.
Thank you for the link for the RF-cans. I will have a good look at that, and also do more experiments with the Reinartz autodyne mixer circuit. Since the RF cans are now hard to come by, it may be possible for me to do my own thing witht he technique and make something that is easy to replicate.
But it is an interesting subject. Thank you once more for your input. Really appreciated.
Sorry about the delay responding but I have had a really hectic and full 9 weeks.
BR Harry - EA/SM0VPO
_________________
Everything in this world is either bacon, or it isn't bacon
They say that money cannot bring you happiness, but if you have it then you can always buy more bacon
Re: Located - source of NOS transistor audio transformers
I would just measure the resistance, the bottom end (as I call it) ten we have a few turns to the centre tap and then lots of turns to the top end, an internal cap usually around 180pF is under the can which is connected across top and bottom.
Now then, some circuits have the collector going to the centre tap, the supply going to the 'bottom end' the top end is left unused the 'tuned winding' other circuits may have the supply going to the centre tap while the collector is connected to the 'bottom end' as I call it.
The mouser 455Khz 'cans' The White IF can is - from bottom to centre pin is 2.7R, bottom to top is 6.4R while the secondary is 2.2R.... these figures will vary somewhat and gives a clue which end is the 'top' end.
The Red 'Ossy' coil I have, again from bottom end as I refer is 0.2R to the centre tap and from bottom to top is 3.9R, while the secondary is 0.22R, as you probably know these oscillator coils don't have an internal capacitor.
I've never tried passing 50mA through em' I'd be tempted just to measure the resistance because the wire is mighty thin.
I've got a Bonex and Cirkit catalogue with a load of Toko coil data in, if you want me scan some into a pdf file, let me know, they give all the turns, 'Q' and internal capacitors info.
Toko have stopped making coils, Spectrum is your best bet, http://www.spectrumcomms.co.uk/, they make identical Toko RF coils, not sure if they do I.F cans though, look under 'components.'
Dave.
Now then, some circuits have the collector going to the centre tap, the supply going to the 'bottom end' the top end is left unused the 'tuned winding' other circuits may have the supply going to the centre tap while the collector is connected to the 'bottom end' as I call it.
The mouser 455Khz 'cans' The White IF can is - from bottom to centre pin is 2.7R, bottom to top is 6.4R while the secondary is 2.2R.... these figures will vary somewhat and gives a clue which end is the 'top' end.
The Red 'Ossy' coil I have, again from bottom end as I refer is 0.2R to the centre tap and from bottom to top is 3.9R, while the secondary is 0.22R, as you probably know these oscillator coils don't have an internal capacitor.
I've never tried passing 50mA through em' I'd be tempted just to measure the resistance because the wire is mighty thin.
I've got a Bonex and Cirkit catalogue with a load of Toko coil data in, if you want me scan some into a pdf file, let me know, they give all the turns, 'Q' and internal capacitors info.
Toko have stopped making coils, Spectrum is your best bet, http://www.spectrumcomms.co.uk/, they make identical Toko RF coils, not sure if they do I.F cans though, look under 'components.'
Dave.
Codar- Posts : 7
Join date : 2019-02-18
Age : 75
Location : Nr. Manchester
Re: Located - source of NOS transistor audio transformers
Hello Dave,
I also have loads of 455kHz IF cans, but I am lacking data, or to be more accurate, I have conflicting data for the same type of cans.
I would really appreciate the e-mailed document.
I was seriously thinking about passing 50mA through the windings and measuring the voltage drop to find which end was which, then pulsing the current to find the winding directions.
In the batch I bought I received two 10mm "yellow" cans and it seems that they are the same but one has a tuned primary and the other has a tuned secondary.
Perhaps I should build a little AM IF amplifier to test them out? It would be a nice little project for me right now with limited facilities.
But I am still seeking the RED oscillator cans.
Very best regards and thank you for thinking about me.
/Harry - SM0VPO (EA/SM0VPO)
PS
british.inteligence.sweden@sm0vpo.com
or
hotmail@sm0vpo.com
(Do NOT correct them. They are spelled correctly. Both are genuine )
(Spammers don't reply to the first. People don't believe the second)
I also have loads of 455kHz IF cans, but I am lacking data, or to be more accurate, I have conflicting data for the same type of cans.
I would really appreciate the e-mailed document.
I was seriously thinking about passing 50mA through the windings and measuring the voltage drop to find which end was which, then pulsing the current to find the winding directions.
In the batch I bought I received two 10mm "yellow" cans and it seems that they are the same but one has a tuned primary and the other has a tuned secondary.
Perhaps I should build a little AM IF amplifier to test them out? It would be a nice little project for me right now with limited facilities.
But I am still seeking the RED oscillator cans.
Very best regards and thank you for thinking about me.
/Harry - SM0VPO (EA/SM0VPO)
PS
british.inteligence.sweden@sm0vpo.com
or
hotmail@sm0vpo.com
(Do NOT correct them. They are spelled correctly. Both are genuine )
(Spammers don't reply to the first. People don't believe the second)
_________________
Everything in this world is either bacon, or it isn't bacon
They say that money cannot bring you happiness, but if you have it then you can always buy more bacon
Re: Located - source of NOS transistor audio transformers
I got some I.F cans from Mouser... and some Red and Blue audio output /driver transformers. Got the data sheet, I'll Email to you.
Dave
Dave
Codar- Posts : 7
Join date : 2019-02-18
Age : 75
Location : Nr. Manchester
Located - source of NOS transistor audio transformers
Hi you guys,
I am still seeking a source for the RED local oscillator coils used in the old MW transistor radios.
I managed to find the 455kHz IF cans, but yesterday I hit gold-dust
Remember the old two-transformer audio amplifiers? Well I found them in the UK. https://www.cricklewoodelectronics.com
They are a little bit "pricey" but affordable. Based and delivers from the UK, so no "China Tax" like we have in Sweden or the USA.
https://www.cricklewoodelectronics.com/LT44-Miniature-Audio-Driver-Transformer-20K-ohms-to-2-x-1K-ohms.html
This is the blue transformer upon which I based a phased SSB exciter to feed a four-phase RC ladder for the four-phase balanced modulator(s), see http://213.114.131.21/tx/p-ssb.htm. Now you have a source for them.
And the 3Ω output transformer:
https://www.cricklewoodelectronics.com/LT700-Miniature-Audio-Output-Transformer-1000-ohms-to-3.2-ohms-3.2-ohms.html
Very best regards from Harry - SM0VPO
I am still seeking a source for the RED local oscillator coils used in the old MW transistor radios.
I managed to find the 455kHz IF cans, but yesterday I hit gold-dust
Remember the old two-transformer audio amplifiers? Well I found them in the UK. https://www.cricklewoodelectronics.com
They are a little bit "pricey" but affordable. Based and delivers from the UK, so no "China Tax" like we have in Sweden or the USA.
https://www.cricklewoodelectronics.com/LT44-Miniature-Audio-Driver-Transformer-20K-ohms-to-2-x-1K-ohms.html
This is the blue transformer upon which I based a phased SSB exciter to feed a four-phase RC ladder for the four-phase balanced modulator(s), see http://213.114.131.21/tx/p-ssb.htm. Now you have a source for them.
And the 3Ω output transformer:
https://www.cricklewoodelectronics.com/LT700-Miniature-Audio-Output-Transformer-1000-ohms-to-3.2-ohms-3.2-ohms.html
Very best regards from Harry - SM0VPO
_________________
Everything in this world is either bacon, or it isn't bacon
They say that money cannot bring you happiness, but if you have it then you can always buy more bacon
Similar topics
» Tuning capacitors and IF transformers
» LiPo pouch cells
» Designing transformers
» 2n2222 PUSH PUL AMP
» Coils and transformers
» LiPo pouch cells
» Designing transformers
» 2n2222 PUSH PUL AMP
» Coils and transformers
Page 1 of 1
Permissions in this forum:
You can reply to topics in this forum