Portadyne Model Number - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Radio Tech · 27th Mar 2017, 1:40 pm

Hello Graham

I made the sections starting from the top 136 180 and 730 Ohms, but the odd thing is now that I have changed the 1D5 rectifier the HT is as it should be and the heater in this is glowing as it should. Now I have to try and work out how to trace an RF signal but as I haven't got a proper circuit diagram for it and no information on the TX21 which is I think being used as the frequency changer (triode hexode) I will try and work out if there is anything coming from this valve.

Ken

Station X · 27th Mar 2017, 1:45 pm

I would suggest that the 1D5's heater is still being under run. What is the voltage across it now? Come to that what are the voltages across the other heaters and across the dropper?

As I've said, "Things just don't add up here".

ms660 · 27th Mar 2017, 4:21 pm

Quote:

Originally Posted by Radio Tech

I made the sections starting from the top 136 180 and 730 Ohms, but the odd thing is now that I have changed the 1D5 rectifier the HT is as it should be and the heater in this is glowing as it should. Now I have to try and work out how to trace an RF signal but as I haven't got a proper circuit diagram for it and no information on the TX21 which is I think being used as the frequency changer (triode hexode) I will try and work out if there is anything coming from this valve.

TX21 pinout:

http://www.vintageradio.nl/buizen/TX21.htm

Lawrence.

Station X · 27th Mar 2017, 4:32 pm

Wouldn't it be better to get the audio stages working first?

ms660 · 27th Mar 2017, 4:37 pm

I would have thought so, like you I'm still perplexed by some of the measurements etc that's been posted so far.

Lawrence.

Radio Tech · 28th Mar 2017, 8:40 am

Thanks Lawrence for pin out of TX21 valve, and Graham, the audio stage does work and yes it does seem very odd that things do not add up. I have tried feeding an RF signal in but not knowing the IF frequency I just swept and a tone came out of LS at around 398kc, I would have thought the IF would have been around 130kc. After around five mins all the valves are pretty warm which suggests heaters ok but not checked the actual voltage across each valve which will be worth doing.

Ken

Radio Tech · 28th Mar 2017, 2:42 pm

Hi fellow members

Yes you were quite right Graham in suspecting the heaters being under run, the TX21 was certainly that, 0.3V! and the rectifier was under run by 20V, I had a look at the dropper and as Lawrence suggested around 480 Ohms he estimated, I adjusted the banjo clips I have got the TX21 sitting at 17V and the rectifier at 32V so a little more adjustment and I should see all the valves with their correct heater volts and after that the set should come back to life once again.

will keep you all posted.

Ken

Radio Tech · 29th Mar 2017, 9:23 am

Hi Folks

Have adjusted dropper resistance and got these voltages on the heaters 1D5 35V PP5 30V VP13C 11.7V T21 18V DDT13 11.7. And the overall resistance of the dropper 675 Ohms (that is the section actually being used). Now got to find some way of tuning the set for better signals on MW I have managed to get the set to receive radio 5 live.

Ken

Radio Tech · 30th Mar 2017, 8:50 am

An update on this set,

I have managed to retune the set, what I did was to look up some BBC radio station frequencies and then tune a sig gen to those then set the tuning pointer on the dial to that of the station and adjust the padder caps underneath so that everything lined up.

Just got to find a set of knobs, do the back panel and sit back and admire the work.

Ken

Radio Tech · 31st Mar 2017, 8:51 pm

Well fellow members, the set is working now and all complete so here are two or three pictures so you can see the final look of the set in comparison to what it looked like, I even made another back panel from some five ply I had.

Best wishes

Ken

Kentode · 1st Apr 2017, 5:21 am

Congratulations Ken, I've been following this post and I've been very impressed with the deductive powers used by everyone, yourself included.

Did the wire of the dropper require any coating removed as Graham suggested?

I look forward to seeing your next restoration.

Radio Tech · 1st Apr 2017, 2:20 pm

Hello Ken

No, wire on dropper seemed ok without removing any coating,

Will not be too long before my next project comes along.

Have sent you a pm

Best wishes

Ken

27th Mar 2017, 1:40 pm	#41
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number Hello Graham I made the sections starting from the top 136 180 and 730 Ohms, but the odd thing is now that I have changed the 1D5 rectifier the HT is as it should be and the heater in this is glowing as it should. Now I have to try and work out how to trace an RF signal but as I haven't got a proper circuit diagram for it and no information on the TX21 which is I think being used as the frequency changer (triode hexode) I will try and work out if there is anything coming from this valve. Ken

27th Mar 2017, 1:45 pm	#42
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Portadyne Model Number I would suggest that the 1D5's heater is still being under run. What is the voltage across it now? Come to that what are the voltages across the other heaters and across the dropper? As I've said, "Things just don't add up here". __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

27th Mar 2017, 4:32 pm	#44
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Portadyne Model Number Wouldn't it be better to get the audio stages working first? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

27th Mar 2017, 4:37 pm	#45
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Portadyne Model Number I would have thought so, like you I'm still perplexed by some of the measurements etc that's been posted so far. Lawrence.

28th Mar 2017, 8:40 am	#46
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number Thanks Lawrence for pin out of TX21 valve, and Graham, the audio stage does work and yes it does seem very odd that things do not add up. I have tried feeding an RF signal in but not knowing the IF frequency I just swept and a tone came out of LS at around 398kc, I would have thought the IF would have been around 130kc. After around five mins all the valves are pretty warm which suggests heaters ok but not checked the actual voltage across each valve which will be worth doing. Ken

28th Mar 2017, 2:42 pm	#47
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number Hi fellow members Yes you were quite right Graham in suspecting the heaters being under run, the TX21 was certainly that, 0.3V! and the rectifier was under run by 20V, I had a look at the dropper and as Lawrence suggested around 480 Ohms he estimated, I adjusted the banjo clips I have got the TX21 sitting at 17V and the rectifier at 32V so a little more adjustment and I should see all the valves with their correct heater volts and after that the set should come back to life once again. will keep you all posted. Ken

29th Mar 2017, 9:23 am	#48
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number Hi Folks Have adjusted dropper resistance and got these voltages on the heaters 1D5 35V PP5 30V VP13C 11.7V T21 18V DDT13 11.7. And the overall resistance of the dropper 675 Ohms (that is the section actually being used). Now got to find some way of tuning the set for better signals on MW I have managed to get the set to receive radio 5 live. Ken

30th Mar 2017, 8:50 am	#49
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number An update on this set, I have managed to retune the set, what I did was to look up some BBC radio station frequencies and then tune a sig gen to those then set the tuning pointer on the dial to that of the station and adjust the padder caps underneath so that everything lined up. Just got to find a set of knobs, do the back panel and sit back and admire the work. Ken

31st Mar 2017, 8:51 pm	#50
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number Well fellow members, the set is working now and all complete so here are two or three pictures so you can see the final look of the set in comparison to what it looked like, I even made another back panel from some five ply I had. Best wishes Ken Attached Thumbnails

1st Apr 2017, 5:21 am	#51
Kentode Octode Join Date: Mar 2015 Location: Yorkshire, England. Posts: 1,301	Re: Portadyne Model Number Congratulations Ken, I've been following this post and I've been very impressed with the deductive powers used by everyone, yourself included. Did the wire of the dropper require any coating removed as Graham suggested? I look forward to seeing your next restoration. __________________ Regards, Ken. BVWS member

1st Apr 2017, 2:20 pm	#52
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Re: Portadyne Model Number Hello Ken No, wire on dropper seemed ok without removing any coating, Will not be too long before my next project comes along. Have sent you a pm Best wishes Ken