UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Amateur and Military Radio

Notices

Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

Closed Thread
 
Thread Tools
Old 10th Feb 2019, 3:28 am   #1
vu2nan-nandu
Tetrode
 
vu2nan-nandu's Avatar
 
Join Date: Jul 2014
Location: Bangalore, India
Posts: 96
Default Drake TR-4C - PTO problem

In the process of troubleshooting a faulty Drake TR-4C, years ago, the root cause was traced to a non-working PTO.

A visual examination of the mint-condition PCB revealed nothing. Component checks with a multimeter also showed nothing amiss.

Then 'Eureka'! A continuity test showed that the PTO coil was isolated from ground.

A closer examination of the PCB, with a magnifying glass, revealed a dry-solder connection at the ground end of the PTO coil.

Just one solder touch-up and the old workhorse was back in business!

Regards,

Nandu.
__________________
http://nandustips.blogspot.com
vu2nan-nandu is offline  
Old 10th Feb 2019, 12:24 pm   #2
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 14,848
Default Re: Drake TR-4C - PTO problem

Excuse me for asking, but what's a PTO coil?

To me PTO denotes Power Take Off as used by tractors.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now  
Old 10th Feb 2019, 12:42 pm   #3
g4aaw pete
Hexode
 
g4aaw pete's Avatar
 
Join Date: Jan 2008
Location: Maidstone, Kent, UK.
Posts: 423
Default Re: Drake TR-4C - PTO problem

Permeability tuned oscillator. AFAIK all the '4' series Drake rigs used this tuning method.
__________________
Regards
Pete
g4aaw pete is offline  
Old 10th Feb 2019, 12:51 pm   #4
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 14,848
Default Re: Drake TR-4C - PTO problem

Thanks Pete.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now  
Old 10th Feb 2019, 1:08 pm   #5
vu2nan-nandu
Tetrode
 
vu2nan-nandu's Avatar
 
Join Date: Jul 2014
Location: Bangalore, India
Posts: 96
Default Re: Drake TR-4C - PTO problem

Hi Graham,

Yes, as Pete says, PTO refers to 'permeability tuned oscillator'. Thanks, Pete!

Permeability tuning is variable-inductance tuning effected by the movement of a ferrite slug in the coil.

Linear tuning is achieved with a variable-pitch coil.

All Drake rigs use a PTO as VFO.

Regards,

Nandu.
__________________
http://nandustips.blogspot.com
vu2nan-nandu is offline  
Old 10th Feb 2019, 1:53 pm   #6
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 14,848
Default Re: Drake TR-4C - PTO problem

Yes. I'm familiar with permeability tuning as it was often used in car radios having mechanical pre-set tuning. I just hadn't heard the term PTO used in this context before.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now  
Old 10th Feb 2019, 2:10 pm   #7
Jon_G4MDC
Heptode
 
Jon_G4MDC's Avatar
 
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 593
Default Re: Drake TR-4C - PTO problem

Thanks for the enlightenment about variable pitch inductor winding to linearise the tuning.
I have some Swan rigs that use these and I always wondered how they got it so good.
I have never taken one apart - maybe I should now
Jon_G4MDC is online now  
Old 10th Feb 2019, 2:26 pm   #8
vu2nan-nandu
Tetrode
 
vu2nan-nandu's Avatar
 
Join Date: Jul 2014
Location: Bangalore, India
Posts: 96
Default Re: Drake TR-4C - PTO problem

Quote:
Originally Posted by Station X View Post
Yes. I'm familiar with permeability tuning as it was often used in car radios having mechanical pre-set tuning. I just hadn't heard the term PTO used in this context before.
Thanks, Graham, for rekindling old memories - I plumb forgot about vintage car radios with permeability tuning!

Regards,

Nandu.
__________________
http://nandustips.blogspot.com
vu2nan-nandu is offline  
Old 10th Feb 2019, 5:00 pm   #9
vu2nan-nandu
Tetrode
 
vu2nan-nandu's Avatar
 
Join Date: Jul 2014
Location: Bangalore, India
Posts: 96
Default Re: Drake TR-4C - PTO problem

Quote:
Originally Posted by Jon_G4MDC View Post
Thanks for the enlightenment about variable pitch inductor winding to linearise the tuning.
I have some Swan rigs that use these and I always wondered how they got it so good.
I have never taken one apart - maybe I should now
Most welcome, Jon.

Real great rigs were the Collins, Drake & Swan!

Regards,

Nandu.
__________________
http://nandustips.blogspot.com
vu2nan-nandu is offline  
Old 10th Feb 2019, 5:13 pm   #10
Radio Wrangler
Dekatron
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 12,196
Default Re: Drake TR-4C - PTO problem

Drake used a permeability tuned oscillator, the Ten Tec Corsair sports one, but the famous user was Collins i a lot of their professional and amateur classics.

In lieu of a gearbox, a screw thread gave lots of reduction.

Artful variation of the spacing of the turns along the former could give a nice linear tuning scale.

Wear of the screw can be a problem

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 11th Feb 2019, 12:13 am   #11
Dave757
Hexode
 
Join Date: Apr 2009
Location: Scratby, Norfolk, UK.
Posts: 370
Default Re: Drake TR-4C - PTO problem

Hi,

I have a Drake SPR-4 receiver with a PTO, Unfortunately there is wear
on the threads, and tuning can be a bit of a lottery!

Kind regards
Dave
Dave757 is online now  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 11:40 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.