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

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Components and Circuits

Notices

Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

Closed Thread
 
Thread Tools
Old 6th Apr 2020, 9:22 am   #1
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
Default Info regarding reaction controls.

I am attempting to re assemble this cap/resistor reaction control , can anyone tell me which way would it be ie max resistance at min capacitance or max capacitance? Thank's Mick.
vinrads is offline  
Old 6th Apr 2020, 12:42 pm   #2
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
Default Re: Info regarding reaction controls.

I presume this is the Ultra Tiger and I cannot find a circuit that shows a combined variable capacitor/resistor reaction control. If the variable resistor is a low value wirewound it is probably in the cathode resistor for V2 giving maximum gain when set to the lowest value, the capacitor could do either depending on the circuit.
PJL is offline  
Old 6th Apr 2020, 12:53 pm   #3
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Info regarding reaction controls.

I think this query relates to this thread:-

https://www.vintage-radio.net/forum/...d.php?t=165377
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is offline  
Old 6th Apr 2020, 1:24 pm   #4
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
Default Re: Info regarding reaction controls.

Ah Sorry I should have said the set is a Pye 808 battery set ,the resistor is in the heater of the first valve ,acting as a gain control , Mick.
vinrads is offline  
Old 6th Apr 2020, 1:41 pm   #5
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
Default Re: Info regarding reaction controls.

And the capacitor controls the amount of reaction, more capacitance = more reaction.
PJL is offline  
Old 6th Apr 2020, 5:47 pm   #6
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
Default Re: Info regarding reaction controls.

So would you need full heater volts for more reaction, or less heater volts?

I have it working. It is still noisy on the capacitor side, I went for full heaters at lowest capacitance.

Mick.
vinrads is offline  
Old 7th Apr 2020, 7:48 am   #7
crackle
Rest in Peace
 
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
Default Re: Info regarding reaction controls.

I am not an expert but I would expect more reactance to occur with more capacitance as it is a type of positive feedback.
Lowering the capacitance would lower the volume. Likewise lowering the heater volts would also lower the efficiency of the valve having a similar effect. So I would assume lower resistance goes with lower reactance.
But I may be wrong.

I wonder why this thread was not moved to the original thread in the radio section.

Mike
crackle is offline  
Old 7th Apr 2020, 8:52 am   #8
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
Default Re: Info regarding reaction controls.

Hi Mike I started a new thread in the radio section, to see if I could get some interest ,then it was moved here , I have no problem with that , are you saying higher capacitance goes with lower resistance ,that's my thinking .
I am getting used to assembling the unit now I must have done it six times at least , still having problems with int short circuit ,thinking about making some different insulating disks , Mick.

Last edited by vinrads; 7th Apr 2020 at 8:59 am.
vinrads is offline  
Old 7th Apr 2020, 12:17 pm   #9
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,527
Default Re: Info regarding reaction controls.

Quote:
Originally Posted by crackle View Post
I am not an expert but I would expect more reactance to occur with more capacitance as it is a type of positive feedback.
Lowering the capacitance would lower the volume. Likewise lowering the heater volts would also lower the efficiency of the valve having a similar effect. So I would assume lower resistance goes with lower reactance.
But I may be wrong.

I wonder why this thread was not moved to the original thread in the radio section.

Mike
That sounds backwards- a lower resistance in the heater circuit will give more emission and presumably more gain.

Which way round the C-R interact would depend on whether the effects were required to be additive or subtractive. Given the endless historic discussions about the difficulties with achieving smooth reaction control, it may be that making the resistor greater (less gain) as the capacitor value increased (more positive feedback) was useful to tame things.
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline  
Old 7th Apr 2020, 3:08 pm   #10
vinrads
Dekatron
 
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
Default Re: Info regarding reaction controls.

That's rely confused thing now ! Having tried making new insulators which worked,for a while ,I think I need to locate a replacement . Mick.
vinrads is offline  
Old 7th Apr 2020, 5:12 pm   #11
crackle
Rest in Peace
 
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
Default Re: Info regarding reaction controls.

Quote:
Originally Posted by Herald1360 View Post
Quote:
Originally Posted by crackle View Post
I am not an expert but I would expect more reactance to occur with more capacitance as it is a type of positive feedback.
Lowering the capacitance would lower the volume. Likewise lowering the heater volts would also lower the efficiency of the valve having a similar effect. So I would assume lower resistance goes with lower reactance.
But I may be wrong.

I wonder why this thread was not moved to the original thread in the radio section.

Mike
That sounds backwards- a lower resistance in the heater circuit will give more emission and presumably more gain.

Which way round the C-R interact would depend on whether the effects were required to be additive or subtractive. Given the endless historic discussions about the difficulties with achieving smooth reaction control, it may be that making the resistor greater (less gain) as the capacitor value increased (more positive feedback) was useful to tame things.
Chris, you are so right, what a silly mistake. For some reason I was thinking lower volts on heater and wrote about lower resistance.
thanks for correcting it.
Mike
crackle is offline  
Old 7th Apr 2020, 5:19 pm   #12
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
Default Re: Info regarding reaction controls.

If the picture in the linked thread is taken literally, reaction and volume both increase clockwise, so turning clockwise should increase capacitance and reduce resistance.
PJL is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 2:04 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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.