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 Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Reply
 
Thread Tools
Old 5th Sep 2019, 2:39 pm   #1
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Taylor 45C Grid Volt Calibration

Yet another post on the Taylor 45C but I have scoured everywhere for information

My Taylor 45C seems to work well but I cannot be sure of the grid volt calibration which is of fundamental importance to obtaining accurate mutual conductance readings.

So I kindly ask other owners of this instrument to connect their 'scope to the G1 and K sockets of a valve holder and post a reply. It will be very useful to see if my 45C is similar to others.

This is what I get with grid volts set to 10V (and I've also got results for 1V, 5V and 15V).

Click image for larger version

Name:	Grid Volt Trace set at 10V.jpg
Views:	63
Size:	93.5 KB
ID:	189538

All the relevant resistors and power supply in my 45C are to Taylor specification.
DoubleWound is offline   Reply With Quote
Old 5th Sep 2019, 6:31 pm   #2
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 8,164
Default Re: Taylor 45C Grid Volt Calibration

What are the peak to peak results for the 1V, 5V and 15V settings?

Lawrence.
ms660 is offline   Reply With Quote
Old 5th Sep 2019, 8:23 pm   #3
sven_swe
Tetrode
 
Join Date: May 2018
Location: Cologne, Germany
Posts: 72
Default Re: Taylor 45C Grid Volt Calibration

Very nice Initiative, I have two Taylor 45C's. Unfortunately I don't have a fancy scope like you, only my old Tektronix from the 70's. Let's see if I can come up with something.
Would be interesting if you posted all values, like mentioned in previous post
sven_swe is offline   Reply With Quote
Old 5th Sep 2019, 8:26 pm   #4
Megatron
Tetrode
 
Join Date: Mar 2019
Location: Monmouth, Monmouthshire, Wales, UK.
Posts: 51
Default Re: Taylor 45C Grid Volt Calibration

I sort of shelved mine, couldnt get sensible readings and ran out of things to check.
scope readings on the sockets would be really useful.
Megatron is offline   Reply With Quote
Old 6th Sep 2019, 1:41 am   #5
sven_swe
Tetrode
 
Join Date: May 2018
Location: Cologne, Germany
Posts: 72
Default Re: Taylor 45C Grid Volt Calibration

Here's my result. Long time since I used the scope..

I have a little bit lower values than you it seems. Stock values on components. Taylor #2 has silicone diodes instead of the selenium rectifier. But they are very much alike in the results.
Attached Thumbnails
Click image for larger version

Name:	taylor45c_grid_voltage.png
Views:	37
Size:	8.7 KB
ID:	189589  
sven_swe is offline   Reply With Quote
Old 6th Sep 2019, 6:58 am   #6
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Re: Taylor 45C Grid Volt Calibration

I am grateful for the feedback folks.

In answer to the question from ms660 the "peak to peak" figures on other settings are below and I have deducted the small +ve value:-

Dial Setting / Scope Peak Reading
1V / 1.5V
5V / 6.0V
10V / 12.0V
15V / 17.0V

I have checked that the knob position at 0V is correct and that the meter is accurate (not that the meter is involved in this analysis).

My conclusion is that this is how the instrument left the factory but I would still appreciate as much feedback as possible from users of good unmolested 45Cs using a 'scope to determine voltages.

Last edited by DoubleWound; 6th Sep 2019 at 7:12 am.
DoubleWound is offline   Reply With Quote
Old 6th Sep 2019, 11:46 am   #7
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 8,164
Default Re: Taylor 45C Grid Volt Calibration

I did a quick calc based on the transformers output voltage shown in the schematic using a "perfect diode" I calculated 1.178 volts per grid volts setting, ie: 17.67v p to p for the 15 volts setting, 11.78v p to p for the 10 volts setting etc.

So throw the diodes forward voltage drop (whatever that may be) into the mix and the waveform you displayed isn't that far out taking normal component tolerances and mains voltage variations into consideration.

Lawrence.
ms660 is offline   Reply With Quote
Old 6th Sep 2019, 12:21 pm   #8
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Re: Taylor 45C Grid Volt Calibration

Lawrence, that is really helpful information and is starting to put my mind at rest.

I will take some accurate measurements of the actual transformer VAC output and the half wave rectified voltage disconnected from the rest of the instrument circuit. I'll continue to use a 'scope since my Avo 8 or DMM may not give the true picture for a half wave rectified voltage.

I'm actually surprised that Taylor seems to have failed in publishing the data I seek. Maybe some member here has Taylor 45C Service Sheets if they ever existed.
DoubleWound is offline   Reply With Quote
Old 6th Sep 2019, 2:52 pm   #9
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Re: Taylor 45C Grid Volt Calibration

Just an update to say that:

The "disconnected" output of the transformer is 20.9Vrms.

The "disconnected" half wave output is 28.4Vpp.

Temporarily substituting the original Taylor diode with a UF4007 the "disconnected" half wave output rose to 30.4Vpp.

I still hope to receive some more 'scope readings connected to G1 & K from other owners but for the time being I'll assume my 45C is OK.
DoubleWound is offline   Reply With Quote
Old 6th Sep 2019, 9:52 pm   #10
sven_swe
Tetrode
 
Join Date: May 2018
Location: Cologne, Germany
Posts: 72
Default Re: Taylor 45C Grid Volt Calibration

I just tested again with another scope, now more in line with yours. Good to see, seems like it's more in order. A little high though.

Grid Voltage Setting Gid voltage OSC Vpp
2 2.5V
5 6V
10 12.4V
15 18V
sven_swe is offline   Reply With Quote
Old 6th Sep 2019, 10:14 pm   #11
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Re: Taylor 45C Grid Volt Calibration

Sven, this is really good feedback - thanks.

If more 45C owners came back with their results we may be able to ascertain what Taylor should have published in the first place.
DoubleWound is offline   Reply With Quote
Old 6th Sep 2019, 10:26 pm   #12
sven_swe
Tetrode
 
Join Date: May 2018
Location: Cologne, Germany
Posts: 72
Default Re: Taylor 45C Grid Volt Calibration

We could also create some "standardized tubes" to pass around, like they did here for the AVO testers if that would be of interest. I surely would like to compare mine with others, its a great little tester the Taylor 45C.
sven_swe is offline   Reply With Quote
Old 10th Sep 2019, 11:13 am   #13
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Re: Taylor 45C Grid Volt Calibration

Quote:
Originally Posted by sven_swe View Post
We could also create some "standardized tubes" to pass around, like they did here for the AVO testers if that would be of interest. I surely would like to compare mine with others, its a great little tester the Taylor 45C.
That would be very interesting to carry out.

Although my resistors are within Taylor tolerances I'm going to replace them with spot on values when I get back from holiday later this month. If there's any change in grid voltages I'll post again.

I don't expect much change but the old resistors are bound to creep up in value as time goes on.
DoubleWound is offline   Reply With Quote
Old 10th Sep 2019, 4:34 pm   #14
Freya
Octode
 
Freya's Avatar
 
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,581
Default Re: Taylor 45C Grid Volt Calibration

45C #1

Grid Voltage Setting Grid voltage OSC Vpp
2 2.2V
5 6V
10 11.1V
15 14V

45C #2

Grid Voltage Setting Grid voltage OSC Vpp
2 2V
5 5.5V
10 10.3V
15 15.8V

Taylor 47

Grid Voltage Setting Grid voltage OSC Vpp
2 3.5V
5 7V
10 12.4V
15 16.7V

Taylor 45

Grid Voltage Setting Grid voltage OSC Vpp
2 2.8V
5 6.6V
10 11.6V
15 15.5V

My other 45c is out on loan, and the other two 47`s have bad transformers
__________________
Stephen
________________________

"It`s only an old telly"
Freya is offline   Reply With Quote
Old 20th Sep 2019, 4:28 pm   #15
DoubleWound
Triode
 
Join Date: Sep 2018
Location: East Grinstead, West Sussex, UK.
Posts: 26
Default Re: Taylor 45C Grid Volt Calibration

Quote:
Originally Posted by Freya View Post
45C #1

Grid Voltage Setting Grid voltage OSC Vpp
2 2.2V
5 6V
10 11.1V
15 14V

45C #2

Grid Voltage Setting Grid voltage OSC Vpp
2 2V
5 5.5V
10 10.3V
15 15.8V

Taylor 47

Grid Voltage Setting Grid voltage OSC Vpp
2 3.5V
5 7V
10 12.4V
15 16.7V

Taylor 45

Grid Voltage Setting Grid voltage OSC Vpp
2 2.8V
5 6.6V
10 11.6V
15 15.5V

My other 45c is out on loan, and the other two 47`s have bad transformers
Very helpful information - thanks very much.

I'm just back from holiday today and I'll post my figures again after I've changed some more resistors to exact Taylor values.
DoubleWound is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 9:33 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.