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 > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Reply
 
Thread Tools
Old 27th Jun 2020, 9:26 pm   #41
g4wim_tim
Pentode
 
Join Date: Nov 2018
Location: Freckleton, Lancashire, UK.
Posts: 111
Default Re: Yes, yet another home made valve tester.

Interesting design for a valve tester in the latest issue of Signal from VMARS.

Page 17, Uses an AC signal and relies on the 180 degree phase shift through the valve to measure gm directly.
__________________
Building and tinkering for over 50 years, from 807's to digital amateur TV.
g4wim_tim is offline   Reply With Quote
Old 27th Jun 2020, 9:36 pm   #42
AdrianH
Pentode
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 198
Default Re: Yes, yet another home made valve tester.

Hi Tim,
VMARS is one I am not subscribed to.
BVWS and the valve Museum are enough for now. The tester is basically done for me, the main interest was plotting or verifying the grid anode current curves and a bit of a learning exercise.

I managed to verify it against Davids Simpsons test valve, so think it is good enough for what I require it for at this stage.

Cheers

Adrian
__________________
Ask questions and learn, or try to!
AdrianH is offline   Reply With Quote
Old 30th Jun 2020, 9:09 pm   #43
AdrianH
Pentode
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 198
Default Re: Yes, yet another home made valve tester.

Today I managed to get a switch that had three positions so I could do 4, 40 and 80 mA ranges.

So I used David's standard valve again and started to plot going up to 80 mA range, but after 45mA of anode current the valve would break into oscillation again, so a few hours have been spent trying to figure out why.

Then on a whim I removed the 0.047uF caps I had on the Octal pins, so now only the 1nF caps on the Banana sockets and the ferrites on the leads of course. Instant karma, no signs of instability over the full current meter range.

So for reference I did a full run entered the figures in the spreadsheet and provided plots, the valve has been getting a few hours work today, can emissions improve slightly with use?

Now to test some of my valves!

Adrian
Attached Thumbnails
Click image for larger version

Name:	6AU5GTfinal.jpg
Views:	14
Size:	44.0 KB
ID:	209944  
__________________
Ask questions and learn, or try to!
AdrianH is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 12:33 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 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.