Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jul Wed 17, 2019 9:16 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 15 posts ] 
Author Message
 Post subject: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 5:07 am 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
Hello

Anyone have the settings for a 25Z4 tube. I have an Eico 666 and a knight 520. I believe the 600 series settings will work as well. Nothing on the roll charts or Bama site. Thanks!

Rod


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 6:26 am 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 37331
Location: Livermore, CA
Rod

Use 35Z4 and reduce filament voltage from 35 to 25 volts.

_________________
Norm


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 6:44 pm 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
How stupid am I! Thanks Norm.


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 6:49 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13826
What do you have that uses a 25Z4??? on the grille cloth site there are only three sets listed and without doubt, two of those are incorrect...


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 7:22 pm 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
35Z5 wrote:
What do you have that uses a 25Z4??? on the grille cloth site there are only three sets listed and without doubt, two of those are incorrect...


Here is the radio.

http://www.radiomuseum.org/r/portadyne_portadyne_table_model_2.html

I can't find a schematic for it anywhere and can't even confirm it's model designation but mine looks identical to the one pictured. I picked it and another French one up that I can't identify.

Rod


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 7:29 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 37331
Location: Livermore, CA
Rod

Use settings for 35Z4 except for filament, as mentioned, to test the 25Z4. Do not attempt to use a 35Z4 in your radio as it has different filament current. Tube filaments are wired in series in your radio. All tubes must have the same current rating when used in this radio.

For information on your radio might try Paul Stenning's UK forum:

http://www.vintage-radio.net/forum/index.php

_________________
Norm


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 8:35 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13826
Interesting...

Note the radio pictured on the RM site may be using a full wave rectifier, at least it appears to have two plate structures...



Tom


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 8:41 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 37331
Location: Livermore, CA
Tom

Wonder if it's a 25Z6? That tube was commonly used with the others..

_________________
Norm


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 9:19 pm 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
The tube marking is gone on one and all I can make out is 25 and 6. I'm assuming it's the 25a6 which failed on that setting on my Eico. Has a good rattle inside it as well. I'm using the tube lineup in the radio in radiomuseum as the others look to be correct. The two 6k8's have 6a8's in place but my understanding is that they are interchangeable. The 6q7 is in place as well as the 25z4. I used the 35z4 settings with 25 v filiment selected which showed a short as soon as I plugged it in the socket. I'll grab a few tubes and go from there. Thanks for the help!

Rod


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Mon 16, 2017 10:07 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13826
Norm Leal wrote:
Tom

Wonder if it's a 25Z6? That tube was commonly used with the others..


Yes I was thinking same... Would be easy enough to use the Z6, as long as the are no connections on the socket to pins 3&4 would be a direct swap... Or it's easy enough to clip those pins and make it electrically same as a 25Z4...


Tom


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Tue 17, 2017 8:12 pm 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
Sure wish I had a schematic for this thing! In looking at the connections, pin 1 is unused. Pin 2 and 3 have one side of the line cord attached. Pin 4 goes to filter cap and is also bridged to pin 8. Pin 5 and 6 are unused and 7 goes to pin 2 of the 25A6. Should I be able to drop a 25z6 in this?


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Tue 17, 2017 8:31 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 37331
Location: Livermore, CA
As long as pin #5 is unused you can use a 25Z6 tube. Pin #5 is the second plate. For more available current best if it was connected to pin #3.

_________________
Norm


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Tue 17, 2017 9:08 pm 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
Thanks for that. Looks like I have another issue. I didn't catch on to this right away but have a look at this coil.

https://goo.gl/photos/yYi5cvB9q6hmRj7m6

Salvageable? What could be possible causes?

Rod


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Tue 17, 2017 9:40 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 37331
Location: Livermore, CA
Rod

This is most likely the antenna coil? If so lightening might have caused wire to burn and unwind? If that is a non tuned section of the coil you could rewind the bad part. Exact number of turns is critical unless it's tuned.

AES, http://www.tubesandmore.com and Radio Daze, http://www.radiodaze.com both sell universal antenna coils. Problem being coil is only for broadcast band, not short wave.

PTOP may have a replacement but the list is long.

http://www.oldradioparts.com/2a6fla.txt

_________________
Norm


Top
 Profile  
 
 Post subject: Re: 25Z4 tube settings for Eico or Knight testers
PostPosted: Jan Tue 17, 2017 9:46 pm 
Member

Joined: Sep Sat 10, 2016 10:30 pm
Posts: 230
Location: Didsbury Alberta Canada
Great, thank you very much. I'll see what happens with replacement tubes and go from there.

Rod


Top
 Profile  
 
Post New Topic Post Reply  [ 15 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB