Luftwaffe NA8 utility power supply for 100 Watt Sender

[kriegsfunker]

When I put the multimeter on the wires, it shows open line, no matter how i do it.

[val]

Maybe the picture is deceptive but i see the thin wires come out from resistor porcelain itself.

I have seen two types of similar resistors:

- flexible wires come out from resistor and they are connected to clamp, which just holding the resistor

- flat rigid lead come out from resistor, they are connected to clamps which just holding the resistor

This is in case of fixed value resistor. Adjustable use clamp, then the resistor wire is visible and clamp

is pressed against the wire.

You should remove the resistor from capacitor, remove the clamps and give the wire a good cleaning.

I see a lot of corrosion there.

[tornfuté]

the sister of Na8 the SGLT  like the na8 you can also lower the anode voltage  to 800 v and use it with a 80 WS it miss also the  front glimmlampe

 but i have somewhere a second  set and i believe it's present

 

[kriegsfunker]

Interesting device.   Thank you for sharing.  Does it have a giant capacitor with a bleed resistor on the 1000V output?

[val]

Thanks @tornfuté, now i know how T100 looks like.

BTW, the biggest selenium rectifier i have seen so far is inside the Gleichrichter.a

[kriegsfunker]

These selenium rectifiers go bad.   I don't know how, but they do.

[kriegsfunker]

Yes, there are thin twisted wires that come from both sides of the resistor.   The whole thing looks good, and I have cleaned the wires.   I will take a steel brush to the wires and see if that works.   BTW, the clamps were corroded, but I cleaned them.   That still didn't make the resistor work.

[val]

3 minutes ago, kriegsfunker said:

These selenium rectifiers go bad.   I don't know how, but they do.

Yes, they disintegrate with time and catch even fire, so with them should be careful...

http://w3hwj.com/index_files/RBSelenium2.pdf

[kriegsfunker]

What is the advice here - replace them (hide the small ones somewhere below)?  Or continue to use?

[val]

14 minutes ago, kriegsfunker said:

What is the advice here - replace them (hide the small ones somewhere below)?  Or continue to use?

Radio performance is dictated by the quality of the PSU. So for sake of tube's health and performance i trust

modern rectifies. But when i use selenium rectifies, i will never leave them unattended or run them in hours,

i just have some bad experiences with them. They are risk.

[kriegsfunker]

Thanks Val.

[val]

https://en.wikipedia.org/wiki/Selenium_rectifier

Quote

Selenium rectifiers had a shorter lifespan than desired. During catastrophic failure they produced significant quantities of malodorous and highly toxic fumes

 

[kriegsfunker]

Monster capacitor,  I will have to re-form it.  It has the right capacitance when measured.    Any good ways to reform this one?    Interesting that the capacitor was made in the Czech Republic.

 

 

 

[tornfuté]

hello i open the left side , right side and back of SGLT 100 , design is different from NA8  there is not only a 30 uf capacitor , but  2 of 10 uf , i see no resistance

   like on yuri set . there is a big resistor but for dropping the anode value , one connection is broken , i know somebody who own a NA8  i will asks him if he would be kind to open his set and measure the resistance .

i had never open the SGLT100 and i see that also is missing 2 glimlampe  Inside  see  white sockets . overall it seems me Inside is in good cosmetic condition

but need doctoring if it will be put again in service

 

[val]

2 hours ago, tornfuté said:

hello i open the left side , right side and back of SGLT 100 ,

 

Thank you Pierre, very interesting to see the inside of T100.

[kriegsfunker]

Thank you Pierre.  Very interesting device.   Looks like the big green resistor is the bleed off resistor for the large caps.

[kriegsfunker]

On 08/01/2019 at 13:42, val said:

https://en.wikipedia.org/wiki/Selenium_rectifier

 

Here is a replacement rectifier to hide inside the selenium one.   Any problems with the parameters?

http://www.eicsemi.com/datasheet/RS3FS.PDF

[val]

1 hour ago, kriegsfunker said:

Here is a replacement rectifier to hide inside the selenium one.   Any problems with the parameters?

http://www.eicsemi.com/datasheet/RS3FS.PDF

You should take into the consideration voltage drop first - selenium has high voltage drop and if you

replace it just only with silicon, voltage will be off. See my first pdf link, there's calculation how to add resistor.

[tornfuté]

About Resistor I receive answer from NA8 owner the resistance is 25 k around 40 watts

i have receive dienstschrift of NA8 but must asks if i can put it here

 

[val]

5 hours ago, tornfuté said:

i have receive dienstschrift of NA8 but must asks if i can put it here

It would be very nice if you get a permission for that, since we plan to create

here separate download area for all kind of documents and schematics.

[kriegsfunker]

7 hours ago, tornfuté said:

About Resistor I receive answer from NA8 owner the resistance is 25 k around 40 watts

i have receive dienstschrift of NA8 but must asks if i can put it here

 

Thank you for that information Pierre!   The NA8 schematic would be very nice to have for the restoration.

[tornfuté]

The schematic is very simple  , one transformer for HT and one for LT

a bridge , filter  . Yuri you are right the big resistor in my SGL T 100 must be 

the equivalent of your resistor . In Na8  the owner tell me that the capacitors

must still be original . In notice  i get it’s not  said the value , nor if it’s paper

or electrolytics capacitors, but they are still working 

 

[val]

Pierre thank you very much! Is there in the NA8 manual glimmlampe type mentioned?

[kriegsfunker]

1 hour ago, val said:

Pierre thank you very much! Is there in the NA8 manual glimmlampe type mentioned?

I have been away on business.   I will lightly sand the glimmlampe metal to see if there is any writing there

[tornfuté]

val

      unfortunately    no  reference , no value , i get answer from germany and it's asked  me not to put on internet , i am sorry  but i will respect this  rule

      otherwise  i will not get anything  from him later .

      the notice for  SGL T 100 is  D 943/2