Luftwaffe NA8 utility power supply for 100 Watt Sender

[val]

14 hours ago, kriegsfunker said:

Does anyone know if there are any effects of running an appliance that worked on German 50 Hz AC power, from an outlet with 60 Hz AC power? 

You are perfectly safe here - increasing frequency by 20% you are actually reducing the stress to transformer also by 20%

Since the transformer was designed to handle 50Hz stress anyway, it will now run cooler and more safer at 60Hz.

If anything will differ - you are only getting 60Hz hum instead of 50 Hz

[kriegsfunker]

NA8 is virtually empty.   All the major parts of the NA8 are out, and restored.  Ready for re-assembly.

 

 

[kriegsfunker]

A modern low voltage rectifier attaches itself nicely to the choke which is located directly under the old rectifier.

[kriegsfunker]

Question about the fuse of this power supply.   The fuse is a push-button type and is rated for 220 VAC / 4.4 Amps.   In the manual, it says that if you switch to 110 VAC, your amperage increases to 8.8 Amps (which makes sense), and they tell you to switch to a fuse that supports that amperage.   I've attached photos of the fuse, and would like to know if I need a new fuse.   Also, the Gluhlampe for this power supply is for 220 VAC.  It probably will not work with 120VAC and I will need a new Gluhlampe.  Should I feed power to this set from a Variac at 220 VAC, or switch the transformers to use 125 VAC?

[val]

36 minutes ago, kriegsfunker said:

Question about the fuse of this power supply.   The fuse is a push-button type and is rated for 220 VAC / 4.4 Amps.   In the manual, it says that if you switch to 110 VAC, your amperage increases to 8.8 Amps (which makes sense), and they tell you to switch to a fuse that supports that amperage.   I've attached photos of the fuse, and would like to know if I need a new fuse.   Also, the Gluhlampe for this power supply is for 220 VAC.  It probably will not work with 120VAC and I will need a new Gluhlampe.  Should I feed power to this set from a Variac at 220 VAC, or switch the transformers to use 125 VAC?

Do you mean Glimmlampe, not Glühlampe? Glimmlampe will work - the transformer primary winding will act as a voltage increasing autotransformer (variac) - see the schematics. Regarding fuse - this is actually automatic circuit breaker - just test it - nothing bad will happen if this circuit breaker is in working order - it will just trip. Test it before, does it trip on 6A?

[kriegsfunker]

1 hour ago, val said:

Do you mean Glimmlampe, not Glühlampe? Glimmlampe will work - the transformer primary winding will act as a voltage increasing autotransformer (variac) - see the schematics. Regarding fuse - this is actually automatic circuit breaker - just test it - nothing bad will happen if this circuit breaker is in working order - it will just trip. Test it before, does it trip on 6A?

I get these two confused  .   Thanks for the guidance.   I will give it a try.

[val]

First test the circuit breaker separately at 6A, if it trips, everything is OK and you will be safe.

If there will be more than 6A - 8.8A as the manual say, then you have either to replace the circuit

breaker or switch to the 220 volt input.

[Funksammler]

I don't think you can get around the current limit, both the bi-metal and the switch itself will be rated to 6A and higher currents will simply cut the switch. I think you will need to find a 10A switch, or bypass it and use a fast 10A fuse to protect the power supply. 

regards,

Funksammler

[Funksammler]

Have a look here: https://www.ebay.de/itm/alte-Siemens-Schuckert-Sicherung-Automat-R-901II-15-10-A-Bakelit-Porzellan-/122885085611

[val]

3 hours ago, Funksammler said:

I don't think you can get around the current limit, both the bi-metal and the switch itself will be rated to 6A and higher currents will simply cut the switch. I think you will need to find a 10A switch, or bypass it and use a fast 10A fuse to protect the power supply.

 

Initial test without a load may even go through - to check the voltages etc. But at full load, yes, i agree with you.

[kriegsfunker]

5 hours ago, Funksammler said:

Have a look here: https://www.ebay.de/itm/alte-Siemens-Schuckert-Sicherung-Automat-R-901II-15-10-A-Bakelit-Porzellan-/122885085611

WOW FS!   This is exactly the item I need.  Thank you so much for finding it.   Now just to see if he will ship to California.

[Funksammler]

4 hours ago, kriegsfunker said:

WOW FS!   This is exactly the item I need.  Thank you so much for finding it.   Now just to see if he will ship to California.

I noticed it is now sold, did you get it?

[kriegsfunker]

I got it.  Just waiting back on shipping details.

[kriegsfunker]

Mounted new silicon rectifier into the old selenium rectifier frame.

 

 

[kriegsfunker]

The NA8 when I got it....

 

And after restoration....

 

Edited March 18, 2019 by kriegsfunker

[Funksammler]

Have you tested it yet? I want to see those RS237's light up!

regards,

Funksammler

[val]

35 minutes ago, Funksammler said:

Have you tested it yet? I want to see those RS237's light up!

 

This will take the whole north america power grid down!

[kriegsfunker]

My dad asked me to test it with him.  I guess he doesn't want to lose his only son.

[kriegsfunker]

A few more pics..

 

 

[kriegsfunker]

It works.  The only part which is not working correctly is the voltmeter.  I have to clean the contacts better and then try it again.

[val]

4 hours ago, kriegsfunker said:

It works. 

Nice work!!!

[kriegsfunker]

Speaking of voltmeters.   Does anyone here have experience on how to fix the internal mechanics of an analog meter?   Looks fairly delicate and easy to screw up.

[kriegsfunker]

I screwed up and blew the meter while testing it.   This is a long shot, but does anyone have a replacement NA8 voltmeter?

Edited March 24, 2019 by kriegsfunker
add picture

[val]

On 19/03/2019 at 23:08, kriegsfunker said:

Speaking of voltmeters.   Does anyone here have experience on how to fix the internal mechanics of an analog meter?   Looks fairly delicate and easy to screw up.

I have repaired before analog meter, but it's indeed very delicate and tedious work.

Everything depends what's actually broken.

[Funksammler]

Can you post a picture of the coil of the instrument, the coding in the corner of the the scale and the back of the housing. Also what is the diameter of the housing? It looks like one of the springs (the spiral bit that connects the moving part to the static part) is burned through... I think your best bet is to find a similar instrument, transfer the scale and fit series resistors to suit. 

regards,

Funksammler