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Luftwaffe NA8 utility power supply for 100 Watt Sender


kriegsfunker

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After a year of waiting, I got this power supply.  It weighs around 90 KG and broke my hydraulic hand-truck moving it to the shelf.   It looks complete inside, so I will restore it  (slowly).

 

 

 

Screenshot from 2018-12-29 16-37-58.jpg

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Yeah, definitely doctored, and stripped.   Here's my interior.  It's definitely restorable, which I've started doing now.

 

 

Screenshot from 2019-01-01 13-19-00.jpg

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Most of the weight is in the transformers.   Behind the selenium rectifier array, there's a double winding massive transformer which probably weights 1/2 of the device.  There are 4 other transformers in there as well.

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Nice one! I like that you can adjust the output power of the transmitter by setting the anode voltage. The vehicle power supply does not have this facility, it just generates 1000V. The NA6 was often used with the 100 W.S. and a Morseschreiber as a Luftwaffe beacon station. The luftwaffe multi engined aircraft could use their PeilG6 radio direction finders to navigate using these beacons.

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Thanks FS.  The AC input voltage can be changed by connecting to the appropriate terminal on the input transformer.

Screen Shot 2019-01-02 at 9.01.11 AM.JPG

This will also allow me to finally build a tube tester for the RS-237.

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A few years ago, I was offered one of these.   The insides are a bit different.  Notably, the selenium rectifiers are different.

DSCN0690.JPG

DSCN0691.JPG

DSCN0697.JPG

DSCN0699.JPG

Edited by kriegsfunker
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Yuri - one special request please - when you start restoring it, show what type of Glimmlampe there is.

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Hello to all you technical experts,

I just wondered where on earth do you find these superb radio sets etc....I would have thought most would have been destroyed after WW2 but it seem there are many more to be found...Good Luck!

Thanks for showing us on MCN these rare and great memorable items.

Desert Rat

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2 hours ago, val said:

Yuri - one special request please - when you start restoring it, show what type of Glimmlampe there is.

Of course!

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6 hours ago, val said:

Yuri - one special request please - when you start restoring it, show what type of Glimmlampe there is.

Do you have one of these?

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Here's a photo from a field manual showing the NA8 installed in some vehicle. Note the different locations of the power terminals:

 

 

Screenshot from 2019-01-03 22-22-32.jpg

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On 03/01/2019 at 04:17, kriegsfunker said:

Do you have one of these?

No, my friend has one.

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18 hours ago, val said:

No, my friend has one.

Here is the lamp

 

 

Screenshot from 2019-01-04 21-45-26.jpg

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Val - please ask your friend to measure the resistor on top of the huge capacitor under the transmitter power output terminals.  My resistor is dead.

 

Screenshot from 2019-01-04 22-01-21.jpg

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8 hours ago, kriegsfunker said:

Here is the lamp

Thanks! Any visible markings there?

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On 05/01/2019 at 08:03, kriegsfunker said:

Val - please ask your friend to measure the resistor on top of the huge capacitor under the transmitter power output terminals.  My resistor is dead.

Asked - sorry, his set missed that resistor alltogether :(

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What resistor value would you use for a "bleed-off" resistor on a 32 uF 1.2 kV capacitor made for 1000 Volts DC at 250 mA?

Edited by kriegsfunker
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59 minutes ago, kriegsfunker said:

What resistor value would you use for a "bleed-off" resistor on a 32 uF 1.2 kW capacitor made for 1000 Volts DC at 250 mA?

If i have to guess i'd use something around 10MΩ as a permanent bleeder.

This would give a slow discharge something between 5...10 min.

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Based on the following calculations, I'm buying this resistor:

 

Screen Shot 2019-01-07 at 4.24.10 PM.JPG

Screen Shot 2019-01-07 at 4.24.23 PM.JPG

Screen Shot 2019-01-07 at 4.24.34 PM.JPG

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You probably want to give the resistor clamps a good clean, I find it hard to believe that the resistor wire (embedded in glaze) is defective. It looks like the clamps just connect to the wire by pressure...

regards,

Funksammler

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