Restoring my first 100W.S. to use for amateur radio operations

[kriegsfunker]

Folks - I'm restoring my first 100W.S. to use for amateur radio operation.   For those who successfully restored it, do you have any advice on the best way to proceed and what to check and test?

 

[Funksammler]

I am still sorting out some niggles on my 100 W.S. First of all the bearings in the tuning circuits needed greasing, which involves removing the frequency scale to get access to the front ones. Another issue I had was a badly set telegraphy relay, so be sure to check it is working properly...

regards,

Funksammler

 

[kriegsfunker]

Thank you FS.   Do you care about the asbestos lining on the vacuum tube retention caps?  Or is that not too dangerous to have around?

At what power do you operate the transmitter, and at what frequency?    Here in the USA, we are only allowed to transmit from 472-479 KHz with only 5 watts of power.

Also, when the transmitter operates at low power (10 watts) when the Leistung is switched to "Klein"", is that the 100WS which is reducing the 1000V of anode voltage, or do you have to supply 100V to make it 10 watts?

Edited July 1, 2019 by kriegsfunker

[kriegsfunker]

Any advice on the best lubricant for tuning gears?   Something similar to what was originally used, but not corrosive to the metal.

[kriegsfunker]

Any ideas about removing the fine-tuning frequency knob?   The screws are frozen.

[Funksammler]

The Asbestos is best touched as little as possible, certainly don't do anything to is that might cause loose fibres to escape. I power the 100 W.S. through a U100, since I only use it with a dummy load (KA100) I am not worried about restricting the power. Long wave is completely unusable here for amateur use due to ADSL interference anyway, so using it in a QSO is out of the question. 

Rather than replace the grease, I revitalise the old grease with thin oil (WD40 or equivalent). Grease consist of oil in an emulsifier (typically a soap), they harden because the light ends of the oil evaporate over time. By adding thin oil and working the bearing you mix the light ends back into the grease giving it a new lease of life. The big advantage of using this method is that it prevents you having to take the bearings out for cleaning and re-greasing so you won't have to dismantle the complete transmitter.

Use penetrating oil on the screws of the frequency tuning knob and be patient. They should come undone eventually...

regards,

Funksammler

[kriegsfunker]

Thank you FS.   We can communicate on 472-479 KHz here with a max output of 5 watts.   I am building a 1/4 wave 600 meter meander dipole antenna for this purpose.  If I can get 5% efficiency from this antenna at 100 watts, I will be happy.

[kriegsfunker]

Here is the picture of the strange frequency fine-tuning knob.   It looks like the screws have been countersunk into soft material, and the knob hardened around them.   Really strange look.   I can't see how I can even unscrew these.

 

 

[kriegsfunker]

Got them off.   Heating with soldering iron combined with gently hammering the edges of the screw slits.

[kriegsfunker]

Did i mention that unfreezing these old screws is my most favorite part of this hobby?

[kriegsfunker]

After successfully testing tube sockets without load, I inserted two American VT4C tubes (didn't want to risk the RS-237s), and an RS-241.   Connected the transmitter to the dummy load (KA 100 b)vand NA8.   Turned on the power, and got good filament voltage.   15 V on the NA8 and adjusted the Heizung knob to read 10.5 on the 100W.S. voltmeter.  The two power triodes started to glow.   Connected the telegraph key and switched the anode voltage to 800 volts on the NA8.   Keyed the transmitter and got no deflection on the antenna power meter.   The 100W.S. voltmeter showed anode voltage was on in the transmitter.   Something must be wrong with the antenna circuit, so I will investigate that tomorrow.   But this is good progress.

 

 

[val]

On 04/08/2019 at 09:44, kriegsfunker said:

 Something must be wrong with the antenna circuit, so I will investigate that tomorrow.   But this is good progress.

Not necessarily, it could be also fault in keying / control circuit. There's lot of

capacitors that could become bad in passing time.

For testing try telephony, audio is routed directly via two transformer and one coil to grid.

 

[kriegsfunker]

After some testing, determined that the master oscillator and power amplifier work fine.   Got a 0.7 A current on the antenna power meter with the dummy load.  Troubleshooting the keying / control circuit.   Since I can only use CW for 472 KHz.

[kriegsfunker]

OK, the transmitter works!  Now to build the antenna!

https://photos.app.goo.gl/TRxNUxKoteDhHBqk9

Edited September 25, 2019 by kriegsfunker

[val]

1 hour ago, kriegsfunker said:

OK, the transmitter works!  Now to build the antenna!

Nice! What was the problem?

[kriegsfunker]

In reality, there was really nothing I had to do to fix it.   

1)  There are many contacts where there are copper selector blade switches.  All of them had to get cleaned.

2)  The voltmeter was not showing anode voltage correctly, so it had to be taken apart and cleaned

3)  The transmitter had to be disassembled into 3 modules (HF, Antenna, and control) and the contacts had to be cleaned between them

4) When taking apart the antenna module from the control module below, make sure to set the main switch (Empfang, Aus, Telegrafie, Telefonie) to Aus, and make sure to change it back to "Aus" when reassembling the modules.   That main switch also controls the antenna switch in the antenna module and has to be coordinated with that switch, or the power will not get to the antenna connector.

5) I removed the relay from the remote-keying relay box, because it was making the transmitter operate in Telefonie mode incorrectly.

In general, the 100W.S. worked almost perfectly 79 years after it was made.   Not bad.

 

[kriegsfunker]

What does this capacitor do?  Called the "Neutralizationskondensator"  It tunes some sort of capacitive coupling between the two RS-237 tubes, but I don't understand what the manual says about it.   It is accessed by unscrewing the large screw under the heat vent of the tube compartment.  Then you insert a screwdriver into the hole through the RS-241 tube socket to tune it.

 

Edited September 29, 2019 by kriegsfunker

[kriegsfunker]

OK, I found something.  Here is the translation from German:

"The power stage is neutralized by means of the capacitor (62) to prevent self-excitation by the inner tube capacity. The naturalization capacitor is set in the factory for the specified type of tube during the testing of the transmitters and must not be readjusted even when the tube is changed."

 

[kriegsfunker]

Another positive for this transmitter is that there are very few electrolytic capacitors.  Most of the capacitors are these early sandwich types which don't go bad with time.

[kriegsfunker]

Question for anyone here who actually succeeded to transmit on the 630 meter band.  I have been trying to talk to people very close to my home (60-90 km) and have not succeeded.   I have a 80 meter dipole, and have tuned to 100WS variometer to get maximum antenna current of 3-4 amps, but no one can hear my signal.   I will try something else tomorrow - I'll solder both halves of the dipole together and see if that works better.

[val]

Try this.

http://www.wd8das.net/630mPractical.pdf

and also look at those links

http://www.472khz.org/pages/and-more/useful-links.php

[kriegsfunker]

Setback yesterday.  NA8 failed.   Will look at it this weekend.

[val]

5 minutes ago, kriegsfunker said:

Setback yesterday.  NA8 failed.   Will look at it this weekend.

Which voltage failed?

[kriegsfunker]

High voltage failed.  Sparking next to the new HV rectifier, and it burns out the rectifier.   Some component has failed - I hope one of the filter caps.

[kriegsfunker]

OK - it works again.  My own soldering failed, and the connection broke between the HV transformer and rectifier.   Looks like the wiring really heats up during use, and this temperature-stresses the solder and connections.  I found 2 solder spots that have failed, and fixed them.