Power Supply for German WW2 Military Radio.
hello I'm Lima Alpha 6 November Charlie Alpha in this video I will try to build a p supply for this uh old radio I received this package from my good friend Hummer hymark it should contain a power supply for Old Tube radios several of these German WW2 radios require 2vt filament volt voltage and 90 volt anode voltage It is Well packed oh this one looks nice it was purchased from Amazon the voltage input is 12 volts which is good filament voltage is good but a node voltage is a little too high now I want to measure the filament voltage I turn down the voltage setting very good it reaches 2 volts which is the correct voltage I have connected a load resistor the voltage is completely stable even with a 2 Amp Load and now I want to measure the anode output I must screw the wrong way there it stopped at 140 vol Vols it's too much I have to go in and change the circuit a bit to get 90 volts here we see that the wiring diagram is divided into two parts high and low voltage I have to change the value of this feedback resistor from 1 Mega to 0.5 Mega I am soldering in a 1 Mega Ohm resistor in parallel with the one that is there incredibly small components I attach it with the soldering iron then I solder it in place with tin solder yes now the voltage is lower another and simpler way is to have a drop resistor and capacitor on the output then it is ready for testing now I want to show how I know which pins should have the different voltages I use an OHM instrument connect the negative terminal to gnd D on the radio one pin shows zero ohms this is the negative filament terminal this is also the Ground Terminal now I will find the positive filament pin this pin is connected to the power switch and shows 1 ohm when the power is on now I want to find the anod power negative pin this pin shows approximately 200 ohms to ground other types of radio will show slightly different values the last pin which is the aode positive terminal it has quite High Resistance then the pins are found without documentation lab power is connected and the signal generator is set to 3,880 KZ with 10 microvolt output the scale shows exactly right 50 after 84 years it is absolutely fantastic I use two separate Powers no Common Ground connection the voltage on the anod negative pin is 1.85 volts this is the grid bias for the entire radio but what happens if we connect the two negative power cables together the anode current increases only [Music] slightly the power from Amazon has common ground the radio still works great the current in the tubs is not too large either goes down to 1 microvolt works well a 1.5 volt battery can be used to generate the negative bias remember that it will then take approximately 8 milliamps of current from the battery works well with 0.2 microvolts
too the conclusion is that it works with common ground possibly that the large signal character istics are getting worse I connect the antenna just CLE what a little boy room sh back down I was just cheing around and then [Music] Common Ground also works well with the antenna [Music] now I want to try the Amazon power for the first time I am sending in a signal of 1 microvolt at 50 on the scale as we hear there is a constant high frequency beeping sound there and then there is noise on some frequencies that's the power we hear here we see the two volts 0.6 volt ripple at 15 khz on the lower bands we hear this rle very [Music] well I connect a 1,000 microfarad capacitor the Ripple disappears [Music] completely I have mounted the Amazon power on a circuit board copper plate here I have connected the power to a torn EB a spectrum analyzer is connected to 90 volts this is the noise from the power unloaded and this is what it looks like under load we clearly hear the noise in the receiver we cannot use this I need to design a filter this is the filter I have found that works well both on 2vt 90 volt negative bias and 12vt input remember that the capacitors must withstand the voltage I will now show how well the filter works with different capacitors all are at 100 Nano farod I normalize the instrument I measure from 1 to 30 MHz the curve vertically is 100 DB I measure 100 Nano farad 250 volt M KT capacitors they work very well down 67 DB at 3.7 MHz slightly less at higher frequencies now I want to test 100 Nano farad ceramic SMD capacitors these can only withstand 25 volts so they cannot be used at the anode voltage fantastic result down 100 DB at 3.7 mahz
[Music] finally I will test out the 33 nanofod 1,000v ceramic also works very well 100 DB down at 3.7 MHz now everything is mounted in the Box all filters are in place the Spectrum analyzer is connected to 90 Vols here we see the background noise this is the idle noise from the power and this is the noise underload very good and it gets even better with the lid on and now I will test the power I send a microvolt signal 3,880 khz I have installed a voltmeter in the radio cables and holes were ready for this we can read both voltages we can heard the weak signal just fine we cannot heard any noise signals Works absolutely great now I want to power the torn. dob1 lab power supplies 2 volts and 130 volts a battery delivers -4.5 volts here is the [Music] connection I am trying to remove negative grid voltage it doesn't work a battery works fine no current flows I have chosen to generate the negative bias voltage from the power supply I rectify the square Pulses from the 2vt part the desired voltage is set on R2 here the components are mounted in the Box the different radios have slightly different pinouts so I have mounted a switch now the power is finished and I'm going out to test it the receiver works fine without power noise [Music] different thing and you know come up with with something that's got the best of in all the previous I will go out and test the power in the field and I will will program the transmitter's frequency I loosen frequency setting number one I will use 3,660 khz uses a frequency counter to find the correct frequency I fix the frequency setting this was also done during the war before going on a mission exact frequency is important I've now taken the trip out in - 8° c nice test of the power here is the power I connect 12 volts to the power I want to use a wire antenna I use a phone for audio in and out of the radio this is the ground plane I will try to throw the antenna up into the trees I use a rock to throw up the antenna the power works great in the cold [Laughter] I'm tuning the antenna [Music] I have moved to a new position the field phone is connected Li five x-ray India Alpha this is Lima alha 6 November Charlie Alpha over Lima Al 6 November Alp Lima Alpha 5 x alha over okay this is Lima Alpha 6 November Char Alpha please give me a report over yeah you are five and n + 10 5 and 9 + 10 over thank you very much 73 Lima Alpha 5 x-ray in the alpha this is Lima Alpha 6 November Char Alpha hour Lio 5 X Al 73 thank you for watching my video if you like it please press uh the Subscribe button and uh please write a comments below thank you camera Maryann mirv thanks to la1 TKA and L 5 xia
2025-02-05 04:07
