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help me please
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28-01-2014, 10:00 AM
The heater voltages add up to 115volts, then you have the voltage drop across the thermistors which are given on the schematic that gives a ball park figure of around 220 volts, plus look at the voltage rating of the HT filter capacitors, plus if you look at the picture of the radios back panel on the radio museum website it states 220v 50-100 Hz.
Lawrence.
28-01-2014, 10:02 AM
28-01-2014, 10:54 AM
Typical current draw for the UCL11 (output section) = 36 ma at a Vg of - 6 volts.
The current draw of the loudspeaker field coil will be around 15 ma so the overall current draw of the receiver should be somewhere around 60/65 ma. Bias for the output valve is developed across the tapped 100 ohm resistor so if receiver current draw is 60 ma then voltage drop across that resistor will be 6v which is correct for the output valve bias voltage. If fitting a silicon rectifier to replace the original selenium then as a ball park figure assume that the selenium rectifier had a forward voltage drop of around 30 volts, if that was the case then that would suggest that the series resistor for the silicon rectifier needs to be somewhere around 500 ohms. If you want to run the receiver at 240 volts ac the I would suggest increasing the value of the rectifier series resistor and also fit a series resistor in the heater chain to drop 20 volts at 100 ma. Lawrence.
28-01-2014, 12:52 PM
The reason I got the Heater chain to 117 Volts was the Data Sheet I looked at - http://frank.pocnet.net/sheets/082/u/UCL11.pdf - lists the UCL11 Heater as 62 Volts.
However, this one lists it as 60 Volts - http://frank.pocnet.net/sheets/076/u/UCL11.pdf. Very odd. Anyway, whats a couple of volts among friends. Alan
28-01-2014, 01:00 PM
Not a lot Alan, at least we have established the mains operating voltage plus a couple of other snippets, I used the ECL11 data sheet for UCL11 operation characteristics eg: anode current, grid bias etc.
Lawrence. |
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