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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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16th Sep 2018, 7:53 pm | #1 |
Hexode
Join Date: Mar 2018
Location: Bishop Auckland, County Durham, UK.
Posts: 373
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Advance E2 signal generator
I bought this generator as untested from an Internet auction site and decided to have a quick look inside before plugging it in. The 6X5 rectifier valve was missing and closer inspection revealed a vintage modification consisting of a metal "top hat" silicone diode wired from one of the anode pins to the main smoothing can. The 6X5 is connected as a half wave rectifier in this model. The repairer had thoughtfully included a surge limiting resistor in series with the diode but had inadvertently bypassed a 560 ohm resistor that had been in series with the valve's cathode. I fitted a used 6X5 and restored the circuitry to it's original state. Switching on produced RF output, tested by plugging a short length of wire into the output socket and placing a transistor radio nearby. However there was no AF modulation tone or any AF from the output socket. The Advance uses one half of a 6SN7 double triode for an AF oscillator, with the other triode used as HT regulator and modulator for the RF circuits. Following advice on this forum I replaced the two .05uF capacitors connected to the AF oscillator transformer, using 1000v types. This restored full operation.
I noticed when testing at VHF that with a short piece of wire connected to the "full RF" output socket, I could easily wipe out a transistor radio 30 feet away that was tuned to our local FM station. A little RF can go a long way.
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Regards Martin |
16th Sep 2018, 8:26 pm | #2 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,571
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Re: Advance E2 signal generator
These are great little generators. I wouldn't mind betting that if you check it with a frequency counter, you'll find it pretty accurate.
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