Ron Wagner <[EMAIL PROTECTED]> made an utterence to the drakelist gang
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Dave,
The loss of the bias on any amp with it keyed would do some major damage. Think about it a minute, the bias is a negative voltage that is designed to "hide" the large positive plate voltage from the cathode. Without that negative grid "hiding" the plate, the tube goes into full conduction. As much power as the power supply can produce will be run into the 6JB6s. Keep in mind that the AC-x supplies could provide well into the 300+ watts input into the rigs finals.
A 3-500 going "full bore" without bias would "blow up" fairly quickly too. It is that the loss of bias also keys the rig in the Drakes. That turns the 6JB6s on full and very quickly turns the tubes bright red and then crack, or implode.
I have not really paid a lot of attention to any tube radio other then Drake, so I am going out on a limb here. I would think the same kind of thing would occur to a Heath, Kenwood, Yaseu, Collins ....... if their bias supply shorted and did not get their plate voltage shut down (ie blown fuse).
73, Ron
============================================================ Visit my astronomy home page. http://www.dma.org/~wagner Amateur Radio Station: WD8SBB - Ron and KB8NRP - Joann ============================================================
On Wed, 2 Feb 2005, Dave Meadows wrote:
"Dave Meadows" <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- Keith: Thanks for asking what I've been asking in the back of my mind. I've heard that if the bias supply goes the radio fries and other such dire predictions. I've worked on lots of vintage gear and have had power supply filter caps short out and over heat transformers and take out a resistor or two but never had the actual "working" part of the gear harmed because of it. Maybe there's a first time for everything. Dave Meadows - K4LDI
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