Gene, telling from my rusty experience from waybackwhen (and the RCA transmitting tube manual of 1962) I suspect that the one glowing tube has too much positive DC grid voltage, maybe resulting from a faulty driver (suspect: capacitors). The ouput power you are measuring comes from the other 833 alone which is possible if the circuit is designed for class C operation.
A 833A can carry 1650 W without forced air cooling at 4 kV on the anode so this heating power is probably not all high frequency, but DC anode current, I guess. At less than1 kW it's not yet supposed to glow. The manual says: "At a plate votlage of 4000 V, a fixed bias of at least -90 V should be applied". If the fault occurred suddenly, it won't be a HF balance problem, these more likely tend to sneak in. (I have built an audio band amp with two 807s P-P once upon a time in the early ages of rock'n roll music and dealt a lot with those transmitting tubes.) Peter Am 11.11.2015 11:15, schrieb Gene Heskett: > Then I have to go see if I can restore a 60 yo 1kw Gates BC1 AM > transmitter, again. Something in the feedback loop around the > modulator is causing a severe unbalance in how hard each of the pair > of 833's is working, so one is running bright red and the other is > nearly invisible. No way in tuncket it could ever pass a Proof of > Performance. That, and his < 3/8 wavelength stick is so far out of > tune. I have no clue where the J is, but the effective R is at least > 70 ohms, send out a 1000 watts & the Bird meter says nearly 200 is > coming back. That stick has 2 sets of ICR antennas on it now that > weren't there the last time the doghouse was tuned up. He doesn't > quite grasp that that stuff changes the towers tune. I've been looking > for a GR Bridge, but so few of those were made that anything that > might work is north of $1k USD. None are less than 50 yo. Cheers, Gene > Heskett --- Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft. https://www.avast.com/antivirus ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
