This problem is caused by bad spot-welds on the anode cooler. When such a tube is used, heating/cooling causes the welds to slowly weaken and break. Triton, the company that bought Eimac's glass tub
? A faster method of determining HV-RFC resonance freqs is to unplug the amp and sweep the choke in place with a dip-meter. - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, www.vcnet.com/measures
? The AL-1500 is the only mfg 8877 MF/HF amp on this planet that does not use a parasitic oscillation suppressor. A friend modeled the 8877 on a computer program for determining amp stability. In a
? sounds a bit too close for comfort. I would try removing 4 turns for starters. ? agreed. cheers, Timo - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, www.vcnet.com/measures. end
? 813s don't need a VHF suppressor because they have virtually no VHF gain. However, this is undoubtedly not the case for the 8877. The last time I talked to Mr. Rauch on the telephone, he told me t
45MHz means he has a long wire from the Tune-C to the 813 anode connection. - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, www.vcnet.com/measures. end
In my experiences, loose joints make a plethora of HF harmonics well up into the VHF region. Thus, finding loose joints can be done with a portable FM receiver. Suitable modulation can be 60wpm dits
? Amplifier to transceiver ALC does not work as advertised. The best solution is to set the transceiver output to a specific level. To drive a 3-500Z to max linear ability, use no more than c. 70w p
? Good point, Mr. Rauch. A friend runs an amplifier analysis program for an engineering company. He plugged in the feedback-C spec and other constants for an 8877 and he found that it could only osc
The new 1200Z7 is less squirrelly than the old A7 version, but the filament V & I needed is higher than a 3-500V. The 8877 has a 5v heater, the same anode V-rating, c. the same drive requirement, bu
New tubes often have more gain than old tubes. More gain is good if one is trying to build an oscillator. To make it oscillate better, remove the VHF suppressors. Does it have Rauchian "neutralizati
Dale makes high-ohm spiral-film resistors. I tested tw5 Dale, 55M-ohm. 5Wers yesterday that performed well at 15kV (4W). The max V ability film resistor I have been able to find at Digi-Key and Mous
Semi-true, however, 1mA in 10M-ohms is 10W which =s 10kV. With 500WV resistors, a series string of 20, 0.5M units would be required. With the 1M-ohm, 2W resistors available from Mouser, the same job