Hi Ed, sounds like a leakage to ground somewhere on the B+ side of the plate supply. Perhaps a HV feed through lost it's insulation or plate bypass or some other component in the B+ circuit has devel
Which can be confirmed by removing the tube(s). 73, Gerald K5GW In a message dated 5/26/2011 5:32:26 P.M. Central Daylight Time, ww4cox@embarqmail.com writes: Last night I was using my 2KD-5, and it
Hi Jim, I have always used a manual "timer" (me) to turn the blower off a couple of minutes after killing hv and filament. My homebrew amps have three power switches; air/water on, filament/heater on
Hi Carl, I have read/heard that about filament transformers before. I am not sure where that idea started but have some doubts about the validity in all cases. The cold resistance of a filament is cl
Hi Pete, I suggest you do more testing before writing off the transformer. One failure scenario that would cause the described problem is a surge limiting circuit that is not shorting out the limitin
Carey, was there a problem you can share info? I can't help with the LCD meter question; I am sure others will though. 73, Gerald K5GW In a message dated 6/6/2011 2:12:25 P.M. Central Daylight Time,
Hsu, are you referring to use of an opto-coupler, such as 4N25? Use of these devices will allow the regulator bridge and FET to be connected to the transformer primary which will reduce current requi
Dave, you might consider adding some current limiting in the transformer primary while testing. A couple of 100 watt incandescent light bulbs in series will work great for that. If all is well, the b
I became interested in filament voltage control after learning how excessive voltage shortens tube life. Then with the power company incrementally increasing line voltage in most areas the concern gr
Any idea about the encoder pricing? 73, Gerald K5GW In a message dated 8/8/2011 4:46:36 P.M. Central Standard Time, maflynn@theflynn.org writes: www.stegmann.com/product/absolute/hollow.html ________
Manfred, are there computer repair shops there? Many of the thermal grease products are targeted for CPU cooling applications. 73, Gerald K5GW In a message dated 8/24/2011 2:19:19 P.M. Central Daylig
Hi Carey, there are number of ways to design meter shunts. A method used by many is to install a low value resistor in series with the circuit and measuring the voltage drop across the resistor with
Here is another example of the need for a hv leakage tester. One can connect the tester between any secondary terminal and the core to determine the suitability of the transformer to operate in a bri
Carey, if the metering circuit is in the cathode lead it can add some bias voltage which will lower the tube gain. You might check the circuit wiring to make sure the meter is between B- and the poin
Most amplifiers meter plate current in the negative plate supply lead which is at or near ground for safety. Strictly speaking, cathode current is the sum of plate and grid currents (plus screen curr
Carel, what is your primary voltage there? Do you have three phase primary power? 73, Gerald K5GW In a message dated 10/25/2011 1:11:15 P.M. Central Daylight Time, pc5m@xs4all.nl writes: Hi, I have t
Hi Mike. back feeding from one secondary to the other may not be such a bad thing. That would force the primary voltage division to the two transformers to be exactly what is needed for equal seconda
Hi Bill, if the primaries were connected in parallel, I would agree with you. But, the in discussion case, the transformer primaries will be connected in series which forces the primary current to be
Hi All, do you think the 40ft moile antenna might have been mounted on one end of the vehicle and pulled diagonally across to the other end and cinched down forming a near half circle? Done that way,
Hi Les, I just went through the same experience with my 2m 8877 amplifier. The amp worked very well over the eme contest but did the big BOOM thing the next time I fired it up, only a couple of days