Golden Eagle 750 plate voltage

[bluemeanie]

I have a two part question. First off I have been told that originally these amps were made for the 27lf6 and the supply dried up and they put the 20lf6 in with no changes. if that is true is there a way I can take maybe a voltmeter and check it without frying myself. It throws high swrs to the radio, isn't there a component that causes that? I am recapping it and while I'm digging around in there would like to address that as well. Thanks In advance.
Mark

[Night Crawler]

The only difference between the two tubes is the filament voltage 27LF6 (27 volts) and the 20LF6 (20 volts) that is required to heat the tube the same plate voltage will work with either tube.

So if the 20LF6 was used to replace the 27LF6 without any changes to the filament supply voltage that means those tubes are getting 27 volts to the filaments which is 7 volts more then needed to heat the tube.

That would be like using 127 volts instead of 120 volts on a 60 watt lightbulb which would result in premature failure of that bulb.

To check what the filament voltage is use a voltmeter on the 50 Volt AC scale and put the two probes on pins 1 and 12 of one of the tube sockets that will tell you how much filament votltage it's getting.
You can remove the tubes when doing this and leave it on standby if you remove the tubes make sure the plate caps aren't making contact with anything that's where the lethal voltage is.

What you can do to lower the swr between the radio and amplifier is use a tuned input circuit going to the input of the tubes if there is one already in the amplifier all that has to be done is adjust it.

[bluemeanie]

With help from lots of people was able to check the voltage from pin 1 to pin 12 and sure enough the answer is 28.5 volts. I recapped the linear, every capacitor I could find in it I changed. Also not sure if this had anything to do with but I replaced my old A99 with a Max 2000 and low and behold the SWR back to the radio is a respectable 1.5 now. So I guess for building a spare set of tubes I'll look for 26lx6 now. Thanks all.

[liquidh8]

Interesting thread. I have seem somewhere online where a fellow was having real high filament voltages on his eagle 515. I too have a 515 and never though to check something like that, considering my house has like 129 volt at the outlet, lol.

[Night Crawler]

If you have a 129 vac line voltage it will not only increase the filament voltage but the plate voltage as well.

[bluemeanie]

I have been told that all of the kenrich amps are this way. check the heater voltage and probably be suprised.
Mark

[liquidh8]

If you have a 129 vac line voltage it will not only increase the filament voltage but the plate voltage as well.

i know I have a high line voltage. I was chasing an issue with a KLV550 I was rebuilding, kept blowing out regulators for the bias circuit. The circuit had fixed value parts and with the high voltage, it was too much. I ended up making a separate regulator for that circuit.

In any case, i have to figure out a way to get the line voltage down to 110.

[bluemeanie]

Call the power company that's not right bet there's a transformer somewhere messn up

[Slyguy]

Call the power company that's not right bet there's a transformer somewhere messn up

Yep. That's what I would do. Tell them its burning up your electronics and they'll show right up. Worked for me when I had horrible 60hz noise in my receive.

[liquidh8]

Yeah, I could do that. PECO is a PITA though around here. I just haven't been running that amp just in case.