Rectifier and max electrolytic Cap

[martin manning]

Easy fix. Goodbye standby switch - or tweak it so its just a mute

I don't follow... The danger from a hot off-on cycle is still there with no standby switch.

[Blackburn]

Easy fix. Goodbye standby switch - or tweak it so its just a mute

I don't follow... The danger from a hot off-on cycle is still there with no standby switch.

I guess the only way this isn't an issue is with the reservoir on the cold side of the standby and not allowing a charge while the rect is still hot and the mains is switched back on? This just goes back to putting the reservoir on the hot side and so on and so forth. It's a cycle.

Diodes!!!

Oops, that's just Miles rubbing off on me.

[martin manning]

I guess the only way this isn't an issue is with the reservoir on the cold side of the standby and not allowing a charge while the rect is still hot and the mains is switched back on?

Reservoir on the cold side of the standby is definitely worse... power on heats the rectifier filament, then you turn the standby to run and you are charging the reservoir from zero volts, hot, every time.

[Blackburn]

I guess the only way this isn't an issue is with the reservoir on the cold side of the standby and not allowing a charge while the rect is still hot and the mains is switched back on?

Reservoir on the cold side of the standby is definitely worse... power on heats the rectifier filament, then you turn the standby to run and you are charging the reservoir from zero volts, hot, every time.

I know, Martin. I was just addressing concern of the mains coming on while the rect is still hot. Guess there's no way to get around a single mains switch and a hot rect. It seems there's sometimes a possible problem with tube rects and some of the ways the ac and dc switching is wired. I like tube rects, but diodes seem like the least problematic way of doing things. I've been using them more lately.

[Blackburn]

Wait, there isn't much of a problem with a single mains switch, a hot rect and a reservoir that's spec'd for the tube, right? Or is all of this kind of hot switching bad? I am referring to turning the amp on right after turning it off with a reservoir that's not over spec. No standby switch.

[Firestorm]

Wait, there isn't much of a problem with a single mains switch, a hot rect and a reservoir that's spec'd for the tube, right? Or is all of this kind of hot switching bad? I am referring to turning the amp on right after turning it off with a reservoir that's not over spec. No standby switch.

The tube manufacturers recommended that if you were going to do that a lot you use a choke input. I suspect that some series resistance with the PT might save you too. The hot switching transient plate current number is between 2 and 5 amps and I think assumed up to 200 milliseconds so even a modest equivalent plate resistance ought to help. Some of the spec sheets even tell you what that resistance ought to be.

[JazzGuitarGimp]

The tube manufacturers recommended that if you were going to do that a lot you use a choke input. I suspect that some series resistance with the PT might save you too. The hot switching transient plate current number is between 2 and 5 amps and I think assumed up to 200 milliseconds so even a modest equivalent plate resistance ought to help. Some of the spec sheets even tell you what that resistance ought to be.

Here is a 1959 GE datasheet for the 5AR4. On the bottom half of page three, under "RATING CHART III", there is a discussion on how to choose the two plate series resistors. Most of it makes sense, though I do not understand the term N.

http://www.drtube.com/datasheets/5ar4-ge1959.pdf

[Guus]

Hi Guy's,

thanks to Firestorm and others for the given technical information.
It gave me answers where I was looking for.
Realy nice to have such a forum.

My next step:
Oh, oh, I did use the 'hot switch' methode in the amp I built.
So, to get less stress on the rectifier tube, I modify the used methode of 'Stand by' switching.

Thanks,

Guus

[martin manning]

Here is a 1959 GE datasheet for the 5AR4. On the bottom half of page three, under "RATING CHART III", there is a discussion on how to choose the two plate series resistors. Most of it makes sense, though I do not understand the term N.

N is the turns ratio from primary to each half of the secondary. N squared times the primary series resistance is the equivalent series resistance of the primary as seen from the secondary.