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Re: DO-5 Zener - Re: Zener Diodes in a 5F1 Champ to lowe

12/15/2004 2:55 PM
Peter	Re: DO-5 Zener - Re: Zener Diodes in a 5F1 Champ to lowe Hi, I still haven't received the DO-5 Zener from Mouser, that's why I am asking: >Yes, they come with all the necessary hardware. >It even includes a plastic insulating nut & a mica >washer for isolating the zener from the chassis. >You don't use those in this application. In case of hum I might want to use the insulating nut, so that I can connect the ground side of zener to my central star ground point with a wire, instead of connecting the zener to the chassis. Would that be possible, in other words, does the grounded side of the reverse polarity DO-5 Zener have a solder lug, too?

12/15/2004 2:55 PM

Peter

Re: DO-5 Zener - Re: Zener Diodes in a 5F1 Champ to lowe

Hi,

I still haven't received the DO-5 Zener from Mouser, that's why I am asking:

>Yes, they come with all the necessary hardware.
>It even includes a plastic insulating nut & a mica
>washer for isolating the zener from the chassis.
>You don't use those in this application.

In case of hum I might want to use the insulating nut, so that I can connect the ground side of zener to my central star ground point with a wire, instead of connecting the zener to the chassis.

Would that be possible, in other words, does the grounded side of the reverse polarity DO-5 Zener have a solder lug, too?

12/15/2004 9:28 PM
Ed	Peter- No, it doesn't. So you have to use the body of the DO-5 as the ground point. That's why I originally said to put it as close as possible to wherever the main ground is now. In a later post, you mentioned a lack of open space, but Howard said he fit his close to the PT. As long as it's on that side of the chassis, you should be fine. -Ed

11/28/2004 2:44 PM
Chris @ CMW amps	Re: @Chris - Re: Zener Diodes in a 5F1 Champ to lower B+? Hi Peter To be honest ... my buddy did call me about that amp, I did ask him for some measurements during that telephone-conversation and then did mail him some zeners... so I even didn't see that amp. Normally I do use a small terminal-strip to mount the zeners, be sure to use as much "lead length" as possible because ( even overrated ) they do get somewhat hot. Regarding stripping the heather-wiring: I rarely do work with your mentioned wire, maybe use a regular cutter to re move the fringes? Hope this helps, have fun! Chris

11/28/2004 2:44 PM

Chris @ CMW amps

Re: @Chris - Re: Zener Diodes in a 5F1 Champ to lower B+?

Hi Peter

To be honest

... my buddy did call me about that amp, I did ask him for some measurements during that telephone-conversation and then did mail him some zeners... so I even didn't see that amp.

Normally I do use a small terminal-strip to mount the zeners, be sure to use as much "lead length" as possible because ( even overrated ) they do get somewhat hot.

Regarding stripping the heather-wiring: I rarely do work with your mentioned wire, maybe use a regular cutter to re move the fringes?

Hope this helps, have fun!

Chris

1/19/2005 8:37 AM
marT	Re: Zener Diodes in a 5F1 Champ to lower B+? Hello, I too am building a 5F1 and I have a B+ of 400 volts DC which I want to lower by some 50 volts. Could someone give me a hint on where to get zener diodes in Germany? I tried my usual dealer of choice - www.rs-components.de and they do have zeners, but unfortunately only the expensive magnatec, wich are rated at 20 watts. These are actually very nice, as you can hook them up with a screw and then solder the PT secondary center tap to a little stud coming out of the zener, but the ones they are offering unfortunately have the wrong polarity. All other Zeners I could find were rated at 1.3 Watts and the ratings will of course go down as tubes heat up thanx, mart

1/19/2005 8:37 AM

marT

Re: Zener Diodes in a 5F1 Champ to lower B+?

Hello, I too am building a 5F1 and I have a B+ of 400 volts DC which I want to lower by some 50 volts.

Could someone give me a hint on where to get zener diodes in Germany? I tried my usual dealer of choice - www.rs-components.de and they do have zeners, but unfortunately only the expensive magnatec, wich are rated at 20 watts. These are actually very nice, as you can hook them up with a screw and then solder the PT secondary center tap to a little stud coming out of the zener, but the ones they are offering unfortunately have the wrong polarity.

All other Zeners I could find were rated at 1.3 Watts and the ratings will of course go down as tubes heat up

thanx, mart

1/19/2005 9:25 AM
Chris @ CMW amps	Hi Mart Email me your adres and I'll send you a couple. Chris

1/19/2005 10:16 AM
marT	wow! that's really great! big thanx! Email is on its way...

2/3/2005 1:03 PM
marT	well, here I go again, the voltages are under control, thanks to Chris, who was so kind to send me a couple of zeners. I got the voltages down using 4 zeners wired in series, going from the PT secodary center tap to chassis ground. One Problem remains, which I actually thought was related to the way too high Voltages in my Champ: When I crank the volume up past 2/3 I get a loud buzz / "errrr" sound. Chris gave me some stuff to try out, but the problem remains even if the modifications did make quite some changes, both regarding tone and my "problem". In building my Champ I strictly followed 5F1 schematics, with the addition of a 25uF cap across the first cathode resistor, which is not shown in the schematics. I put up little audio mp3 of what happens when I turn it up - but watch your speakers, things get loud at the end of the file ! http://134.2.42.41/~marten/champ25uF.mp3 Now Chris gave me a hint on using a cap of approximately 1 uF, as you might hear, the buzz is still there, but it is has less low frequency energy. The tone of the amp changed as well, a little less lows and less "open". You can't hear it on the recording, because I had different volume settings, but I preferred the 25uF cap, the way it was originally. This sample is here: http://134.2.42.41/~marten/champ1uF.mp3 The next thing I did was putting a 1k5 gridstopper on the grid of the 6V6. Again the buzzing sound is very differen, just some clicks and the signal is gone, until I back the volume off a little and then it is there again. The tone changed again, getting more two dimensional, I didn't like it. Sample is here: http://134.2.42.41/~marten/champ1uF_gridstopper.mp3 So, if anyone has any more ideas on what is "wrong" with the champ I'd really appreciate that. I checked all tubes, they are fine, voltages are really close to those in the schematics and my assumption is that it's the OT. Apart from that this amp sound really great and I have learned quite a lot from this first diy amp. thanx, marT

2/3/2005 1:03 PM

marT

well, here I go again, the voltages are under control, thanks to Chris, who was so kind to send me a couple of zeners. I got the voltages down using 4 zeners wired in series, going from the PT secodary center tap to chassis ground.

One Problem remains, which I actually thought was related to the way too high Voltages in my Champ: When I crank the volume up past 2/3 I get a loud buzz / "errrr" sound. Chris gave me some stuff to try out, but the problem remains even if the modifications did make quite some changes, both regarding tone and my "problem".

In building my Champ I strictly followed 5F1 schematics, with the addition of a 25uF cap across the first cathode resistor, which is not shown in the schematics.

I put up little audio mp3 of what happens when I turn it up - but watch your speakers, things get loud at the end of the file !

http://134.2.42.41/~marten/champ25uF.mp3

Now Chris gave me a hint on using a cap of approximately 1 uF, as you might hear, the buzz is still there, but it is has less low frequency energy. The tone of the amp changed as well, a little less lows and less "open". You can't hear it on the recording, because I had different volume settings, but I preferred the 25uF cap, the way it was originally. This sample is here:

http://134.2.42.41/~marten/champ1uF.mp3

The next thing I did was putting a 1k5 gridstopper on the grid of the 6V6. Again the buzzing sound is very differen, just some clicks and the signal is gone, until I back the volume off a little and then it is there again. The tone changed again, getting more two dimensional, I didn't like it. Sample is here:

http://134.2.42.41/~marten/champ1uF_gridstopper.mp3

So, if anyone has any more ideas on what is "wrong" with the champ I'd really appreciate that. I checked all tubes, they are fine, voltages are really close to those in the schematics and my assumption is that it's the OT. Apart from that this amp sound really great and I have learned quite a lot from this first diy amp.

thanx, marT

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