Yes you should probably see like 4v across the resistor. My guess is that these will run around 10ma. But it will be interesting to see how well matched each tube and section are.
I have to do this tomorrow. Not home right now. But these "new" russian tubes were matched with a tube tracer by a swedish guy i know (Göran) so i think it should be pretty close. But still, exciting 🙂 let's see 🙂
Now it's bedtime for us on the other side of the pond 😉
/Johan
Now it's bedtime for us on the other side of the pond 😉
/Johan
One question more, you say i should see about 4volts here. That means when i test with my tester it have to be set on "V" not on mA cuz mA reading i get from calculation right?
Maybe a stupid question hehe😉 better safe than sorry🙂
Maybe a stupid question hehe😉 better safe than sorry🙂
Yes, be careful with the meter, having some meters on the wrong setting or configuration connected to high voltage could be bad.
Attach the one or both leads safely with an alligator clip and take your measurements one handed.
Yes volts not amps for your multimeter.
You calculate amps via ohms law V=I*R. Amps is I=V/R so you divide your voltage by cathode resistor value.
You can't measure amps easily with your multimeter without drastically modifying the circuit. Ohms law makes it very easy for us in a non intrusive way.
You calculate amps via ohms law V=I*R. Amps is I=V/R so you divide your voltage by cathode resistor value.
You can't measure amps easily with your multimeter without drastically modifying the circuit. Ohms law makes it very easy for us in a non intrusive way.
I have measured and got first tube to 1,44v over both 470R and the other slightly lower, 1,40V on both.
1,44V/470R= 0,00306
1,40V/470R= 0,00297
Math have never been my strong thing =) But this seems very low?
1,44V/470R= 0,00306
1,40V/470R= 0,00297
Math have never been my strong thing =) But this seems very low?
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Actually voltage was showed with a minus before value on my display whatever setting i choose (2V/20V/200V)
so -1,44 vs. -1,40 is correct.
so -1,44 vs. -1,40 is correct.
So you are running only at 3 mA then. If it were me I would drop the cathode resistors down to like 270 or so. from the data sheets looks like around 8mA is a good target.
Keep dropping your cathode resistor until you reach at least 8mA but I would not go over 10.
Keep in mind b+ will drop a little as you increase the current.
Keep dropping your cathode resistor until you reach at least 8mA but I would not go over 10.
Keep in mind b+ will drop a little as you increase the current.
Ok after looking at the data sheet a little more even 8 looks a little high...I would shoot for 5mA so maybe start with 330 ohm cathode resistors...make sure you do both sections. You can however do one tube at a time.
Ok I soldered 330ohm in place (all four places) and volt is now 1,13 vs 1,17 so that should be 3,5mA?
Lower even more then?
B+ went down little, from 211 to 208V.
Everything is measured idle not under load/music? That is correct to do?
Lower even more then?
B+ went down little, from 211 to 208V.
Everything is measured idle not under load/music? That is correct to do?
ok...it went up a little...keep going...try 270
Yes, idle is best so there is no fluctuating A/C going through the circuit.
I always like to run my tubes "hot" I think they sound the best that way
Yes, idle is best so there is no fluctuating A/C going through the circuit.
I always like to run my tubes "hot" I think they sound the best that way
Yes i thought so too.
Do I put more pressure on transformer doing this? Making the tube hotter i mean. It is pretty hot as it is.
I noticed tubes are a bit hotter now on the sides then before. and maybe it actually sounds at bit more open? not sure. Listen only half hour on it. Before i noticed that after 3h+ sounds opened up more.
I will try lower tomorrow. If i have some value that fits (serie or paralell it have to be) 270 i don't have in stock.
Do I put more pressure on transformer doing this? Making the tube hotter i mean. It is pretty hot as it is.
I noticed tubes are a bit hotter now on the sides then before. and maybe it actually sounds at bit more open? not sure. Listen only half hour on it. Before i noticed that after 3h+ sounds opened up more.
I will try lower tomorrow. If i have some value that fits (serie or paralell it have to be) 270 i don't have in stock.
By "hotter" I meant more current, but yes as you run more current through the tube will actually get hotter.
What rating is your transformer? in VA or Amps for the HV secondary?
Usually pulling a few more mA out of the xformer is not a big deal. My guess is that you have plenty of headroom. We are only talking less than 20mA total.
Also you can parallel resistors to get a lower value - google parallel resistor calculator and you can see if you have the right values to combine to get the value you desire.
What rating is your transformer? in VA or Amps for the HV secondary?
Usually pulling a few more mA out of the xformer is not a big deal. My guess is that you have plenty of headroom. We are only talking less than 20mA total.
Also you can parallel resistors to get a lower value - google parallel resistor calculator and you can see if you have the right values to combine to get the value you desire.
It's total 30va. When i measured powerconsumption from wall it's 17-18W max.
Amp:
0,04A for 230 secondary
6,3v =0,7 and 1,5a
According to seller...
Amp:
0,04A for 230 secondary
6,3v =0,7 and 1,5a
According to seller...
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Ok good to know!
I checked my resistor storage and i can get 250. I will try that.
Another thing mentioned earlier that i really want to know is that how big/small coupling caps do i really need ?
Is 0,33 on input and 3,3uf ok? It feels like it's little "cut-off" under say 40-50hz.
I'm about to order some new ones.
Any ideas?
Also want to try a choke. Is 20mH to much? Do i replace this with the 10k resistor?
Thx
I checked my resistor storage and i can get 250. I will try that.
Another thing mentioned earlier that i really want to know is that how big/small coupling caps do i really need ?
Is 0,33 on input and 3,3uf ok? It feels like it's little "cut-off" under say 40-50hz.
I'm about to order some new ones.
Any ideas?
Also want to try a choke. Is 20mH to much? Do i replace this with the 10k resistor?
Thx
Here is what I would try.
1. No input cap...use 330 ohm resistor instead...grid stopper can help reduce/eliminate oscillation.
2. 5 or 10 H choke in place of the 100R in the psu...you need to keep the 10k in the second spot to drop enough voltage. Choke goes in the first spot.
3. For output cap use high quality film or pio cap...anything from 0.33uF to 1uF is good here. You could even bypass a nice film cap with a pio cap too(parallel).
SRPP+ PCB & Death of the CD this is a good read on srpp circuit.
1. No input cap...use 330 ohm resistor instead...grid stopper can help reduce/eliminate oscillation.
2. 5 or 10 H choke in place of the 100R in the psu...you need to keep the 10k in the second spot to drop enough voltage. Choke goes in the first spot.
3. For output cap use high quality film or pio cap...anything from 0.33uF to 1uF is good here. You could even bypass a nice film cap with a pio cap too(parallel).
SRPP+ PCB & Death of the CD this is a good read on srpp circuit.
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