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Novar Spud :: A 0 sweep tube Spud with PCB
Novar Spud :: A 0 sweep tube Spud with PCB
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Old 3rd August 2017, 09:09 AM   #101
murrays is offline murrays  New Zealand
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Does anyone have a good recent supplier for the Novar sockets? I got no response from emailing ESRC1 as per Tom's recommendation. After much Internet searching it appears these are hard to track down.

@tomchr - a suggestion that maybe you could buy a batch of these and offer them through your web store with the boards?

Last edited by murrays; 3rd August 2017 at 09:12 AM. Reason: reformatting
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Old 4th August 2017, 05:20 AM   #102
tomchr is offline tomchr  Canada
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Weird that ESRC doesn't respond. I'd try: www.vacuumtubes.net or eBay.

I generally avoid building inventory as it requires management. I'll see if I can find a good source.

Tom
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Old 4th August 2017, 08:01 AM   #103
murrays is offline murrays  New Zealand
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Quote:
Originally Posted by tomchr View Post
Weird that ESRC doesn't respond. I'd try: www.vacuumtubes.net or eBay.

I generally avoid building inventory as it requires management. I'll see if I can find a good source.

Tom
Thanks Tom, I'll try ESRC again as I just checked their contact details and there is a different email address on the "Contact Us" page from the one on their home page. I used the AOL address on the "Contact Us" page, so I'll give the other one a try.
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Old 5th August 2017, 05:24 AM   #104
tomchr is offline tomchr  Canada
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Toss me an email (through the Contact Us form on my website) if you need my help. I'll be happy to give them a call and ask what their email address is (and whether they have sockets).

Tom
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Old 5th August 2017, 08:14 AM   #105
murrays is offline murrays  New Zealand
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Quote:
Originally Posted by tomchr View Post
Toss me an email (through the Contact Us form on my website) if you need my help. I'll be happy to give them a call and ask what their email address is (and whether they have sockets).

Tom
Thanks Tom. No problem at the moment, as Stan has sent me a reply from the other email address.
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Old 12th August 2017, 05:36 AM   #106
wcakey is offline wcakey
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I have the board and most of the parts I need to complete the build, minus the chassis. I was originally going to go with the 6LR8 version, but depending on your answers to my questions, I might opt for the 6GF7A version instead.

1. Is the output from the 6GF7A version enough to drive my speakers (98 db efficiency)
2. I purchased the 250V Antek tranny. If I used a voltage divider (using 5R and 20R resistors) to get that down to 200V, would that tranny work for the 6GF7A version?
3. If yes to question 2, what wattage would you recommend for the voltage divider resistors?

Thanks in advance for your help.
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Old 12th August 2017, 07:51 AM   #107
Shef is offline Shef
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1. The SE spud on any of your options will give 2+ Watt, enough;
2. Just get a 200V 50VA toroid AnTek on evilBay, there are plenty;
3. Khe-m, let's calculate: P = V * V / R or 250*250/25 = 2,500 Watt. m-m-m, the AnTek trafo might not fit here. .. you could opt for a 2.5 KWa welding one, that's for sure, you will also need a 25A NEMA wall socket. ..and a plug ))
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Old 12th August 2017, 09:18 PM   #108
wcakey is offline wcakey
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Hmm.... Shef, I don't completely understand your answer. I already purchased the recommended Antek power transformer for the 6LR8 version of the amp (Antek AS-1T250 100VA). What I want to know is if it would be OK to use that transformer with a simple voltage divider to get the 200V needed for the 6GF7A version of the amp instead of purchasing the Antek AS-1T200 100VA, which is the recommended transformer for the 6GF7A.

If it is possible to use the Antek AS-1T250 100VA, what should the wattage of the voltage divider resistors be?
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Old 13th August 2017, 01:53 AM   #109
Natural Sound is offline Natural Sound  United States
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wcakey, if one of the other members cant help you might need to wait until after the 24th of August. Tom is on vacation.
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Old 15th August 2017, 03:19 AM   #110
pblix is offline pblix  United States
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Quote:
Originally Posted by Shef View Post
3. Khe-m, let's calculate: P = V * V / R or 250*250/25 = 2,500 Watt. m-m-m, the AnTek trafo might not fit here. .. you could opt for a 2.5 KWa welding one, that's for sure, you will also need a 25A NEMA wall socket. ..and a plug ))
Eh, nowhere close.

Quote:
Originally Posted by wcakey View Post
Hmm.... Shef, I don't completely understand your answer. I already purchased the recommended Antek power transformer for the 6LR8 version of the amp (Antek AS-1T250 100VA). What I want to know is if it would be OK to use that transformer with a simple voltage divider to get the 200V needed for the 6GF7A version of the amp instead of purchasing the Antek AS-1T200 100VA, which is the recommended transformer for the 6GF7A.

If it is possible to use the Antek AS-1T250 100VA, what should the wattage of the voltage divider resistors be?
Here is my estimation, as I don't have a schematic of this amp. I.e. take it for what it's worth.

250VAC rectified with SS with no load will result in 350VDC, give or take.

Assuming 120mA current draw (for both channels), 25V cathode bias, 35V drop over B+ filter & OPT, you're looking at 350-25-35=290VDC between plate and cathode.

You want to bring it to 200V. R=U/I=90/.12=750 Ohm in series with the amp. Actual Power=90*.12=10.8W. A resistor rated for 15W or more should be OK.

HTH
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