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Old 3rd November 2008, 05:32 PM   #21
n_maher is offline n_maher  United States
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Ty,

Since you have the simulation already setup at what point would the capacitance become intrusive?
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Old 3rd November 2008, 08:53 PM   #22
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Probably somewhere between ten to twenty feet of cable at 31 pF per foot.

Isn't the formula something like F = 10 / (2 * pi * Rg * C)? That would put 31 pF at 100 KHz, and 310 pF at 10 KHz. I'm assuming there is a 500K ohm grid resistor at the first input tube. Changing that will affect the results.
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Old 4th November 2008, 12:15 AM   #23
N1ESE is offline N1ESE  United States
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PCB arrived today from George. Gotta love how fast it got here from Florida (shipped on Saturday).

All other parts have shipped from the respective suppliers EXCEPT for the Edcors. They didn't have any CSXE25-8-5K's on the shelf and they will have to be built.
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Old 6th November 2008, 11:18 PM   #24
N1ESE is offline N1ESE  United States
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Not much progess has been made since the board arrived on Monday. I think USPS was teasing me by getting the board to me so fast as the rest of the parts are now running late. Majority of the board components were shipped from Mouser on Monday via Priority Mail and they still aren't here yet.

So far, I've only received the FREDS and a couple caps from DigiKey and my ASC cap from Allied. Everything else is "on the way".

I do have one pic I can share though:

Click the image to open in full size.Click the image to open in full size.
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Old 7th November 2008, 04:04 AM   #25
N1ESE is offline N1ESE  United States
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Quote:
Originally posted by N1ESE
So far, I've only received the FREDS and a couple caps from DigiKey and my ASC cap from Allied. Everything else is "on the way".
Slight correction. I received the CCS ICs not the FREDs. I forgot to order the FREDs because they weren't on Ty's parts list and I was an idiot.

However, if I never have any intention on running with solid state rectification, do I need to install the FREDs?

Thanks
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Old 7th November 2008, 10:57 AM   #26
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If you have no intention of running with solid state rectification, there is no need for the FREDs. Just leave the holes on the board empty.
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Old 7th November 2008, 12:04 PM   #27
cjkpkg is offline cjkpkg  United States
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I blew the FRED's when my PT shorted and I never put them back in...

In fact my B+ was a little high when I used the FREDs anyway so using tube rectifier drops it down just enough.

I am using the Allied 6K7VG 750V center tapped.
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Old 7th November 2008, 01:49 PM   #28
n_maher is offline n_maher  United States
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I installed them as a just in case option if I ever have the amp away from home and have a rectifier tube go south. They're cheap and don't hurt anything to have installed do they?
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Old 7th November 2008, 05:28 PM   #29
cjkpkg is offline cjkpkg  United States
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I think it is a matter of personal preference. Some prefer tube some prefer SS. Certainly wont hurt anything - unless they get cooked - then they will need to be removed.

When my FREDs died I just cut them out and never replaced them.

I would just plan to have a spare 5AU4 around.
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Old 7th November 2008, 05:33 PM   #30
N1ESE is offline N1ESE  United States
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Thanks Ty, Nate, et al. Good to know I'm not dead in the water without them. I just wanted to confirm that I could run the amp without them installed. I will likely add them later just because but I'm not about to make a special order just for two diodes. I'll wait til I need some more stuff from DigiKey or Mouser to justify the shipping expense.

Meanwhile, USPS just delivered my KT88's and some used EL34's (for testing) along with all the board components from Mouser.
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