N1OHN
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« on: July 19, 2015, 12:48:53 PM » |
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hello all  I'm wondering if someone that has completed the level II audio mods from K6AD can help me. I'm confused on some of the capacitors values. 1) the cap labeled 390 across the transformer driving the two 807 is this 390uf, .390uf, .390pf, or 390pf? Also no polarity is given making me think that this is a film or ceramic cap. no voltage is given. 2) Same problem as in question one the cap labeled 62 to ground off of pin five of V2. Thanks all  |
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DMOD
AC0OB - A Place where Thermionic Emitters Rule!
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« Reply #1 on: July 19, 2015, 02:20:10 PM » |
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Which Mod and which Schematic?
There are dozens out there, some good, some bad.
Phil - AC0OB
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N1OHN
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« Reply #2 on: July 19, 2015, 02:23:55 PM » |
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Hi Phil
This is the Level II mods in the Electric Radio magazine from k6ad. Number 110,111,112 in electric radio.
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DMOD
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« Reply #3 on: July 19, 2015, 03:05:59 PM » |
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I don't have those issues of ER (I do write articles for them) but I suspect those are 390 pF ceramic rated at 1kV.
Phil - AC0OB
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Charlie Eppes: Dad would be so happy if we married a doctor. Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse. NUMB3RS |
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VE3AJM
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« Reply #4 on: July 19, 2015, 03:23:24 PM » |
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I'm looking at the schematic. Looks like a 390pf in series with a 330 ohm resistor across the grids/secondary of the driver transformer of the 807s.
I don't see the other cap you mentioned labelled 62 off pin5 of V2 to ground.
Al VE3AJM
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N1OHN
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« Reply #5 on: July 19, 2015, 03:36:17 PM » |
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Hi Al
Yeah I think is a 390pf ceramic also....The diagram your looking at is for the Level I mod however the 390 cap is the same. The .33 to ground in your diagram was changed to a 62 something in the level II mod.
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VE3AJM
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« Reply #6 on: July 19, 2015, 03:45:11 PM » |
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I'll have a look at the later Mod 2.
Al
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N1OHN
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« Reply #7 on: July 19, 2015, 03:47:26 PM » |
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Thanks Al .... its in the book #111
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VE3AJM
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« Reply #8 on: July 19, 2015, 03:54:06 PM » |
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Looks like 62pf 1kv rated at least.
Al VE3AJM
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N1OHN
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« Reply #9 on: July 19, 2015, 03:56:25 PM » |
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Thanks!! should I use mica or ceramic .... probably don't matter?
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VE3AJM
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« Reply #10 on: July 19, 2015, 03:59:06 PM » |
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Either type with the suitable voltage rating. Use what you have on hand or can get easy access to I would say. Cool mod for the Viking 2.
Al VE3AJM
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N1OHN
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« Reply #11 on: July 19, 2015, 04:00:30 PM » |
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Ok Great!!!!
Thank you Al and Phil!!!!
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DMOD
AC0OB - A Place where Thermionic Emitters Rule!
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« Reply #12 on: July 20, 2015, 11:10:42 AM » |
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It appears the 20k resistor across the secondary is a "damper" to dampen out transients and to load the secondary.
The series 330 ohm resistor and 390 pF cap has a -3dB point at 1.2 MHz to "snub" any transients with frequencies from 1.2MHz on up.
Phil - AC0OB
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Charlie Eppes: Dad would be so happy if we married a doctor. Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse. NUMB3RS |
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