- 1. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Jim Garland" <4cx250b@muohio.edu>
- Date: Sun, 7 Feb 2010 08:25:54 -0700
- Great comments, Jim and Roy. Two points. First, my 8877 Amp, described in several editions of Orr's book, was designed and built in the late 1970s. In it, as Jim noted, I used a vacuum relay to inter
- /archives//html/Amps/2010-02/msg00183.html (11,438 bytes)
- 2. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Paul Christensen" <w9ac@arrl.net>
- Date: Sun, 7 Feb 2010 10:55:55 -0500
- Many commercial amps use a 25-ohm @ 25W resistor in the B+ line between the filter cap and the anode(s). If regulation as a result of IR drop was an issue with R placed in front of the filter C, (and
- /archives//html/Amps/2010-02/msg00184.html (13,111 bytes)
- 3. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: Ron Youvan <ka4inm@tampabay.rr.com>
- Date: Sun, 07 Feb 2010 16:02:14 +0000
- I don't understand why putting the 25 Ohm resistance in one transformer secondary lead wouldn't serve all needs, turn on surge (cap. charge), control arc and shorted condition overload and current l
- /archives//html/Amps/2010-02/msg00185.html (8,867 bytes)
- 4. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Carl" <km1h@jeremy.mv.com>
- Date: Sun, 7 Feb 2010 11:14:40 -0500
- Id still use a 2nd resistor as a HV glitch resistor for the tube. The one at the PS input has no effect on a tube arc at the critical moment. Ive yet to see any commercial amp, ham or otherwise use a
- /archives//html/Amps/2010-02/msg00186.html (15,481 bytes)
- 5. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Paul Christensen" <w9ac@arrl.net>
- Date: Sun, 7 Feb 2010 11:21:57 -0500
- Thinking it through a bit further, a 25-ohm surge R placed between the filter C and anode(s) only results in 25V drop at 1A of Ip. So, in relation to a 3-4KV supply, that's insignificant. However, wi
- /archives//html/Amps/2010-02/msg00187.html (15,541 bytes)
- 6. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Jim Garland" <4cx250b@muohio.edu>
- Date: Sun, 7 Feb 2010 10:44:34 -0700
- secondary and shorted are fuses. broadcasting industry chairman of CBS The 25 ohm resistor functions both as a fuse (in case of extreme overload) and partly a current limiter, e.g., when the capacit
- /archives//html/Amps/2010-02/msg00190.html (8,627 bytes)
- 7. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Gary Schafer" <garyschafer@comcast.net>
- Date: Sun, 7 Feb 2010 12:46:18 -0500
- I have seen a few older commercial amps with a resistor on the transformer side of the filter capacitors. I have also seen it in older handbook power supply projects. I haven't seen that done on anyt
- /archives//html/Amps/2010-02/msg00192.html (15,629 bytes)
- 8. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Carl" <km1h@jeremy.mv.com>
- Date: Sun, 7 Feb 2010 12:58:05 -0500
- Jim, Drake and Dentron both use a similar tiny resistor acting as a fuse. I guess they were trying to save money. The purpose of a properly sized HV resistor is to both limit a tubes fault current du
- /archives//html/Amps/2010-02/msg00193.html (10,395 bytes)
- 9. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: "Gary Schafer" <garyschafer@comcast.net>
- Date: Sun, 7 Feb 2010 13:22:50 -0500
- I agree with Carl. A fuse in the high voltage, whether it be a resistor or a regular fuse will sustain an arc when it opens and can let more energy thru than you want. The glitch resistor can not be
- /archives//html/Amps/2010-02/msg00196.html (11,820 bytes)
- 10. Re: [Amps] Vac Relays for B+ (score: 1)
- Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
- Date: Sun, 7 Feb 2010 18:44:51 +0000
- A genuine purpose-designed HV fuses don't look anything like a small resistor. That should be telling us something... Yes - and Jim VE7RF had it right too: INTERRUPTS the current ! That's right: two
- /archives//html/Amps/2010-02/msg00197.html (9,426 bytes)
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