20100808.ba v04_n345.bam.20100808 >From ???@??? Sun Aug 8 10:21:08 2010 -0500 Date: Sun, 8 Aug 2010 10:21:04 CST From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4345 Message-Id: <20100808162104.CEC13D58B94@minime.theporch.com> BOATANCHORS Digest 4345 Topics covered in this issue include: 1) Attention Smart People: by 2) RE: Attention Smart People: by "Jim Garland" <4cx250b@muohio.edu> 3) RE: Attention Smart People: by "Bill Hawkins" 4) Re: Attention Smart People: by WA5CAB@cs.com 5) Re: Attention Smart People: by mac 6) RE: Attention Smart People: by "Bill Hawkins" 7) Re: Attention Smart People: by mac 8) Re: Attention Smart People: by "Arden Allen" 9) RE: Attention Smart People: by "Morris Odell" 10) Re: Attention Smart People: by 11) Re: Attention Smart People: by Roy Morgan 12) Re: Attention Smart People: by "Arden Allen" 13) Re: Attention Smart People: by "Don Davis" 14) Re: Attention Smart People: by mac 15) NC-270 manual question by Mike Steussy 16) Miller Chokes by "Bob Kemp" ---------------------------------------------------------------------- Message-ID: <727555E76B4A46308DDE3B391735F23A@boudreaux> From: To: Old Tube Radios Subject: Attention Smart People: Date: Tue, 3 Aug 2010 08:03:46 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit Please take a look at this full-wave doubler circuit: http://www.kwarc.org/bulletin/99-04/tech_corner.htm At the end of the page is this warning: This circuit can be operated off the AC line 120 or 230 V). BUT the negative ground must be left floating since one side of the line Is grounded and YOU CANNOT ground both the Input and the NEG (or POS) DC or else B O O M! I guess I'm stupid (I've only had one cup of coffee, so there's my excuse), because I don't see a current path from the DC B+ side to the AC line, other than ground which is supposed to be -0- potential on both sides. Now, if your B- ground came loose on the power supply and you didn't have a grounded line cord installed (which would be even stupider than me with this kind of voltage) you'd have full B- on the chassis to ground and your wife would have to pay for a funeral. OK... what am I missing here? ------------------------------ From: "Jim Garland" <4cx250b@muohio.edu> To: Old Tube Radios Subject: RE: Attention Smart People: Date: Tue, 3 Aug 2010 08:38:50 -0600 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Yes, I believe the circuit will go "boom" if run directly off the AC line and the negative output is grounded, at least for a 120V line. When connected directly to the AC line, the "L" wire replaces the top side of the transformer secondary, and the "N" wire replaces the bottom side of the transformer secondary. Since N is usually only a volt or two away from G on a 120V circuit, grounding the negative output will short out half the power supply. It is more interesting to consider what happens if the transformerless supply is connected to a 240V circuit, with L1 and L2 replacing the xfmr secondary and N connected to Ground. In this case, the circuit is symmetrical about ground and very well might work. I'd feel uneasy about doing it, but I don't see any problems. 73, Jim W8ZR > -----Original Message----- > From: owner-boatanchors@theporch.com [mailto:owner-boatanchors@theporch.com] On > Behalf Of arc5@ix.netcom.com > Sent: Tuesday, August 03, 2010 7:04 AM > To: Old Tube Radios > Subject: Attention Smart People: > > Please take a look at this full-wave doubler circuit: > > http://www.kwarc.org/bulletin/99-04/tech_corner.htm > > At the end of the page is this warning: > > This circuit can be operated off the AC line 120 or 230 V). > BUT the negative ground must be left floating since > one side of the line Is grounded and YOU CANNOT ground > both the Input and the NEG (or POS) DC or else B O O M! > > I guess I'm stupid (I've only had one cup of coffee, so there's my excuse), > because I don't see a current path from the DC B+ side > to the AC line, other than ground which is supposed to be -0- potential > on both sides. Now, if your B- ground came loose on the power supply > and you didn't have a grounded line cord installed > (which would be even stupider than me with this kind of voltage) > you'd have full B- on the chassis to ground and your wife > would have to pay for a funeral. > > OK... what am I missing here? ------------------------------ From: "Bill Hawkins" To: Old Tube Radios Subject: RE: Attention Smart People: Date: Tue, 3 Aug 2010 10:19:44 -0500 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Well, for grounded 240 volt, you wouldn't want to lose one side of it. Use twin breakers, not fuses. Bill Hawkins -----Original Message----- From: owner-boatanchors@theporch.com [mailto:owner-boatanchors@theporch.com] On Behalf Of Jim Garland Sent: Tuesday, August 03, 2010 9:39 AM To: Old Tube Radios Subject: RE: Attention Smart People: Yes, I believe the circuit will go "boom" if run directly off the AC line and the negative output is grounded, at least for a 120V line. When connected directly to the AC line, the "L" wire replaces the top side of the transformer secondary, and the "N" wire replaces the bottom side of the transformer secondary. Since N is usually only a volt or two away from G on a 120V circuit, grounding the negative output will short out half the power supply. It is more interesting to consider what happens if the transformerless supply is connected to a 240V circuit, with L1 and L2 replacing the xfmr secondary and N connected to Ground. In this case, the circuit is symmetrical about ground and very well might work. I'd feel uneasy about doing it, but I don't see any problems. 73, Jim W8ZR > -----Original Message----- > From: owner-boatanchors@theporch.com [mailto:owner-boatanchors@theporch.com] On > Behalf Of arc5@ix.netcom.com > Sent: Tuesday, August 03, 2010 7:04 AM > To: Old Tube Radios > Subject: Attention Smart People: > > Please take a look at this full-wave doubler circuit: > > http://www.kwarc.org/bulletin/99-04/tech_corner.htm > > At the end of the page is this warning: > > This circuit can be operated off the AC line 120 or 230 V). > BUT the negative ground must be left floating since > one side of the line Is grounded and YOU CANNOT ground > both the Input and the NEG (or POS) DC or else B O O M! > > I guess I'm stupid (I've only had one cup of coffee, so there's my excuse), > because I don't see a current path from the DC B+ side > to the AC line, other than ground which is supposed to be -0- potential > on both sides. Now, if your B- ground came loose on the power supply > and you didn't have a grounded line cord installed > (which would be even stupider than me with this kind of voltage) > you'd have full B- on the chassis to ground and your wife > would have to pay for a funeral. > > OK... what am I missing here? ------------------------------ From: WA5CAB@cs.com Message-ID: <28058.2ab18869.39899297@cs.com> Date: Tue, 3 Aug 2010 11:41:11 EDT Subject: Re: Attention Smart People: To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_28058.2ab18869.39899297_boundary" --part1_28058.2ab18869.39899297_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Dave (and Jim), Mentally erase all of the components except for the transformer secondary and the two input diodes with anodes connected to the ground symbol. If the transformer secondary is one-half of the pole-pig 120/240 secondary, then call the bottom of the secondary N (typical US practive). So N is "actually" grounded. The top is thus L1 (or could also be L2). When L1 is instantaneously positive, N is instantaneously negative and the ground symbol is one PN drop above ground. Not particularly dangerous. But when L1 goes negative, N goes positive and the ground symbol tracks the instantaneous voltage on L1, going down to a negative peak of about 170 volts (less the PN drop). If the two transformer leads are L1 and L2, then the ground symbol varies between +/- 170 V relative to the not-shown N. So the difference in what happens between connecting the circuit to 120 or 240 and tying the ground symbol to N is BOOM and BIGGER BOOM. On the other hand, using the circuit with an isolated transformer as originally intended is no more dangerous than a bridge rectifier circuit producing the same output voltage, except that there are several more points not to touch. In a message dated 8/3/2010 9:59:18 AM Central Daylight Time, 4cx250b@muohio.edu writes: > Yes, I believe the circuit will go "boom" if run directly off the AC > line > and the negative output is grounded, at least for a 120V line. When > connected directly to the AC line, the "L" wire replaces the top side of > the > transformer secondary, and the "N" wire replaces the bottom side of the > transformer secondary. Since N is usually only a volt or two away from G > on > a 120V circuit, grounding the negative output will short out half the > power > supply. > > It is more interesting to consider what happens if the transformerless > supply is connected to a 240V circuit, with L1 and L2 replacing the xfmr > secondary and N connected to Ground. In this case, the circuit is > symmetrical about ground and very well might work. I'd feel uneasy about > doing it, but I don't see any problems. > 73, > Jim W8ZR > > >-----Original Message----- > >From: owner-boatanchors@theporch.com > [mailto:owner-boatanchors@theporch.com] On > >Behalf Of arc5@ix.netcom.com > >Sent: Tuesday, August 03, 2010 7:04 AM > >To: Old Tube Radios > >Subject: Attention Smart People: > > > >Please take a look at this full-wave doubler circuit: > > > >http://www.kwarc.org/bulletin/99-04/tech_corner.htm > > > >At the end of the page is this warning: > > > > This circuit can be operated off the AC line 120 or 230 V). > > BUT the negative ground must be left floating since > > one side of the line Is grounded and YOU CANNOT ground > > both the Input and the NEG (or POS) DC or else B O O M! > > > >I guess I'm stupid (I've only had one cup of coffee, so there's my > excuse), > >because I don't see a current path from the DC B+ side > >to the AC line, other than ground which is supposed to be -0- potential > >on both sides. Now, if your B- ground came loose on the power supply > >and you didn't have a grounded line cord installed > >(which would be even stupider than me with this kind of voltage) > >you'd have full B- on the chassis to ground and your wife > >would have to pay for a funeral. > > > >OK... what am I missing here? > Robert & Susan Downs - Houston wa5cab dot com (Web Store) MVPA 9480 --part1_28058.2ab18869.39899297_boundary Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * --part1_28058.2ab18869.39899297_boundary-- ------------------------------ From: mac To: Old Tube Radios Subject: Re: Attention Smart People: Message-Id: <55C2D15C-2419-45B6-80D5-73A63F748360@aol.com> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v936) Date: Tue, 3 Aug 2010 11:14:52 -0700 Cc: Old Tube Radios The author is incorrect, the "standard" 2-diode, 2-cap circuit as shown in the ARRL (and other) references does put out a 120, NOT a 60 cps ripple. Don't see where this circuit does anything the simpler circuit doesn't do and with 4 fewer diodes. Nor would it be more or less hazardous when operating directly off an AC line. More points to touch, though, as Robert points out. :^) Dennis D. W7QHO Glendale, CA ************** On Aug 3, 2010, at 6:03 AM, wrote: > Please take a look at this full-wave doubler circuit: > > http://www.kwarc.org/bulletin/99-04/tech_corner.htm > > At the end of the page is this warning: > > This circuit can be operated off the AC line 120 or 230 V). BUT > the negative ground must be left floating since one side of the > line Is grounded and YOU CANNOT ground both the Input and the NEG > (or POS) DC or else B O O M! > I guess I'm stupid (I've only had one cup of coffee, so there's my > excuse), > because I don't see a current path from the DC B+ side to the AC > line, other than ground which is supposed to be -0- potential on > both sides. Now, if your B- ground came loose on the power supply > and you didn't have a grounded line cord installed (which would be > even stupider than me with this kind of voltage) you'd have full B- > on the chassis to ground and your wife would have to pay for a > funeral. > > OK... what am I missing here? > ------------------------------ From: "Bill Hawkins" To: Old Tube Radios Subject: RE: Attention Smart People: Date: Tue, 3 Aug 2010 14:29:41 -0500 Message-ID: <66B01205000543159020B36AA3F82489@cyrus> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Well, it pays to look at the circuit. It will not work with a center-tapped transformer like a 120-0-120 pole pig. The two diodes shown grounded at one end will go 'boom'. So twin breakers are not necessary. The transformer winding must be isolated so that either end can be at full voltage above ground. One secondary fuse will be enough. But no, the author is correct - 2 diodes and 2 caps does have 60 Hz ripple. On one half cycle, the doubling cap charges to the secondary peak voltage while the output cap continues to discharge. On the next half cycle, the doubling cap minus end is raised to secondary voltage and the + end charges the output cap, once per full cycle. Going to 120 Hz ripple could divide the output cap value by 2, which could pay for the extra cap and 4 diodes. Bill Hawkins -----Original Message----- From: owner-boatanchors@theporch.com [mailto:owner-boatanchors@theporch.com] On Behalf Of mac Sent: Tuesday, August 03, 2010 1:15 PM To: Old Tube Radios Cc: Old Tube Radios Subject: Re: Attention Smart People: The author is incorrect, the "standard" 2-diode, 2-cap circuit as shown in the ARRL (and other) references does put out a 120, NOT a 60 cps ripple. Don't see where this circuit does anything the simpler circuit doesn't do and with 4 fewer diodes. Nor would it be more or less hazardous when operating directly off an AC line. More points to touch, though, as Robert points out. :^) Dennis D. W7QHO Glendale, CA ************** On Aug 3, 2010, at 6:03 AM, wrote: > Please take a look at this full-wave doubler circuit: > > http://www.kwarc.org/bulletin/99-04/tech_corner.htm > > At the end of the page is this warning: > > This circuit can be operated off the AC line 120 or 230 V). BUT > the negative ground must be left floating since one side of the > line Is grounded and YOU CANNOT ground both the Input and the NEG > (or POS) DC or else B O O M! > I guess I'm stupid (I've only had one cup of coffee, so there's my > excuse), > because I don't see a current path from the DC B+ side to the AC > line, other than ground which is supposed to be -0- potential on > both sides. Now, if your B- ground came loose on the power supply > and you didn't have a grounded line cord installed (which would be > even stupider than me with this kind of voltage) you'd have full B- > on the chassis to ground and your wife would have to pay for a > funeral. > > OK... what am I missing here? > ------------------------------ Cc: Old Tube Radios Message-Id: <1DE15CCD-34BB-48E4-BF44-822ECB8FBF74@aol.com> From: mac To: Old Tube Radios Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v936) Subject: Re: Attention Smart People: Date: Tue, 3 Aug 2010 13:50:57 -0700 Bill, No, the 2-diode, 2-cap circuit (page 316, 1968 ARRL Handbook for ex.) does have a 120 cycle OUTPUT ripple. In the circuit two caps are connected in series across the output (load). On any given half cycle of the input AC, the peak output voltage is the sum of the peak incoming AC (which is also charging one cap) and the peak voltage to which the other cap was charged on the previous half cycle. On the next half-cycle the "roles" roles of the two capacitors are reversed, i.e, the first cap now provides the voltage peak to be added to the input voltage to get the 2 X doubling action and the "second" cap (see above) will be receiving it's new charge. THE TWO DIODES AND THE CIRCUIT SPECIFICS SERVE TO KEEP THE POLARITIES CORRECT TO ACCOMPLISH ALL THIS. Thus there will be a 2 X(1.4 +1.4)rms output peak EVERY half cycle or 120/sec for a 60 Hz input frequency. To use your terminology, the "doubling" and "output" caps switch jobs each half- cycle. Rather elegant little circuit actually....... Dennis D. W7QHO Glendale, CA On Aug 3, 2010, at 12:29 PM, Bill Hawkins wrote: > But no, the author is correct - 2 diodes and 2 caps does > have 60 Hz ripple. On one half cycle, the doubling cap > charges to the secondary peak voltage while the output > cap continues to discharge. On the next half cycle, the > doubling cap minus end is raised to secondary voltage and > the + end charges the output cap, once per full cycle. ------------------------------ Message-ID: <002901cb335a$78e3a850$1d9f480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Attention Smart People: Date: Tue, 3 Aug 2010 15:23:12 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > The author is incorrect, the "standard" 2-diode, 2-cap circuit as shown in the ARRL (and other) references does put out a 120, NOT a 60 cps ripple. Don't see where this circuit does anything the simpler circuit doesn't do and with 4 fewer diodes. Nor would it be more or less hazardous when operating directly off an AC line. ...... Well, Dennis gets the big stuffed ham prize for detecting the obvious. The two diode two cap circuit is a full wave rectifier with 120Hz ripple. Goes to show how simplicity is suspect in the minds of those who like a good challenge ;-) Arden Allen KB6NAX Properly trained a man can be dog's best friend. -Corey Ford ------------------------------ From: "Morris Odell" To: Old Tube Radios Subject: RE: Attention Smart People: Date: Wed, 4 Aug 2010 07:15:16 +1000 Message-ID: <000001cb3350$f86db250$e94916f0$@bigpond.net.au> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Content-Language: en-au It wouldn't take much to lash both circuits up on the bench to see what's really going on. I'm rather busy until next week but if anyone else feels like doing it please post the results. I'd use a little filament trans, diodes, caps and a load resistor from the JB. 73, Morris -----Original Message----- From: owner-boatanchors@theporch.com [mailto:owner-boatanchors@theporch.com] On Behalf Of mac Sent: Wednesday, 4 August 2010 6:51 AM To: Old Tube Radios Cc: Old Tube Radios Subject: Re: Attention Smart People: Bill, No, the 2-diode, 2-cap circuit (page 316, 1968 ARRL Handbook for ex.) does have a 120 cycle OUTPUT ripple. In the circuit two caps are connected in series across the output (load). On any given half cycle of the input AC, the peak output voltage is the sum of the peak incoming AC (which is also charging one cap) and the peak voltage to which the other cap was charged on the previous half cycle. On the next half-cycle the "roles" roles of the two capacitors are reversed, i.e, the first cap now provides the voltage peak to be added to the input voltage to get the 2 X doubling action and the "second" cap (see above) will be receiving it's new charge. THE TWO DIODES AND THE CIRCUIT SPECIFICS SERVE TO KEEP THE POLARITIES CORRECT TO ACCOMPLISH ALL THIS. Thus there will be a 2 X(1.4 +1.4)rms output peak EVERY half cycle or 120/sec for a 60 Hz input frequency. To use your terminology, the "doubling" and "output" caps switch jobs each half- cycle. Rather elegant little circuit actually....... Dennis D. W7QHO Glendale, CA On Aug 3, 2010, at 12:29 PM, Bill Hawkins wrote: > But no, the author is correct - 2 diodes and 2 caps does have 60 Hz > ripple. On one half cycle, the doubling cap charges to the secondary > peak voltage while the output cap continues to discharge. On the next > half cycle, the doubling cap minus end is raised to secondary voltage > and the + end charges the output cap, once per full cycle. ------------------------------ Message-ID: From: To: Old Tube Radios Subject: Re: Attention Smart People: Date: Tue, 3 Aug 2010 22:34:39 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit DUH! I didn't understand when he said "off the AC-line" that he meant transformerless.... See what happens when I try to think without coffee? ------------------------------ Message-Id: From: Roy Morgan To: Old Tube Radios Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v936) Subject: Re: Attention Smart People: Date: Wed, 4 Aug 2010 01:13:45 -0400 On Aug 3, 2010, at 3:29 PM, Bill Hawkins wrote: > Well, it pays to look at the circuit. Yes. I found it interesting to look at the explanation, which includes a rant against the ARRL: > "... they have never changed their terminology. I think this is due > to the fact that much of their theory was taken from Terman or > Ghirardhi and they didn't want to offend these pundits. " It seems to me that both Terman (d. 1982) and Ghirardhi are now "silent keys". It's not clear how they could be offended by the ARRL, even in 1980. Roy Roy Morgan k1lky@earthlink.net K1LKY Since 1958 - Keep 'em Glowing! ------------------------------ Message-ID: <002101cb339b$98e80100$959d480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Attention Smart People: Date: Tue, 3 Aug 2010 23:09:23 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit BTW, I forgot to mention, the two diode two cap circuit IS a voltage doubling full wave rectifier circuit. Diode 1 charges cap on one half cycle, Diode 2 adds the other half cycle charge to the cap. Voila! Peak voltage plus peak voltage = doublemint juice for your rig. Albert Einstein said it best, "Things should be made as simple as possible but not simpler." ----- Original Message ----- From: Arden Allen To: Old Tube Radios Sent: Tuesday, August 03, 2010 3:23 PM Subject: Re: Attention Smart People: > The author is incorrect, the "standard" 2-diode, 2-cap circuit as shown in the ARRL (and other) references does put out a 120, NOT a 60 cps ripple. Don't see where this circuit does anything the simpler circuit doesn't do and with 4 fewer diodes. Nor would it be more or less hazardous when operating directly off an AC line. ...... Well, Dennis gets the big stuffed ham prize for detecting the obvious. The two diode two cap circuit is a full wave rectifier with 120Hz ripple. Goes to show how simplicity is suspect in the minds of those who like a good challenge ;-) Arden Allen KB6NAX Properly trained a man can be dog's best friend. -Corey Ford ------------------------------ Message-ID: From: "Don Davis" To: Old Tube Radios Cc: "Old Tube Radios" Subject: Re: Attention Smart People: Date: Tue, 3 Aug 2010 23:30:47 -0700 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit When operating off of 120 vac one input to the doubler circuit is at ground. If you put one of the doubler out puts to ground also, then one of the input diodes will be shorted out. This will place the opposite diode directly across 120 vac input which will fry the diode in a few msec. BOOM. 73 de don ad6pb ----- Original Message ----- From: "mac" To: "Old Tube Radios" Cc: "Old Tube Radios" Sent: Tuesday, August 03, 2010 11:14 AM Subject: Re: Attention Smart People: > The author is incorrect, the "standard" 2-diode, 2-cap circuit as > shown in the ARRL (and other) references does put out a 120, NOT a 60 > cps ripple. Don't see where this circuit does anything the simpler > circuit doesn't do and with 4 fewer diodes. Nor would it be more or > less hazardous when operating directly off an AC line. More points to > touch, though, as Robert points out. :^) > > Dennis D. W7QHO > Glendale, CA > > ************** > On Aug 3, 2010, at 6:03 AM, wrote: > >> Please take a look at this full-wave doubler circuit: >> >> http://www.kwarc.org/bulletin/99-04/tech_corner.htm >> >> At the end of the page is this warning: >> >> This circuit can be operated off the AC line 120 or 230 V). BUT >> the negative ground must be left floating since one side of the >> line Is grounded and YOU CANNOT ground both the Input and the NEG >> (or POS) DC or else B O O M! >> I guess I'm stupid (I've only had one cup of coffee, so there's my >> excuse), >> because I don't see a current path from the DC B+ side to the AC >> line, other than ground which is supposed to be -0- potential on >> both sides. Now, if your B- ground came loose on the power supply >> and you didn't have a grounded line cord installed (which would be >> even stupider than me with this kind of voltage) you'd have full B- >> on the chassis to ground and your wife would have to pay for a >> funeral. >> >> OK... what am I missing here? >> > > ------------------------------ From: mac To: Old Tube Radios Subject: Re: Attention Smart People: Message-Id: <9492306B-DF81-48DD-9097-02295C0F178C@aol.com> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v936) Date: Wed, 4 Aug 2010 12:01:22 -0700 Cc: "Old Tube Radios" Yep, the use of a floating ground buss on the output side would be required. One of the early SSB xcvrs did this using a voltage quadrupler off the AC line to provide HV for the linear PA. Dennis D. W7QHO Glendale, CA On Aug 3, 2010, at 11:30 PM, Don Davis wrote: > When operating off of 120 vac one input to the doubler circuit is at > ground. If you put one of the doubler out puts to ground also, then > one of the input diodes will be shorted out. This will place the > opposite diode directly across 120 vac input which will fry the > diode in a few msec. BOOM. ------------------------------ Message-ID: <4C5B7A5D.5060802@cox.net> Date: Thu, 05 Aug 2010 22:58:37 -0400 From: Mike Steussy MIME-Version: 1.0 To: Old Tube Radios Subject: NC-270 manual question Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Ahoy! Am I correct in assuming that page 2 of the National NC-270 manual is blank? A friend picked up a nice one at the Shenandoah Valley hamfest at Berryville last weekend and has been looking at manual sources on line. The hamfest was FB, larger than any previous one I can remember. 73, Mike Steussy AE4R Vienna VA ------------------------------ Message-ID: <593C36A76BCC42C8A40560F83D8A3D22@robert7549ca67> From: "Bob Kemp" To: Old Tube Radios Subject: Miller Chokes Date: Sun, 8 Aug 2010 11:14:12 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit Have some NOS Miller RF Chokes: #4646 .24millihenry/125ma units (7) in all. and (1) #4628E 39.0uh 65 ohms 300ma . Make offer. Bob wa0vrc ------------------------------ End of BOATANCHORS Digest 4345 ******************************