20070301.ba v04_n023.bam.20070301 >From ???@??? Thu Mar 1 15:44:24 2007 -0600 Date: Thu, 1 Mar 2007 21:43:31 GMT From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4023 Message-Id: <20070301214332.B8B2C3183C1@srvr1.theporch.com> BOATANCHORS Digest 4023 Topics covered in this issue include: 1) Re: Lowering power supply output voltage. by W7QHO@aol.com 2) EMAIL ADDRESS UPDATE by "WA3GIN in Alex. City, VA" 3) Re: Lowering power supply output voltage. by Jack Antonio 4) Re: Lowering power supply output voltage. by "Arden Allen" 5) Re: Lowering power supply output voltage. by W7QHO@aol.com 6) New Drapes by Robert Nickels 7) Re: Lowering power supply output voltage. by "Brian A Clarke" 8) Re: Lowering power supply output voltage. by "Brian A Clarke" 9) Re: New Drapes by Tom Norris 10) Re: Lowering power supply output voltage. by "Morris Odell" 11) Re: New Drapes by Dan Arney 12) Re: New Drapes by "Tom Rauch" 13) Re: Lowering power supply output voltage. by "Tom Rauch" 14) Re: Lowering power supply output voltage. by "Morris Odell" 15) USA amateur call sign - overseas by John Sehring 16) Re: Lowering power supply output voltage. by W7QHO@aol.com 17) Re: Lowering power supply output voltage. by "Arden Allen" 18) Re: Lowering power supply output voltage. by "Arden Allen" 19) Re: Lowering power supply output voltage. by "Arden Allen" 20) Re: Lowering power supply output voltage. by Zengmeiste@aol.com ---------------------------------------------------------------------- From: W7QHO@aol.com Message-ID: Date: Wed, 28 Feb 2007 19:50:18 EST Subject: Re: Lowering power supply output voltage. To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_cc2.aad162b.33177d4a_boundary" --part1_cc2.aad162b.33177d4a_boundary Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable In a message dated 2/28/07 10:36:20 AM, gumbear@pacbell.net writes: > To keep the hacking to a minimum the simplest effectve way to lower the B+ > is to buck the B+ secondary winding with a small transformer driving a > silicon bridge rectifier.=A0 Insert the bridge output in series with the B= + > winding center tap, and the job is done.=A0 Use one of the multi-tapped > control transformers to come up with the right bucking voltage. >=20 > If the reciever has a filter choke converting to a choke input filter is a > good way to start the modification.=A0 Just move the input filter cap to t= he > other end of the choke.=A0 Then add the bucking voltage to the center tap. >=20 How about just using the multi-tap transformer to buck down the AC from one=20 half of the original HV secondary winding and bridge rectify that? Current= =20 drain by the receiver would be much reduced at the lower B+ voltage so no=20 problems with the original power transformer secondary winding. Dennis D. W7QHO Glendale, CA ************************************** AOL now offers free email to everyone.=20 Find out more about what's free from AOL at http://www.aol.com. --part1_cc2.aad162b.33177d4a_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_cc2.aad162b.33177d4a_boundary-- ------------------------------ From: "WA3GIN in Alex. City, VA" To: Old Tube Radios Subject: EMAIL ADDRESS UPDATE Date: Wed, 28 Feb 2007 20:18:17 -0500 Message-ID: <005301c75b9f$8d7c26c0$6301a8c0@TS480WA3GIN> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0054_01C75B75.A4A61EC0" This is a multi-part message in MIME format. ------=_NextPart_000_0054_01C75B75.A4A61EC0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 73, dave wa3gin@COMCAST.NET This is a new email address. The EROLS ACCOUNT will be terminated at the end of March. Please update your address book ;-) ------=_NextPart_000_0054_01C75B75.A4A61EC0 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 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ------=_NextPart_000_0054_01C75B75.A4A61EC0-- ------------------------------ Message-ID: <45E6319B.7000504@sbcglobal.net> Date: Wed, 28 Feb 2007 17:51:23 -0800 From: Jack Antonio MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: Lowering power supply output voltage. Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Couple of ideas 1. (Dangerous unless done right) Put in a 117Z3 or equivalent tube and half wave rectify the incoming AC line. But you'll need an isolation transformer, or seriously watch the grounding. 2.Here is an idea I saw once for obtaining a few milliamps for a bias supply, from an existing conventional B+ supply. The bias rectifier was fed from one of the high voltage windings through a capacitor. The capacitor value chosen to give the desired output voltage. A 1 uf cap has about 2600 ohms reactance at 60 cycle, what would happen if a a capacitor around that value were placed in series with each plate of the rectifier tube? Note, I've never tried this, just throwing it out for experimentation or comments. Jack Jack Antonio WA7DIA scr287@sbcglobal.net David Stinson wrote: > OK; we've heard a basket of "it won't work." > > Here's the deal: > I have a BA receiver with standard +250 VDC B+, > full-wave rect. center tap grounded, > pi-type cap input/output filter, > 5 and 6 volt AC for fils > just like a bi-zillion radios out there. > I want to run the B+ at 100 volts, not 250. > I will change nothing whatsoever in the receiver except > the power supply, having run it on 100 volts external > for many hours and been satisfied with its performance. > > What's the "right" way to do it? > And "leave it alone and run 250 volts" is not an answer. > It's 100 volts if I have to do it with batteries. > > So, all you smarty-pants engineer types ;-), > > Get'er Done! > > ------------------------------ Message-ID: <002101c75ba9$86527520$39e47443@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Wed, 28 Feb 2007 18:27:49 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > How about just using the multi-tap transformer to buck down the AC from one half of the original HV secondary winding and bridge rectify that? Current drain by the receiver would be much reduced at the lower B+ voltage so no problems with the original power transformer secondary winding. ... My thought was the advantage to bucking the center tap is a minimum of rewiring and also the bucking transformer winding is not elevated so much above ground. Arden Allen KB6NAX ------------------------------ From: W7QHO@aol.com Message-ID: Date: Wed, 28 Feb 2007 23:54:50 EST Subject: Re: Lowering power supply output voltage. To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_c3b.f170083.3317b69a_boundary" --part1_c3b.f170083.3317b69a_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 2/28/07 6:31:52 PM, gumbear@pacbell.net writes: > My thought was the advantage to bucking the center tap is a minimum of > rewiring > Trivial rewiring job in either case. > and also the bucking transformer winding is not elevated so much > above ground. > Uhhh,,,yes, but not likely to be a problem at receiver PS voltages. Anyway Dave, are you going to use any of this stuff or are you playing games here? Dennis D. W7QHO Glendale, CA ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com. --part1_c3b.f170083.3317b69a_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_c3b.f170083.3317b69a_boundary-- ------------------------------ Message-ID: <45E65EBD.9030702@oneradio.net> Date: Wed, 28 Feb 2007 23:03:57 -0600 From: Robert Nickels MIME-Version: 1.0 To: Old Tube Radios Subject: New Drapes Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit As a service to anyone thinking of bidding, the red drapes appear to have been replaced by something from the Martha Stewart collection: http://search.ebay.com/_W0QQsassZradio-martQQhtZ-1 Pass the word... 73, Bob W9RAN ------------------------------ Message-ID: <01a501c75bc5$7a701840$0202a8c0@Belkin> From: "Brian A Clarke" To: Old Tube Radios Cc: "Old Tube Radios" Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 16:50:10 +1100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Can we please leave half-wave rectification out of mains powered sets? It feeds DC into your transformer and back into the mains. As if we don't get enough rubbish on the mains from those who push SMPSUs. 73 de Brian, Vk2GCE. ----- Original Message ----- From: "Jack Antonio" > Couple of ideas > > 1. (Dangerous unless done right) Put in a 117Z3 or > equivalent tube and half wave rectify the incoming AC line. > But you'll need an isolation transformer, or seriously watch > the grounding. ------------------------------ Message-ID: <01ad01c75bc5$c8173ec0$0202a8c0@Belkin> From: "Brian A Clarke" To: Old Tube Radios Cc: "Old Tube Radios" Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 16:52:21 +1100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Very dangerous in three-wire mains systems. Brian. ----- Original Message ----- From: "Arden Allen" To: "Old Tube Radios" <> Sent: Thursday, March 01, 2007 1:27 PM Subject: Re: Lowering power supply output voltage. > > How about just using the multi-tap transformer to buck down the AC from > one > half of the original HV secondary winding and bridge rectify that? Current > drain by the receiver would be much reduced at the lower B+ voltage so no > problems with the original power transformer secondary winding. ... > > My thought was the advantage to bucking the center tap is a minimum of > rewiring and also the bucking transformer winding is not elevated so much > above ground. > > Arden Allen > KB6NAX > ------------------------------ Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <930CDA28-D95F-4B8F-8F96-002C9E0D9B8F@bellsouth.net> Content-Transfer-Encoding: 7bit From: Tom Norris Subject: Re: New Drapes Date: Thu, 1 Mar 2007 00:16:06 -0600 To: Old Tube Radios hahahahaha Radio Mart does it again! 73 Tom NU4G On Feb 28, 2007, at 11:03 PM, Robert Nickels wrote: > As a service to anyone thinking of bidding, the red drapes appear > to have been replaced by something from the Martha Stewart collection: > > http://search.ebay.com/_W0QQsassZradio-martQQhtZ-1 > > Pass the word... > > 73, Bob W9RAN > ------------------------------ Message-ID: <002601c75bd8$70f2c390$ad00a8c0@Morris1> From: "Morris Odell" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 19:05:56 +1100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit Hi all, > 2.Here is an idea I saw once for obtaining > a few milliamps for a bias supply, from an existing > conventional B+ supply. The bias rectifier was fed from one > of the high voltage windings through a capacitor. The capacitor > value chosen to give the desired output voltage. > > A 1 uf cap has about 2600 ohms reactance at 60 cycle, what would happen > if a a capacitor around that value were placed in series with each plate > of the rectifier tube? Please gents, doesn't anyone remember any rectifier theory? A capacitor in series with the usual rectifier plate will not do anything useful at all. It's important to remember that although we are dealing with an AC transformer here, all the currents in the leads to the common full wave centre tapped secondary winding are carrying DC!!!! That goes for each plate connection and the cantre tap too. If you put capacitors in series with the plates all you do is block the DC and there will be no output from the diode cathodes. If you put a transformer secondary winding in series with the CT you are not bucking anything but injecting AC in series with the rectifier output at half the ripple frequency. The common diode bias circuit with a cap from one side of a centre tapped winding is probably a half wave doubler where you can control the output voltage by using an appropriate sized input cap which limits the charge extracted per cycle, but that's nothing like a full wave rectifier cct and another story altogether. OTOH if you are using a full wave 4 diode bridge with a non tapped secondary, the transformer winding is carrying AC and you could put a cap in series with it to introduce reactance. That might be the solution to Dave's original query. Use a Si diode bridge across half the secondary with a suitably rated cap in series. Carry on, Morris VK3DOC ------------------------------ Message-ID: <45E68275.2040207@pacbell.net> Date: Thu, 01 Mar 2007 01:36:21 -0600 From: Dan Arney MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: New Drapes Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Bob, I had to go get my old frogging chest waders on to read his BS on the KWM-2A he has listed. I nearly drowned in his BS. The pictures look like Collins sales pictures. What a crock. Has no ham call???????? Hank KN6DI/5 ------------------------------ Message-ID: <00ef01c75bea$e79401a0$640fa8c0@radioroom> From: "Tom Rauch" To: Old Tube Radios Subject: Re: New Drapes Date: Thu, 1 Mar 2007 05:17:36 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit > As a service to anyone thinking of bidding, the red drapes > appear to have been replaced by something from the Martha > Stewart collection: If you look at this link: http://apps.sos.ky.gov/business/obdb/(giwmi3udjnilhk24hny2yg2w)/showentity.aspx?id=0510329&ct=09&cs=99999 you will see that company is a corporation in bad standing with Ky. A friend of mine in north Georgia sold a Drake receiver of only modest appearance and it appeared on e place as part of a "my personal collection absolutely mint almost never used" when offered for re-sale. ------------------------------ Message-ID: <00f601c75bec$8d3e5370$640fa8c0@radioroom> From: "Tom Rauch" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 05:29:45 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit > the diode cathodes. If you put a transformer secondary > winding in series with the CT you are not bucking anything > but injecting AC in series with the rectifier output at > half the ripple frequency. With an AC winding you actually unbalance the voltage at the rectifier anodes, making it like a sorta half-wave sorta fullwave. I like to think of it as a dysfunctional full wave. If you inject negative filtered negative voltage from a small supply to the center tap, then you reduce voltage by exploding the filter capacitor you connected to the center tap. If the capacitor does not explode then it will charge to what used to be full high voltage but negative, and then the B+ will be zero. You could stop the explosion of capacitor by adding a large resistor that, no surprise, would now dissipate more power than a resistor at the rectifier cathode or by itself would do. Why does that happen? Because the CT of the transformer is a NEGATIVE unfiltered voltage source. It is NOT a negative voltage sink, it is a SOURCE. I'm learning a lot about what to do to make a simple system complicated while not really solving any problem. Poor old radios. They used to be so happy before they were subjected to a lobotomy. 73 Tom ------------------------------ Message-ID: <001201c75bf4$5255a1c0$ad00a8c0@Morris1> From: "Morris Odell" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 22:25:31 +1100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit >> the diode cathodes. If you put a transformer secondary winding in series >> with the CT you are not bucking anything but injecting AC in series with >> the rectifier output at half the ripple frequency. > > With an AC winding you actually unbalance the voltage at the rectifier > anodes, making it like a sorta half-wave sorta fullwave. I like to think > of it as a dysfunctional full wave. If you do it at RF frequencies and there's no filter cap, it's a balanced mixer :-) Morris ------------------------------ Content-Disposition: inline Content-Transfer-Encoding: binary Mime-Version: 1.0 From: John Sehring To: Old Tube Radios Subject: USA amateur call sign - overseas Content-Type: text/plain Message-Id: <20070301180103.220A6237C25@filter6.e-filtering.net> Date: Thu, 1 Mar 2007 11:01:03 -0700 (MST) I will be living up here in Canada for a long time. Been wondering about my US amateur radio license... Need to tell the FCC my new mailing address in Canada? Do any of you think that this will cause any problems? I've searched the FCC's web site but no luck. This bi-national living sometimes drives me nuts! Administrative snafus galore & many comlexities. --John Sehring WB0EQ/VE6 ------------------------------ From: W7QHO@aol.com Message-ID: Date: Thu, 1 Mar 2007 13:28:56 EST Subject: Re: Lowering power supply output voltage. To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_cc8.bc1c95b.33187568_boundary" --part1_cc8.bc1c95b.33187568_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 3/1/07 12:08:05 AM, vilgotch@bigpond.net.au writes: > OTOH if you are using a full wave 4 diode bridge with a non tapped > secondary, the transformer winding is carrying AC and you could put a cap in > series with it to introduce reactance. That might be the solution to Dave's > original query. Use a Si diode bridge across half the secondary with a > suitably rated cap in series. > Hmmm...novel and interesting. Probably better to bridge only half of the secondary to keep voltages down. Regulation would be a very poor. Dennis D. W7QHO Glendale, CA ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com. --part1_cc8.bc1c95b.33187568_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_cc8.bc1c95b.33187568_boundary-- ------------------------------ Message-ID: <006101c75c3a$76f0f570$33e47443@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 11:42:02 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit I know it is antiquated technology but maybe it will be received by a few here. It consists of using a pencil and paper to sketch a schematic diagram of the proposed power supply modification. Add little arrows along side the conductors to indicate the direction of current flow. Decide whether to use electron flow direction or classical current flow direction - one is the opposite of the other. Now think of the <<<>>> as utilizing both half cycles of a rectified transformer secondary with the current from both half cycles flowing in the same direction. Feeding this pulsating current into the center tap of the receiver tube rectifier's B+ transormer winding will either add voltage or subtract voltage from the cathode of the reciever's tube rectifier, depending on which way one has decided that current flows. Does anyone understand now? Kudos to Morris for explaining that DC does now get to flow through capacitors ;-) Arden Allen KB6NAX ------------------------------ Message-ID: <006001c75c3a$766a6050$33e47443@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 11:40:33 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > They used to be so happy before they were subjected to a lobotomy. Fret not, help is on the way.... Arden Allen KB6NAX ------------------------------ Message-ID: <006201c75c3a$7792dac0$33e47443@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Lowering power supply output voltage. Date: Thu, 1 Mar 2007 11:45:57 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > If you do it at RF frequencies and there's no filter cap, it's a balanced > mixer :-) Seems it's easy enough to get mixed up at power line frequencies! )-: Arden Allen KB6NAX ------------------------------ From: Zengmeiste@aol.com Message-ID: Date: Thu, 1 Mar 2007 16:42:55 EST Subject: Re: Lowering power supply output voltage. To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_d14.4edd7d3.3318a2df_boundary" --part1_d14.4edd7d3.3318a2df_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Would a low-tech (newbie) suggestion work?. I don't recall if anyone's proffered the idea of just using a rheostat somewhere (at the CT?) to tweak the B+? Those old Really big boatanchor AM transmitters used them to keep things copacetic, dint they? Awaiting feedback , 73, Terry KC9KEL


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AOL now offers free email to everyone. Find out more about what's free from AOL at --part1_d14.4edd7d3.3318a2df_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_d14.4edd7d3.3318a2df_boundary-- ------------------------------ End of BOATANCHORS Digest 4023 ******************************