20100320.ba v04_n326.bam.20100320 >From ???@??? Sat Mar 20 09:39:44 2010 -0500 Date: Sat, 20 Mar 2010 09:39:39 CST From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4326 Message-Id: <20100320153940.734D05D164D@minime.theporch.com> BOATANCHORS Digest 4326 Topics covered in this issue include: 1) Re: 75A-4 Filter impedance by Al Klase 2) Meyer Gottesman re: 75A-4 for sale. by Meyer Gottesman 3) Re: 75A-4 Filter impedance by John Oglesby 4) Re: Recovering "Bumble Bee" Capacitors by "Arden Allen" 5) Re: Recovering "Bumble Bee" Capacitors by "Arden Allen" 6) UV202 question by "JAMES HANLON" 7) RE: UV202 question by "Singley, Rodger" 8) Re: 75A-4 Filter impedance by John Kolb 9) Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver by John Kolb 10) Re: 75A-4 Filter impedance by Scott Robinson 11) Re: 75A-4 Filter impedance by John Oglesby 12) Re: 75A-4 Filter impedance by spr@earthlink.net 13) Re: 75A-4 Filter impedance by "k4pf@juno.com" 14) Re: 75A-4 Filter impedance by Al Klase 15) Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver by Jerry Proc 16) RE: Recovering "Bumble Bee" Capacitors by wa1kbq@aol.com 17) Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver by HankVC ---------------------------------------------------------------------- Message-id: <4BA24C42.2000902@ar88.net> Date: Thu, 18 Mar 2010 11:52:34 -0400 From: Al Klase MIME-version: 1.0 To: Old Tube Radios Cc: Old Tube Radios Subject: Re: 75A-4 Filter impedance Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit (This reflector is really starting to annoy me with it's inability to deal with 21st century email practices! This is total BS!) A couple thousand ohms. But, you're asking a "loaded" question, and need to explain what the real question is. Al On 3/18/2010 10:41 AM, John Oglesby wrote: > I tried looking for this answer in the archives, but had problems > accessing the files. So - I thought this might be an easy question > for someone on the list. What is the input impedance expected by a > 75A-4 filter? > > Thanks and 73 > > John > N9RE > -- Al Klase - N3FRQ Jersey City, NJ http://www.skywaves.ar88.net/ ------------------------------ Message-ID: <220407.5172.qm@web56701.mail.re3.yahoo.com> Date: Thu, 18 Mar 2010 10:37:33 -0700 (PDT) From: Meyer Gottesman Subject: Meyer Gottesman re: 75A-4 for sale. To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-468509424-1268933853=:5172" --0-468509424-1268933853=:5172 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello:=0A=0AI;d like to sell my 75A4 receiver. It has now a 3 wire line cor= d. Three filters. Coveted high serial number of 48xx. Copy of manual. 4:1 t= uning knob. Seemingly in perfect condition. $1,500 plus shipping=A0or can b= e picked up in Macon, Georgia.=0A=0ATel: (478) 741-1710l=0A=0A73=0A=0AMeyer= Gottesman, W6GIV=0A=0A=0A --0-468509424-1268933853=:5172 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 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * --0-468509424-1268933853=:5172-- ------------------------------ Message-ID: <4BA27FB7.6070701@charter.net> Date: Thu, 18 Mar 2010 15:32:07 -0400 From: John Oglesby MIME-Version: 1.0 To: Old Tube Radios Subject: Re: 75A-4 Filter impedance Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Al - My 75A-4 only has the 2.1KHz filter and I have some other Collins mechanical filters that I could use, but I want to have them match the circuit impedance so the passband won't get screwed up. I know that the Curry filters have to use a matching network and I expect I will have to do so as well. - John John On 3/18/2010 11:52 AM, Al Klase wrote: > (This reflector is really starting to annoy me with it's inability to > deal with 21st century email practices! This is total BS!) > > A couple thousand ohms. But, you're asking a "loaded" question, and need > to explain what the real question is. > > Al > > On 3/18/2010 10:41 AM, John Oglesby wrote: >> I tried looking for this answer in the archives, but had problems >> accessing the files. So - I thought this might be an easy question for >> someone on the list. What is the input impedance expected by a 75A-4 >> filter? >> >> Thanks and 73 >> >> John >> N9RE >> > ------------------------------ Message-ID: <001201cac6dd$25d15bb0$969d480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Recovering "Bumble Bee" Capacitors Date: Thu, 18 Mar 2010 13:54:00 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit > ......The question of something electrical going-on with the water absorbed into the Bakelite is still open, too. .... The answer is blowing in the wind: hy·gro·scop·ic (hì´gre-skòp¹îk) adjective Readily absorbing moisture, as from the atmosphere. - hy´gro·scop¹i·cal·ly adverb - hy´gro·sco·pic¹i·ty (-skò-pîs¹î-tê) noun Arden Allen KB6NAX Adopt a shelter dog, save an innocent life, and make a friend forever =:-) ------------------------------ Message-ID: <003101cac6de$b5bcf760$969d480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Cc: "Old Tube Radios" Subject: Re: Recovering "Bumble Bee" Capacitors Date: Thu, 18 Mar 2010 14:00:18 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > ....A human failing certainly not unique to engineers...... :^) Having worked approximately half my career directly for design engineers I have many scars from engineers who were just the opposite. They were more focused on the political forest than the job requirement trees. I liked working for the tree huggers ;-) Arden Allen KB6NAX Adopt a shelter dog, save an innocent life, and make a friend forever =:-) ------------------------------ Message-ID: From: "JAMES HANLON" To: Old Tube Radios Subject: UV202 question Date: Thu, 18 Mar 2010 17:44:51 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006F_01CAC6C2.B64FD240" This is a multi-part message in MIME format. ------=_NextPart_000_006F_01CAC6C2.B64FD240 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Y'all, How much power would a kid in 1922 have run to a Hartley Oscillator = using an RCA UV202 "5-watt" tube? It's for an ER article. Thanks, Jim, W8KGI ------=_NextPart_000_006F_01CAC6C2.B64FD240 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_006F_01CAC6C2.B64FD240-- ------------------------------ Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Subject: RE: UV202 question Date: Thu, 18 Mar 2010 19:35:38 -0500 Message-ID: From: "Singley, Rodger" To: Old Tube Radios Jim, There is an article in February '24 QST showing a station running 6 of = these "5-watters" in parallel and states it was run at 800 watts input = during the 1923 transatlantic tests. =20 Herbert Johnson of Swan must have been inspired by these early = experiments :) Rodger WQ9E -----Original Message----- From: owner-boatanchors@theporch.com on behalf of JAMES HANLON Sent: Thu 3/18/2010 6:44 PM To: Old Tube Radios Subject: UV202 question =20 Y'all, How much power would a kid in 1922 have run to a Hartley Oscillator = using an RCA UV202 "5-watt" tube? It's for an ER article. Thanks, Jim, W8KGI ------------------------------ Date: Thu, 18 Mar 2010 22:48:54 -0800 To: Old Tube Radios From: John Kolb Subject: Re: 75A-4 Filter impedance Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Message-Id: <20100319054856.B18D53E28@wellington.concentric.com> I don't have specific specs for the 75A-4 filters, but all the filters I've seen of that age were for 100K impedance. To use a more modern low impedance filter, matching would be necessary, as is done in the Curry filters. John At 06:41 AM 3/18/2010, John Oglesby wrote: >I tried looking for this answer in the archives, but had problems >accessing the files. So - I thought this might be an easy question >for someone on the list. What is the input impedance expected by a >75A-4 filter? > >Thanks and 73 > >John >N9RE ------------------------------ Date: Thu, 18 Mar 2010 22:45:35 -0800 To: Old Tube Radios From: John Kolb Subject: Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Message-Id: <20100319054833.A91963D7B@wellington.concentric.com> I haven't seen my copy of Sibley's "Tube Lore" for years, but according to vacuumtubesinc, 200 series tube numbers were made by RCA and a few others. http://www.vacuumtubesinc.com/TubeTidbits/AntiqueTubeEquivalents.aspx John At 03:59 AM 3/18/2010, Jerry Proc wrote: >Hi Scott, > >I suspect you might be correct. It would be impossible to purchase >types 236, 237 and 238 *as* receiving tubes because they never >existed. So the '2 prefix must be something specific to Canadian >Marconi. Yours is the only response from 2 mail lists, so this must >be a very obscure piece of info. > >If no other replies arrive, I will simply ammend the text to >indicate the the receiver uses type 36, 37 and 38 tubes whose >identity is noted as '236, '237 and '238 on the schematic. > > >-- >Regards, >Jerry Proc >E-mail: jerry7proc@yahoo.com ------------------------------ Mime-Version: 1.0 Message-Id: Date: Fri, 19 Mar 2010 00:52:16 -0700 To: Old Tube Radios From: Scott Robinson Subject: Re: 75A-4 Filter impedance Content-Type: text/plain; charset="us-ascii" ; format="flowed" Hi John, I think that there were articles in mid-50s QST and so forth describing conversions to install these filters in other receivers, and those would have the impedance stated. I did read such an article a year or two back, and I recall either 1500 ohms or 15K, not the 100K mentioned by another lister. Someone with QSTs (not me, I don't have them) might look it up. I do have access to QST, but not at home and not conveniently, so I'd like to nominate someone else to do this research. Good luck, Scott > > >At 06:41 AM 3/18/2010, John Oglesby wrote: >>I tried looking for this answer in the archives, but had problems >>accessing the files. So - I thought this might be an easy question >>for someone on the list. What is the input impedance expected by a >>75A-4 filter? >> >>Thanks and 73 >> >>John >>N9RE ------------------------------ Message-ID: <4BA39ADC.8070801@charter.net> Date: Fri, 19 Mar 2010 11:40:12 -0400 From: John Oglesby MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: 75A-4 Filter impedance Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Scott - Good idea on the QST source. I looked in all of my Electric Radios and old 75A-4 Ham Radio articles and didn't see anything. From the discussion and looking at the circuit I think some 455KHz transformers HiZ/LowZ on each end would do the trick. John On 3/19/2010 3:52 AM, Scott Robinson wrote: > Hi John, > > I think that there were articles in mid-50s QST and so forth describing > conversions to install these filters in other receivers, and those would > have the impedance stated. > > I did read such an article a year or two back, and I recall either 1500 > ohms or 15K, not the 100K mentioned by another lister. Someone with QSTs > (not me, I don't have them) might look it up. I do have access to QST, > but not at home and not conveniently, so I'd like to nominate someone > else to do this research. > > Good luck, > > Scott >> >> >> At 06:41 AM 3/18/2010, John Oglesby wrote: >>> I tried looking for this answer in the archives, but had problems >>> accessing the files. So - I thought this might be an easy question >>> for someone on the list. What is the input impedance expected by a >>> 75A-4 filter? >>> >>> Thanks and 73 >>> >>> John >>> N9RE > > > ------------------------------ Message-ID: <14973563.1269018823061.JavaMail.root@elwamui-ovcar.atl.sa.earthlink.net> Date: Fri, 19 Mar 2010 10:13:42 -0700 (GMT-07:00) From: spr@earthlink.net To: Old Tube Radios Subject: Re: 75A-4 Filter impedance Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi John, I was thinking more of a cathode follower to drive and a resistive output load, since the output impedance of a pentode is high and poorly defined. Regards, Scott -----Original Message----- >From: John Oglesby >Sent: Mar 19, 2010 8:40 AM >To: spr@earthlink.net >Cc: Old Tube Radios >Subject: Re: 75A-4 Filter impedance > >Scott - Good idea on the QST source. I looked in all of my Electric >Radios and old 75A-4 Ham Radio articles and didn't see anything. From >the discussion and looking at the circuit I think some 455KHz >transformers HiZ/LowZ on each end would do the trick. > >John > > >On 3/19/2010 3:52 AM, Scott Robinson wrote: >> Hi John, >> >> I think that there were articles in mid-50s QST and so forth describing >> conversions to install these filters in other receivers, and those would >> have the impedance stated. >> >> I did read such an article a year or two back, and I recall either 1500 >> ohms or 15K, not the 100K mentioned by another lister. Someone with QSTs >> (not me, I don't have them) might look it up. I do have access to QST, >> but not at home and not conveniently, so I'd like to nominate someone >> else to do this research. >> >> Good luck, >> >> Scott >>> >>> >>> At 06:41 AM 3/18/2010, John Oglesby wrote: >>>> I tried looking for this answer in the archives, but had problems >>>> accessing the files. So - I thought this might be an easy question >>>> for someone on the list. What is the input impedance expected by a >>>> 75A-4 filter? >>>> >>>> Thanks and 73 >>>> >>>> John >>>> N9RE >> >> >> > > ------------------------------ Mime-Version: 1.0 From: "k4pf@juno.com" Date: Fri, 19 Mar 2010 20:15:44 GMT To: Old Tube Radios Subject: Re: 75A-4 Filter impedance Message-Id: <20100319.161544.1341.0@webmail20.vgs.untd.com> Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Content-Type: text/plain; charset=ISO-8859-1 John Oglesby wrote >Scott - Good idea on the QST source. I looked in all of my Electric = Radios and old 75A-4 Ham Radio articles and didn't see anything. From = the discussion and looking at the circuit I think some 455KHz = transformers HiZ/LowZ on each end would do the trick. Hi, GE "Ham News", March-April 1957 edition, published a receiver adapter using a Collins F455J-31 mechanical filter: http://bama.edebris.com/manuals/gehamnews/ge1202/ They didn't state the impedance. The adapter used 6BA6's and a parallel LC circuit at the input and output of the mechanical filter. 73, Ed Knobloch ------------------------------ Message-id: <4BA3E53B.3080501@ar88.net> Date: Fri, 19 Mar 2010 16:57:31 -0400 From: Al Klase MIME-version: 1.0 To: Old Tube Radios Cc: Old Tube Radios Subject: Re: 75A-4 Filter impedance Content-type: multipart/alternative; boundary=------------080909060802080808060708 This is a multi-part message in MIME format. --------------080909060802080808060708 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Well, that's essentially the circuit that already exists in the 75A-4. The question is how to plug in the modern filters designed to work with transistors. The important thing is the matching-network topology the commercial guys like Curry are using to retrofit the current Collins products. Fer instance, if you know a Pi-net will do the job, it's pretty easy to back into the appropriate values. A broad-band transformer with about a 20:1 turns ration might do the trick as well.. Al On 3/19/2010 4:15 PM, k4pf@juno.com wrote: > John Oglesby wrote > >> Scott - Good idea on the QST source. I looked in all of my Electric >> > Radios and old 75A-4 Ham Radio articles and didn't see anything. From > the discussion and looking at the circuit I think some 455KHz > transformers HiZ/LowZ on each end would do the trick. > > Hi, > > GE "Ham News", March-April 1957 edition, published a receiver adapter > using a Collins F455J-31 mechanical filter: > http://bama.edebris.com/manuals/gehamnews/ge1202/ > > They didn't state the impedance. The adapter used 6BA6's > and a parallel LC circuit at the input and output > of the mechanical filter. > > 73, > Ed Knobloch > > -- Al Klase - N3FRQ Jersey City, NJ http://www.skywaves.ar88.net/ --------------080909060802080808060708 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 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * --------------080909060802080808060708-- ------------------------------ Message-ID: <819561.8929.qm@web112312.mail.gq1.yahoo.com> Date: Fri, 19 Mar 2010 15:03:18 -0700 (PDT) From: Jerry Proc Subject: Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver To: Old Tube Radios MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi John, Yes...that's it. Thank you... The 2 as the leading digit in the type indica= tes it was made by RCA according to the web site. I'm now guessing the apos= trophe on the schematic means RCA since the draftsman probably didn't want = to write out the three letters each time. =20 -- Regards, Jerry Proc E-mail: jerry7proc@yahoo.com --- On Fri, 3/19/10, John Kolb wrote: > From: John Kolb > Subject: Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver > To: "Old Tube Radios" > Received: Friday, March 19, 2010, 2:45 AM >=20 > I haven't seen my copy of Sibley's "Tube Lore" for years, > but according to > vacuumtubesinc, 200 series tube numbers were made by RCA > and a few others. > http://www.vacuumtubesinc.com/TubeTidbits/AntiqueTubeEquivalents.aspx >=20 > John >=20 > At 03:59 AM 3/18/2010, Jerry Proc wrote: > > Hi Scott, > >=20 > > I suspect you might be correct. It would be impossible > to purchase types 236, 237 and 238 *as* receiving tubes > because they never existed.=A0 So the '2 prefix must be > something specific to Canadian Marconi. Yours is the only > response from 2 mail lists, so this must be a very obscure > piece of info. > >=20 > > If no other replies arrive, I will simply ammend the > text to indicate the the receiver uses type 36, 37 and 38 > tubes whose identity is noted as '236, '237 and '238 on the > schematic. > >=20 > >=20 > > -- > > Regards, > > Jerry Proc > > E-mail: jerry7proc@yahoo.com >=20 > =0A=0A=0A __________________________________________________________= ________=0ABe smarter than spam. See how smart SpamGuard is at giving junk = email the boot with the All-new Yahoo! Mail. Click on Options in Mail and = switch to New Mail today or register for free at http://mail.yahoo.ca ------------------------------ To: Old Tube Radios Subject: RE: Recovering "Bumble Bee" Capacitors Date: Sat, 20 Mar 2010 07:42:41 -0400 MIME-Version: 1.0 From: wa1kbq@aol.com Content-Type: multipart/alternative; boundary="--------MB_8CC963995607F50_9E8_1A550_webmail-m022.sysops.aol.com" Message-Id: <8CC963995014828-9E8-D89B@webmail-m022.sysops.aol.com> ----------MB_8CC963995607F50_9E8_1A550_webmail-m022.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" Ed, Would it be possible to get Doug to give us an engineering description why= these caps are "real crap"? An engineer's goal many times is to achieve?$= 10.00 worth of results from $1.00 worth of materials. Did Sprague miss the= boat on this one or did the?capacitor meet original engineering design re= quirements at the time? ? Regards, Greg -----Original Message----- From: Ed Sieb <esieb@sympatico.ca> To: Old Tube Radios <boatanchors@theporch.com> Sent: Thu, Mar 18, 2010 4:18 am Subject: RE: Recovering "Bumble Bee" Capacitors de Ed, VA3ES=20 Hoo boy! =20 Well, I showed this thread to my good friend, Doug Bannard, VE3SPF, who= is =20 an electrical engineer, and a PE. He has extensive experience with =20 "Bumble-Bees" and "Black Beauties". Here is his response:=20 =20 =20 =20 -----Original Message-----=20 From: Doug Bannard [mailto:ve3spf@rogers.com]=20 Sent: March 17, 2010 5:39 PM=20 To: Ed Sieb; Carl Morin VA3CGM=20 Subject: Re: Recovering "Bumble Bee" Capacitors=20 =20 =20 This goes to show how a little knowledge is a dangerous thing indeed. The= =20 leakage is caused by aluminum migration through the sulphite pulp based = =20 kraft paper dielectric. Any moisture only serves to facilitate the =20 degradation and is not its root cause.=20 =20 A leakage current of 10 microamperes at 400 volts is NOT a low value of = =20 leakage and is totally unacceptable. This represents a leakage resistance= =20 of only 40 megohms, and if used as a coupling cap will almost certainly = =20 upset the grid bias on the next stage. If they were to show leakage =20 currents with 400 volts of applied DC of 0.1 microamps this would represen= t =20 a leakage resistance of 4000 megohms and would be MARGINALLY acceptable.= =20 =20 Not to put too fine a point on it, bumblebee caps are real crap and the on= ly =20 place for them is either in a (non-functional) display item or in the garb= age =20 wagon.=20 =20 =20 73...Doug Bannard=20 =20 ----------MB_8CC963995607F50_9E8_1A550_webmail-m022.sysops.aol.com Content-Transfer-Encoding: quoted-printable 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 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ----------MB_8CC963995607F50_9E8_1A550_webmail-m022.sysops.aol.com-- ------------------------------ From: HankVC Message-Id: <201003201436.o2KEa4Gi011419@julie.lostwells.net> Subject: Re: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver To: Old Tube Radios Date: Sat, 20 Mar 2010 08:36:04 -0600 (MDT) Cc: boatanchors@theporch.com (Old Tube Radios) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit The esteemed spr@earthlink.net has said: > > > -----Original Message----- > >From: Jerry Proc > >Subject: Canadian Marconi Y.S.W.- 4A2 Shortwave Receiver > > > >The Canadian Marconi Y.S.W.- 4A2 shortwave receiver is the latest addition to my Canadian Marconi virtual museum. > > > >This particular receiver was factory modified (in 1933)to use automotive type tubes and a letter to that effect accompanied the receiver. It uses '236, '237 and '238 type types in the lineup. I am unable to locate these types in the *Prehistory section* (pg 9) of Tube Lore by Ludwell Sibley. > > > >Types 36, 37 and 38, appear to be automotive tubes since thay all sport 6.3 volt filaments. On the schematic diagram, why are the tube type labels prefixed with an apostrophe? Is this a short form for something? > > > >-- > >Jerry Proc > > > > I think the '2' prefix, as is 236, only designates the manufacturer of the tube. The apostrophe must be one of those 'north of the border' things... > > Scott > I think the older tube designations were discussed to some extent by Ghirardi in "Radio Physics Course" (1932). What sticks in my mind runs along these lines: Designation format was LLmnn where LL was UV/X/Y, m was a manufacturer ID, and nn was the tube type number. Manufacturers I recall are Western Electric=1, RCA patent pool = 2, Cunningham = 3. V/X/Y were basing designattions: V for nub-pin bayonet, X for plug-in 4-pin; Y for 5-pin. After 1932, only the tube type number was used. Thus: UV199 was the tubular 4 nub-pin bayonet triode originally developed by Western Electric for a telephone amplifier ca. 1918. UX199 was the same tube with a 4-pin plug-in base. Later called V99 and X99, with the basing designation included because there were two for that tube. UX200 and UX201 were globe-bottle triodes with 4-pin plug-in bases, developed ca. 1920. The 200 was a "soft vacuum" version of the 201, for use in grid leak detectors. The UX201, which had a long run, was updated in manufacture to become the UX201A. Cunningham-manufacture of that tube was designated CX301. The familiar term for that tube later on was '01A, with or without the apostrophe So you'll recognize UX280 as the long-lived 80 rectifier, UX245 as a 45 power triode, and UX171, which also got beefed up, as the 71A. Letter Y designates a 5-pin base, such as UY227 for type 27, and UY247 for the 47 power pentode. Readers will recognize UY224 as the 24A---the A suffix coming when the tubes were built with treated plates to reduce secondary emission and the negative resistance knee in the plate resistance curve. The orphan in the above was the WD11, which had a non-standard base. Can't recall, offhand, that tube's provenance, but I think it was a Western Electric. Worth remembering here that RCA was a patent pool corporation, not a manufacturer, until they bought the Victor Talking Machine Co. in 1928. So the early RCA superheterodyne receivers with the catacombs potted chassis and V99 tubes were actually built by GE and Westinghouse. As I recall, the shift to the n-l-n designators, such as 2A3 and 2A7 came in 1932. Thus there are the 57/58 2.5 volt pentodes, 77/78 the same tubes with 6.3 volt heaters, but the 6C6 and 6D6 didn't have 2.5 volt equivalents. So it would seem to me that prefacing "236" with an apostrophe to denote dropping the two-letter basing prefix would be understandable in the early-mid 1930's. Things like that came along with the revision of the drafting standards for tube internals to show the plate as a straight horizontal line at the top rather than a rectangle on one side, and the grids as horizontal dashed lines, a general standardization of broadcast IF frequencies in the 450-470 Kc range, and the wholesale shift from 2.5 to 6.3 volt heaters. Hank ------------------------------ End of BOATANCHORS Digest 4326 ******************************