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Variable selectivity?
I wonder if anyone can offer a picture of the variable selectivity
arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. |
Variable selectivity?
"gareth" wrote in message
... I wonder if anyone can offer a picture of the variable selectivity arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. You might find something here. www.eddystoneusergroup.org.uk Number 15 "Inductor lore" J -- "How we have advanced, thanks to the Machine!" said Vashti. "The Machine Stops" - 1909 |
Variable selectivity?
"Mantrid" wrote in message
... "gareth" wrote in message ... I wonder if anyone can offer a picture of the variable selectivity arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. You might find something here. www.eddystoneusergroup.org.uk Number 15 "Inductor lore" I should have said, Restoration Projects, then Number 15 J -- "How we have advanced, thanks to the Machine!" said Vashti. "The Machine Stops" - 1909 |
Variable selectivity?
"Mantrid" wrote in message
... "Mantrid" wrote in message ... "gareth" wrote in message ... I wonder if anyone can offer a picture of the variable selectivity arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. You might find something here. www.eddystoneusergroup.org.uk Number 15 "Inductor lore" I should have said, Restoration Projects, then Number 15 Well done, that man! Actually, "No5 Crystal filters and receiver selectivity" has the desired photo. Many thanks. |
Variable selectivity?
"gareth" wrote in message
... "Mantrid" wrote in message ... "Mantrid" wrote in message ... "gareth" wrote in message ... I wonder if anyone can offer a picture of the variable selectivity arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. You might find something here. www.eddystoneusergroup.org.uk Number 15 "Inductor lore" I should have said, Restoration Projects, then Number 15 Well done, that man! Actually, "No5 Crystal filters and receiver selectivity" has the desired photo. Many thanks. .... AND ... a very good explanation of the Eddystone dial, to boot! |
Variable selectivity?
On 05/10/13 17:12, gareth wrote:
... AND ... a very good explanation of the Eddystone dial, to boot! "To boot" seems quite apt for you, old Bean. -- ;-) .. 73 de Frank Turner-Smith G3VKI - mine's a pint. .. http://turner-smith.co.uk .. Ubuntu 12.04 Thunderbirds are go. |
Variable selectivity?
Frank Turner-Smith G3VKI wrote:
On 05/10/13 17:12, gareth wrote: ... AND ... a very good explanation of the Eddystone dial, to boot! "To boot" seems quite apt for you, old Bean. Gareth would turn the other cheek, but it's hard to do that when a copper's got your head pinned to the floor with his size 12 standard issue. -- If the above message is full of spelling mistakes or the snipping is duff, it's probably because it was sent from my iPhone, likely whilst walking. Apologies! |
Variable selectivity?
"To boot" seems quite apt for you, old Bean. Gareth would turn the other cheek, but it's hard to do that when a copper's got your head pinned to the floor with his size 12 standard issue. probably one of the last few things he did before he topped himself............... |
Variable selectivity?
"Jimbo..." wrote in message
... "To boot" seems quite apt for you, old Bean. Gareth would turn the other cheek, but it's hard to do that when a copper's got your head pinned to the floor with his size 12 standard issue. probably one of the last few things he did before he topped himself............... The fact that the plods videoed the arrest tells me that they were expecting, and got, problems. More recent allegations of attacking postmen etc confirm their need for caution. That plod had no need to top himself over an incident in which he lost his cool while dealing with an idiot. He had been acquitted and IMHO should have brought counter-charges for defamation. -- ;-) .. 73 de Frank Turner-Smith G3VKI - mine's a pint. .. http://turner-smith.co.uk |
Variable selectivity?
"FranK Turner-Smith G3VKI" wrote in message ... "Jimbo..." wrote in message ... "To boot" seems quite apt for you, old Bean. Gareth would turn the other cheek, but it's hard to do that when a copper's got your head pinned to the floor with his size 12 standard issue. probably one of the last few things he did before he topped himself............... The fact that the plods videoed the arrest tells me that they were expecting, and got, problems. More recent allegations of attacking postmen etc confirm their need for caution. That plod had no need to top himself over an incident in which he lost his cool while dealing with an idiot. He had been acquitted and IMHO should have brought counter-charges for defamation. ;-) . 73 de Frank Turner-Smith G3VKI - mine's a pint. I blame the freemasons in the polis....... |
Variable selectivity?
On 06/10/13 13:28, Jimbo... wrote:
"FranK Turner-Smith G3VKI" wrote in message ... "Jimbo..." wrote in message ... "To boot" seems quite apt for you, old Bean. Gareth would turn the other cheek, but it's hard to do that when a copper's got your head pinned to the floor with his size 12 standard issue. probably one of the last few things he did before he topped himself............... The fact that the plods videoed the arrest tells me that they were expecting, and got, problems. More recent allegations of attacking postmen etc confirm their need for caution. That plod had no need to top himself over an incident in which he lost his cool while dealing with an idiot. He had been acquitted and IMHO should have brought counter-charges for defamation. ;-) . 73 de Frank Turner-Smith G3VKI - mine's a pint. I blame the freemasons in the polis....... Not the RSGB? -- ;-) .. 73 de Frank Turner-Smith G3VKI - mine's a pint. .. http://turner-smith.co.uk .. Ubuntu 12.04 Thunderbirds are go. |
Variable selectivity?
WOW!
A very full response, thank-you. "Richard Knoppow" wrote in message ... "gareth" wrote in message ... I wonder if anyone can offer a picture of the variable selectivity arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. This is the same arrangement used by Hammarlund in the Super-Pro series. Its been too long since I had a Super-Pro IF can open to remember exactly how the movable coils were fastened and guided but the variation was done by a post coming out the bottom of the can and operated by a cam on a shaft turned by the front panel "selectivity" knob. Very simple mechanism. This type of variable selectivity is the only one with completely symmetrical expansion of the passband. Those using tapped inductances coupled to the IF coils, such as used in the SP-600-JX and RCA AR-88, are nearly as good. Capacitance coupling usually results in some asymmetry as seen in some Hallicrafters receivers although the variable pass band in the SX-28 works quite well. Later in this thread someone asks about variable crystal filters. There are essentially two forms: the original Lamb filter and the later one patented by Hammarlund in 1938 and first used in the HQ-120-X. The Hammarlund filter has the advantage that the center frequency does not vary with the bandwidth adjustment or when the phasing null is moved around. The Hammarlund circuit was used in the SP-200, 400 and 600 Super Pro receivers as well as the HQ series and, in slightly modified form, by TMC in the GPR-90 and by Collins in the 75A-1,2,3 and 51J series. National and Hallicrafters mostly used the earlier Lamb circuit. as did Hammarlund in the SP-100 Super-Pro. -- -- Richard Knoppow Los Angeles WB6KBL |
Variable selectivity?
"gareth" wrote in message
... WOW! A very full response, thank-you. Let's go Beanie, let's go. |
Variable selectivity?
"gareth" wrote in message ... WOW! A very full response, thank-you. After I posted this I realized that I forgot a part. In the Super-Pro there is a phenolic lever between the rotating cam and the rods from the movable coils. I am not sure why the rods are not moved directly by the cams. I think Hammarlund had a patent on the IF variation system but I don't have the number. The Hammarlund crystal filter is described in _QST_ Dec 1938, p.33 D.K. Oram "Full Range Selectivity with the 455 khc Crystal Filter" Oram's patent is USP 2222043 You can get patents by number from the U.S. Patent and Trade Mark Office or from Google Patents. The Google site has the advantage that patents are searchable by text for _all_ dates and are available in PDF form. I also have the Lamb patents but it will take some searching since my file is organized by patent number and not title. However, they are easily found by doing a Google search for James Lamb. You will also find his patent for the famous Lamb Noise Blanker. Lamb had more than one patent on crystal filters and wrote extensively about them in the early thirties editions of QST. AFAIK, the first application of the Lamb filter was in the HRO. The first Hammarlund filter was in the HQ-120-X and it was later applied to the Super-Pro. Some Series 100 Super-Pros have crystal filters as an add-on but these are not the later version. BTW, the Lamb patent was licensed to James Millen. At the time he was one of the principles of the National Radio company and is supposed to have been responsible for the mechanical design of the HRO. -- -- Richard Knoppow Los Angeles WB6KBL |
Variable selectivity?
Further information most welcome, thank-you
In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? "Richard Knoppow" wrote in message m... "gareth" wrote in message ... WOW! A very full response, thank-you. After I posted this I realized that I forgot a part. In the Super-Pro there is a phenolic lever between the rotating cam and the rods from the movable coils. I am not sure why the rods are not moved directly by the cams. I think Hammarlund had a patent on the IF variation system but I don't have the number. The Hammarlund crystal filter is described in _QST_ Dec 1938, p.33 D.K. Oram "Full Range Selectivity with the 455 khc Crystal Filter" Oram's patent is USP 2222043 You can get patents by number from the U.S. Patent and Trade Mark Office or from Google Patents. The Google site has the advantage that patents are searchable by text for _all_ dates and are available in PDF form. I also have the Lamb patents but it will take some searching since my file is organized by patent number and not title. However, they are easily found by doing a Google search for James Lamb. You will also find his patent for the famous Lamb Noise Blanker. Lamb had more than one patent on crystal filters and wrote extensively about them in the early thirties editions of QST. AFAIK, the first application of the Lamb filter was in the HRO. The first Hammarlund filter was in the HQ-120-X and it was later applied to the Super-Pro. Some Series 100 Super-Pros have crystal filters as an add-on but these are not the later version. BTW, the Lamb patent was licensed to James Millen. At the time he was one of the principles of the National Radio company and is supposed to have been responsible for the mechanical design of the HRO. -- -- Richard Knoppow Los Angeles WB6KBL |
Variable selectivity?
"gareth" wrote in message ... Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? I think this was part of Lamb's original intention. The articles originally describing the use of the filter were aimed at "single signal" reception, meaning that the audio image was suppressed. The Lamb filter required some juggling between the bandwidth and phasing adjustments to get the response to where the operator wanted it since they interacted with each other and with the center frequency. Nonetheless, the filter worked very well and provided an order of magnitude better selectivity than was available previously. James Millen was one of the founders of National but eventually was pushed out of the company. He started his own company, also in Malden Mass, and probably made many parts for National as well as his own stuff. Millen made very high quality components. There is considerable history of both National and Millen, including a Millen Society, on the web, a Google search will find it. The National HRO was a revolutionary receiver in its day and stayed one of the favorites for both ham and commercial use for some thirty years. The mechanical design is attributed mostly to James Millen and the electronic design mostly to Herbert Hoover Jr., son of the president of the US. -- -- Richard Knoppow Los Angeles WB6KBL |
Variable selectivity?
"Richard Knoppow" wrote in message
... "gareth" wrote in message ... Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? I think this was part of Lamb's original intention. The articles originally describing the use of the filter were aimed at "single signal" reception, meaning that the audio image was suppressed. The Lamb filter required some juggling between the bandwidth and phasing adjustments to get the response to where the operator wanted it since they interacted with each other and with the center frequency. Nonetheless, the filter worked very well and provided an order of magnitude better selectivity than was available previously. James Millen was one of the founders of National but eventually was pushed out of the company. He started his own company, also in Malden Mass, and probably made many parts for National as well as his own stuff. Millen made very high quality components. There is considerable history of both National and Millen, including a Millen Society, on the web, a Google search will find it. The National HRO was a revolutionary receiver in its day and stayed one of the favorites for both ham and commercial use for some thirty years. The mechanical design is attributed mostly to James Millen and the electronic design mostly to Herbert Hoover Jr., son of the president of the US. I'm in the process of making a retro RX, primarily because I've a junk box going back 50 years and if I don't do something with the bits now, then the executor of my will is likely to skip the lot. I recently analysed the Sperry PWD dial from the HRO, and conceived of a way to reproduce it, but without needing an internal toother ring. However, my tastes have changed, and I'm now heading for an RX that is similar in style to the Eddystone EA12. But the one thing that I owe to the National design in my musings is the possibility of emulating the Catacomb from the NC100X RX, as the means of simplifying the wiring of a bandswitch. I was originally interested in the variable selectivity of the Eddystone, and, indeed, have obtained a photo of the innards of one of the variable IF transformers, but I think that I'll do a coouple of ladder filters based on modern practice, with both SSB and CW versions. Once again, very interesting articles from you, thanks! Gareth G4SDW |
Variable selectivity?
"gareth" wrote in message
... I'm in the process of making a retro RX, primarily because I've a junk box going back 50 years and if I don't do something with the bits now, then the executor of my will is likely to skip the lot. I recently analysed the Sperry PWD dial from the HRO, and conceived of a way to reproduce it, but without needing an internal toother ring. However, my tastes have changed, and I'm now heading for an RX that is similar in style to the Eddystone EA12. But the one thing that I owe to the National design in my musings is the possibility of emulating the Catacomb from the NC100X RX, as the means of simplifying the wiring of a bandswitch. I was originally interested in the variable selectivity of the Eddystone, and, indeed, have obtained a photo of the innards of one of the variable IF transformers, but I think that I'll do a coouple of ladder filters based on modern practice, with both SSB and CW versions. Once again, very interesting articles from you, thanks! Gareth G4SDW Let's go Beanie, let's go. |
Variable selectivity?
"gareth" wrote in message
... Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? Let's go Beanie, let's go. |
Variable selectivity?
In article ,
gareth wrote: Path: eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: "gareth" Newsgroups: rec.radio.amateur.boatanchors,uk.radio.amateur Subject: Variable selectivity? Date: Sun, 13 Oct 2013 19:11:43 +0100 Organization: A noiseless patient Spider Lines: 62 Message-ID: References: Injection-Date: Sun, 13 Oct 2013 18:11:44 +0000 (UTC) Injection-Info: mx05.eternal-september.org; posting-host="7eed01e16f1b726e7bf0868184e40653"; logging-data="3180"; "; posting-account="U2FsdGVkX1+1JzqQMmyCzyCfOW7Zs0Hn/3jBXvXa3C4=" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-RFC2646: Format=Flowed; Response X-Newsreader: Microsoft Outlook Express 6.00.2900.5931 Cancel-Lock: sha1:srPnYezJ15BqABsrB2fkVqKopN0= X-Priority: 3 X-MSMail-Priority: Normal Xref: news.eternal-september.org rec.radio.amateur.boatanchors:3527 uk.radio.amateur:189325 Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. I'm a bit surprised to see any doubt about James Millen as the honcho of National Company before 1939, his departure from National, and his setting up James Millen Manufacturing in Malden, Mass. a short distance from National in 1939-40. Yes, there was only one James Millen. There are a couple of web sites devoted to (Jim) Millen's history. I worked for James Millen Mfg. for a couple of years in the 1950's, so know a bit about Millen and some of the history behind the 1939 split with National. It was never entirely clear to me just what went on---on the one hand, a desire on the part of National's principal money backers to go public, and to move the company in different directions, with more consumer products; also, some financial things that reduced the money that Millen and his close associates (most or all of whom moved to Millen Mfg.) got from National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? I don't know about Hammarlund's variable coupling IF's in any detail, but I'd suspect that the interposition of a phenolic piece was for mechanical reasons, not electrical. Millen offered a line of IF transformers (455 and 1600 Khz) that used adjustable capacitive coupling only between the coils---one of my projects when I worked there. It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? So far as I know, Lamb's single signal focus was on CW reception with no audio content. As I recall, phasing the crystal filter came later. Early (1933-34) production receivers I know of that used Lamb's principles were the National AGS-X and FB-7X; and the RME-9D. Hank |
Variable selectivity?
In article ,
Richard Knoppow wrote: James Millen was one of the founders of National but eventually was pushed out of the company. He started his own company, also in Malden Mass, and probably made many parts for National as well as his own stuff. Millen made very high quality components. Millen Mfg., at least at the time I worked there, was in direct competition with National Co. on several products, and neither company supplied the other. The National HRO was a revolutionary receiver in its day and stayed one of the favorites for both ham and commercial use for some thirty years. The mechanical design is attributed mostly to James Millen and the electronic design mostly to Herbert Hoover Jr., son of the president of the US. While the HRO was a legendary product, I'd hardly call it "revolutionary." It was a follow-on to the AGS line, with objectives to maintain AGS performance at lower cost-to-manufacture, and to normalize the coil-set interface so that the tuning coils could be built all-in-one-box and interchangeable. An examination of the schematic will show it to be essentially a copy of higher-end home entertainment circuits of the era, with a crystal filter and bfo added. Much of the actual performance came from use of better coils (house-built) in the RF and IF stages, a house-built tuning capacitor, and the house-built tuning dial was superior to almost anything else around. In short, a relatively straightforward tried-and-proven electrical design, but extremely well-executed in component quality and mechanical structure, pretty much hallmarks of Jim Millen's team. Worth noting that the NC-100, National's follow-on product, had similar performance, with the advantage of having internally-mounted and switchable tuning coils. Hank |
Variable selectivity?
"Hank" wrote in message ... In article , Richard Knoppow wrote: James Millen was one of the founders of National but eventually was pushed out of the company. He started his own company, also in Malden Mass, and probably made many parts for National as well as his own stuff. Millen made very high quality components. Millen Mfg., at least at the time I worked there, was in direct competition with National Co. on several products, and neither company supplied the other. The National HRO was a revolutionary receiver in its day and stayed one of the favorites for both ham and commercial use for some thirty years. The mechanical design is attributed mostly to James Millen and the electronic design mostly to Herbert Hoover Jr., son of the president of the US. While the HRO was a legendary product, I'd hardly call it "revolutionary." It was a follow-on to the AGS line, with objectives to maintain AGS performance at lower cost-to-manufacture, and to normalize the coil-set interface so that the tuning coils could be built all-in-one-box and interchangeable. An examination of the schematic will show it to be essentially a copy of higher-end home entertainment circuits of the era, with a crystal filter and bfo added. Much of the actual performance came from use of better coils (house-built) in the RF and IF stages, a house-built tuning capacitor, and the house-built tuning dial was superior to almost anything else around. In short, a relatively straightforward tried-and-proven electrical design, but extremely well-executed in component quality and mechanical structure, pretty much hallmarks of Jim Millen's team. Worth noting that the NC-100, National's follow-on product, had similar performance, with the advantage of having internally-mounted and switchable tuning coils. Hank While the HRO had similar circuits to home receivers of the time I rather think there was not that much variation available. The HRO did use pentode mixers in place of hexode or pentagrid mixers resulting in low noise. The NC-100 was certainly a clever design but had only one RF so its image rejection is not as good as the HRO. I forgot to mention Dana Bacon another designer at National. I am not sure what contributions he made. -- -- Richard Knoppow Los Angeles WB6KBL |
Variable selectivity?
On Sun, 13 Oct 2013, gareth wrote:
Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? ONce again, "single signal selectivity" is credited to the Lamb filter, everyone referencs that famous QST article of his. You don't need the phasing control to get the single signal selectivity. Micahel VE2BVW |
Variable selectivity?
On Sun, 13 Oct 2013, Richard Knoppow wrote:
"gareth" wrote in message ... Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? I think this was part of Lamb's original intention. The articles originally describing the use of the filter were aimed at "single signal" reception, meaning that the audio image was suppressed. The Lamb filter required some juggling between the bandwidth and phasing adjustments to get the response to where the operator wanted it since they interacted with each other and with the center frequency. Nonetheless, the filter worked very well and provided an order of magnitude better selectivity than was available previously. James Millen was one of the founders of National but eventually was pushed out of the company. He started his own company, also in Malden Mass, and probably made many parts for National as well as his own stuff. Millen made very high quality components. There is considerable history of both National and Millen, including a Millen Society, on the web, a Google search will find it. The National HRO was a revolutionary receiver in its day and stayed one of the favorites for both ham and commercial use for some thirty years. The mechanical design is attributed mostly to James Millen and the electronic design mostly to Herbert Hoover Jr., son of the president of the US. And Hoover Jr. was president of the ARRL for a while. Michael VE2BVW |
Variable selectivity?
On Mon, 14 Oct 2013, Hank wrote:
In article , gareth wrote: Path: eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: "gareth" Newsgroups: rec.radio.amateur.boatanchors,uk.radio.amateur Subject: Variable selectivity? Date: Sun, 13 Oct 2013 19:11:43 +0100 Organization: A noiseless patient Spider Lines: 62 Message-ID: References: Injection-Date: Sun, 13 Oct 2013 18:11:44 +0000 (UTC) Injection-Info: mx05.eternal-september.org; posting-host="7eed01e16f1b726e7bf0868184e40653"; logging-data="3180"; "; posting-account="U2FsdGVkX1+1JzqQMmyCzyCfOW7Zs0Hn/3jBXvXa3C4=" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-RFC2646: Format=Flowed; Response X-Newsreader: Microsoft Outlook Express 6.00.2900.5931 Cancel-Lock: sha1:srPnYezJ15BqABsrB2fkVqKopN0= X-Priority: 3 X-MSMail-Priority: Normal Xref: news.eternal-september.org rec.radio.amateur.boatanchors:3527 uk.radio.amateur:189325 Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. I'm a bit surprised to see any doubt about James Millen as the honcho of National Company before 1939, his departure from National, and his setting up James Millen Manufacturing in Malden, Mass. a short distance from National in 1939-40. Yes, there was only one James Millen. There are a couple of web sites devoted to (Jim) Millen's history. I worked for James Millen Mfg. for a couple of years in the 1950's, so know a bit about Millen and some of the history behind the 1939 split with National. It was never entirely clear to me just what went on---on the one hand, a desire on the part of National's principal money backers to go public, and to move the company in different directions, with more consumer products; also, some financial things that reduced the money that Millen and his close associates (most or all of whom moved to Millen Mfg.) got from National. Millen was such a strong name by itself (I remember the single column ads in the back of QST in 1971 when I started reading it), I think it was only in recent years that I learned he had been part of National. That there was a connection between the two companies had always seemed obvious, though I assumed Millen had been like a subcontractor to supply parts to Natinoal. Millen probably was better off as a separate company, he could "design for excellence" and have his name more prominent. MIchael VE2BVW |
Variable selectivity?
On Mon, 14 Oct 2013, Richard Knoppow wrote:
"Hank" wrote in message ... In article , Richard Knoppow wrote: James Millen was one of the founders of National but eventually was pushed out of the company. He started his own company, also in Malden Mass, and probably made many parts for National as well as his own stuff. Millen made very high quality components. Millen Mfg., at least at the time I worked there, was in direct competition with National Co. on several products, and neither company supplied the other. The National HRO was a revolutionary receiver in its day and stayed one of the favorites for both ham and commercial use for some thirty years. The mechanical design is attributed mostly to James Millen and the electronic design mostly to Herbert Hoover Jr., son of the president of the US. While the HRO was a legendary product, I'd hardly call it "revolutionary." It was a follow-on to the AGS line, with objectives to maintain AGS performance at lower cost-to-manufacture, and to normalize the coil-set interface so that the tuning coils could be built all-in-one-box and interchangeable. An examination of the schematic will show it to be essentially a copy of higher-end home entertainment circuits of the era, with a crystal filter and bfo added. Much of the actual performance came from use of better coils (house-built) in the RF and IF stages, a house-built tuning capacitor, and the house-built tuning dial was superior to almost anything else around. In short, a relatively straightforward tried-and-proven electrical design, but extremely well-executed in component quality and mechanical structure, pretty much hallmarks of Jim Millen's team. Worth noting that the NC-100, National's follow-on product, had similar performance, with the advantage of having internally-mounted and switchable tuning coils. Hank While the HRO had similar circuits to home receivers of the time I rather think there was not that much variation available. The HRO did use pentode mixers in place of hexode or pentagrid mixers resulting in low noise. The NC-100 was certainly a clever design but had only one RF so its image rejection is not as good as the HRO. And that the HRO had two RF stages seems to be a significant factor. Even in the seventies, when Ray Moore wrote a number of articles about receiver design in Ham Radio magazine, he pointed out that one reason the HRO stood out was the 2 rf stages, which mean much better image rejection than the average receiver. The HRO-60 (or was it the 50?) added double conversion on the higher bands, but the earlier models were still contenders in that period for good image rejection on the higher bands. And of course, the design was good, so the extra stage actually helped rather than hindered. A superhet is a superhet, it's small details like this that made some better than others. A couple of years ago, I found at a garage sale for 2.00 a Grundig/Eton pocket shortwave receiver. It's a pretty crummy receiver, but without adding cost to it, they included a frequency counter. So a receiver probably as bad and as simple as my Hallicrafters S-120A from 1971 instantly gets a giant improvement in tuning because of that frequency counter. And once they did away with the analog dial, they could break the tuning segments up into smaller ranges, helping the tuning process. What initially complicates the receiver tremendously (or would if the frequency counter wasn't a single IC that also included a clock function and cost very little and took up little space), actually simplifies it. Today, you can stick with a 455KHz IF and then fuss over image rejection, or you can move to a higher IF and simplify the front end. Or go with double conversion, getting the easier image rejection, yet selectivity down where you can do things like use LC circuits. A single conversion receiver with 455KHz and one RF stage (if that) can't be much different from a circa 1930s receiver, communication or consumer, but you can now make simple receivers with other methods that actually mean better performance. It amazes me that over the past 7 years or so I've found shortwave receivers at rummage and garage sales, all nice and cheap, that are so much better than that 1971 Hallicrafters. Or even buy a new digitally tuned portable receiver for about the price I paid in 1971 for that Hallicrafters, and get nearly infinitely better capability. Michael VE2BVW |
Variable selectivity?
"Michael Black" wrote in message
xample.org... On Sun, 13 Oct 2013, gareth wrote: Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? ONce again, "single signal selectivity" is credited to the Lamb filter, everyone referencs that famous QST article of his. You don't need the phasing control to get the single signal selectivity. Incorrect. If the Xtal alone gave you single signal reception, then there'd be no advantage whatsoever in having the phasing control. That the phasing control can be used to null out other signals is the strong indication that more than the one signal is getting through the Xtal. Single Signal reception is the reference to the audio image being phased out. |
Variable selectivity?
On 14/10/2013 20:26, gareth wrote:
That the phasing control can be used to null out other signals is the strong indication that more than the one signal is getting through the Xtal. Surely the phasing control is there to allow the operator to introduce an antiphase of the unwanted signal(s) leaking *around* the crystal? |
Variable selectivity?
"gareth" wrote in message
... Incorrect. If the Xtal alone gave you single signal reception, then there'd be no advantage whatsoever in having the phasing control. That the phasing control can be used to null out other signals is the strong indication that more than the one signal is getting through the Xtal. Single Signal reception is the reference to the audio image being phased out. Let's go Beanie, let's go. |
Variable selectivity?
"gareth" wrote in message ... "Michael Black" wrote in message xample.org... On Sun, 13 Oct 2013, gareth wrote: Further information most welcome, thank-you In the 1948 Radio handbook which I mentioned previously, there are adverts from a company by the name of Millen, and I assumed it was the same guy after he had left National. Your comment about a phenolic intersperser is no doubt some means of isolating an earthy contact? It would be interesting to know from the Lamb patent whether he proposed therein the technique of Single Signal Reception by the use of the phasing control to null out the audio image, or whether this was something that came about through experience? ONce again, "single signal selectivity" is credited to the Lamb filter, everyone referencs that famous QST article of his. You don't need the phasing control to get the single signal selectivity. Incorrect. If the Xtal alone gave you single signal reception, then there'd be no advantage whatsoever in having the phasing control. That the phasing control can be used to null out other signals is the strong indication that more than the one signal is getting through the Xtal. Single Signal reception is the reference to the audio image being phased out. I have an RCA AR-88 receiver, this has a crystal filter but does not make the phasing adjustment available although there is one internally. The filter works quite well but the lack of the phasing adjustment to null out heterodynes is a distinct lack. In later versions of the receiver RCA did bring the control out the front panel but, because its not a balanced control, as is the Hammarlund and later Lamb filter, it doesn't work nearly as well. I suspect RCA was trying to avoid infringing the Lamb patent. The original Lamb filter when set for high selectivity, could cut out the audio image of a CW signal pretty well but, of course, the phasing control could be set specifically to null it out. Lamb wrote two or three articles in QST in the early thirties about improving the receivers available at the time and about single signal reception. You are right about the HRO not being the first receiver with a crystal filter. I am not sure which was but an earlier National receiver definitely had it as you point out. BTW, in searching for Lamb's patents earlier today I came across one I didn't know about: its essentially a mechanical filter using a rod with piezo electric drivers and pickups. Lamb describes a variable bandwidth IF using this filter for the medium wide band, a normal single crystal filter for the narrow band and a conventional IF transformer for the widest band. Curiously this patent is assigned to RCA. I didn't note the patent number but all of these can be found by searching Google Patents for James J. Lamb. -- -- Richard Knoppow Los Angeles WB6KBL |
Variable selectivity?
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Variable selectivity?
This is completely out of order, a posting about amateur radio on here,
almost unheard of! "gareth" wrote in message ... I wonder if anyone can offer a picture of the variable selectivity arrangement of the Eddystone EA12, which I believe was also used by some other manufacturers? This was the scheme whereby coupling between the primary and secondary of IF transformers was varied nechanically by distancing the two halves of the transformer from each other. I have access to photos showing the operating levers, but what interests me for the moment is to have a peek, or peeks, inside the IF cans themselves. |
Kenwood TS-130 Frequency warrble
At first, I wasn't sure if it was an amplitude or frequency "warble".
Finally decided it was frequency. A little ragged, but affected both receive and transmit. Not much, only a few htz, but ragged and disconcerting after so many years of faithful service................ since I considder myself a a repairman, what do I do next? 30 or 40 years of "freezemist" and " "heat gun" analysis, I still don't know my way around this Kenwood TS-130. (my first transciever). Replace all electrolytics and see what happens next? HELP! Old Chief Lynn, W7LTQ since 1948 |
Kenwood TS-130 Frequency warrble
coffelt2 wrote:
At first, I wasn't sure if it was an amplitude or frequency "warble". Finally decided it was frequency. A little ragged, but affected both receive and transmit. Not much, only a few htz, but ragged and disconcerting after so many years of faithful service................ since I considder myself a a repairman, what do I do next? 30 or 40 years of "freezemist" and " "heat gun" analysis, I still don't know my way around this Kenwood TS-130. (my first transciever). Replace all electrolytics and see what happens next? Is it warbling at 60 or 120 Hz? If it is, supply rails might be an issue. But I'd first look at every internal oscillator on a scope and see which one is unstable. Don't lock the scope to the input, lock it to line and adjust the sweep by hand until the image on the scope stabilizes. You will see any phase noise readily (assuming the scope timebase has no visible phase noise). One of those oscillators is noisy. If they are _all_ noisy than it's time to look at the supply. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Kenwood TS-130 Frequency warrble
On 14/01/14 09:58, coffelt2 wrote:
At first, I wasn't sure if it was an amplitude or frequency "warble". Finally decided it was frequency. A little ragged, but affected both receive and transmit. Not much, only a few htz, but ragged and disconcerting after so many years of faithful service................ since I considder myself a a repairman, what do I do next? 30 or 40 years of "freezemist" and " "heat gun" analysis, I still don't know my way around this Kenwood TS-130. (my first transciever). Replace all electrolytics and see what happens next? HELP! Old Chief Lynn, W7LTQ since 1948 Scott's suggestion is a good one but I'd also suggest you consider checking that the PLL isn't simply on the limit of lock. It doesn't sound like you've checked the radio over since new and, with the ageing of components etc., it is quite possible things are not as they should be. I've done a quick Google and there are copies of the Service Manual on the internet and Kenwood manuals are pretty good. You should be able to make the adjustments. 73 Brian G8OSN/W8OSN |
Kenwood TS-130 Frequency warrble
"Brian Reay" wrote in message
... Scott's suggestion is a good one but I'd also suggest you consider checking that the PLL isn't simply on the limit of lock. It doesn't sound like you've checked the radio over since new and, with the ageing of components etc., it is quite possible things are not as they should be. I've done a quick Google and there are copies of the Service Manual on the internet and Kenwood manuals are pretty good. You should be able to make the adjustments. 73 Brian M3OSN/G8OSN/W8OSN Well done, Brian! See, you can make a positive and relevant contribution to discussion, without gratuitous and somewhat infantile sneers, in this NG if you really try. Keep up the good work! |
Kenwood TS-130 Frequency warrble
In article , Brian Reay wrote:
Scott's suggestion is a good one but I'd also suggest you consider checking that the PLL isn't simply on the limit of lock. It doesn't sound like you've checked the radio over since new and, with the ageing of components etc., it is quite possible things are not as they should be. I'd bet a nickel that this is precisely what is wrong... but you'll know it when you see the PLL output it on the scope and it's bouncing around! I've done a quick Google and there are copies of the Service Manual on the internet and Kenwood manuals are pretty good. You should be able to make the adjustments. It's conceptually very different than working on an R-390 but to be honest it's a whole lot easier. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Kenwood TS-130 Frequency warrble
On 14/01/14 21:10, Scott Dorsey wrote:
In article , Brian Reay wrote: Scott's suggestion is a good one but I'd also suggest you consider checking that the PLL isn't simply on the limit of lock. It doesn't sound like you've checked the radio over since new and, with the ageing of components etc., it is quite possible things are not as they should be. I'd bet a nickel that this is precisely what is wrong... I've seen it, and fixed it, numerous times. One of these things you see when you've been around a bit. Following the PPL set up procedure normally cures it for another decade or more, I've never had one back again. 73 Brian G8OSN/W8OSN |
Kenwood TS-130 Frequency warrble
On Tue, 14 Jan 2014 15:48:24 -0000, "gareth"
wrote: "Brian Reay" wrote in message ... Scott's suggestion is a good one but I'd also suggest you consider checking that the PLL isn't simply on the limit of lock. It doesn't sound like you've checked the radio over since new and, with the ageing of components etc., it is quite possible things are not as they should be. I've done a quick Google and there are copies of the Service Manual on the internet and Kenwood manuals are pretty good. You should be able to make the adjustments. 73 Brian M3OSN/G8OSN/W8OSN Well done, Brian! See, you can make a positive and relevant contribution to discussion, without gratuitous and somewhat infantile sneers, in this NG if you really try. Keep up the good work! Ok Beanie, now its your turn. -- 73 de Frank Turner-Smith G3VKI - mine's a pint. |
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