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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 1:19 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Westminster, CO, USA
Greetings, Wizards!<P>I just thought I'd come to my favorite source of strange knowledge, the Antique Radio Forum, and ask if any of you radio geniuses know what a "Neutrodyne" is? I assume it refers to some sort of unique circuit configuration, but how does it differ from, say, a superheterodyne?<P>Many thanks!<P>------------------<BR>Win Kindel


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 1:30 am 
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Location: Maryland 20709, USA
Neutrodyne is the tradename of a patented type of TRF (Tune Radio Frequency) receiver from the early 1920's.<P>The receiver was available in kit form, in four- and five-tube models. There's also a mention of a three-tube version in the brochure, but I'm not sure if it used the same circuitry. I'll look at it this evening.<P>When triodes are used as an amplifier in a grounded-cathode configuration, they tend to oscillate due to the signal fed back through the grid-to-plate capacitance. In order to prevent oscillation, each stage must be "neutralized" by coupling an out-of-phase signal back to the grid circuit from the output. There are various ways of doing this.<P>I'll post some more detailed information tomorrow when I have the schematic in front of me.<P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 2:02 am 
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Location: Pocasset, Cape Cod, MA
It was a particular form of neutralization patented by Alan Hazeltine and licensed to a small group of manufacturers.<P>Books have been written on it and we could only cover the high points here.<P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 8:05 am 
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Follow-up...<P>The four-tube FADA Neutrodyne was an odd reflex design, which used the second RF amplifier tube also as the first AF amplifier stage.<P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 8:21 am 
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Location: Arvada, Co., USA
Check in the ARCHIVE and you will find a scan of a 1923 book from FADA that I sent in on how to build the Hazeltine Neutrodyne. <P>Rich<P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 10:34 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Albuquerque, NM 87123
For a time, Philco used neutrodyne (their invention) and tried to one-up the competition that also used it, by marketing neutrodyne-plus (with super-power), claiming that an antenna was not needed. The use of the word 'super' was greatly over-used even then.<BR>In fine print, they say that with an aerial, you will get 'remarkable distance range'. They also claimed that with neutrodyne-plus, you didn't get any howls, squeals or oscillations. BS was alive and well 80 years ago, just like today. <P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sat 08, 2005 3:51 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Pocasset, Cape Cod, MA
Hazeltine's Neutrodyne scheme worked, didn't infringe on RCA's patents, and had high "name recognition" among the public (witness all the other "-dynes" that appeared later). So it was a valuable license, even by the late 1920s, when Philco bought its license from Murdock which had fallen on hard times.<P>Back in mid-1922 Wireless Specialty tried to put other crystal-set makers out of business by suing them for infringing various patents it owned. This prompted a number of them to band together under the Independent Radio Manufacturers, Inc. umbrella, and they were able to stop WSA from publishing threatening ads. They happened to select the same law firm that was handling Alan Hazeltine's patent application, and when they heard about it they all signed up for licenses. Fourteen companies eventually joined. Fada was the first to get into production, and for a couple of years the Neutrodyne goose laid golden eggs. Here's a list (from vol.1, Radio Manufacturers of the 1920s) of licensees:<P>Amrad (later bought by Crosley)<BR>Fada<BR>Carloyd (Malone-Lemmon)<BR>Eagle<BR>Freed-Eisemann<BR>Garod<BR>RSL (Radio Service Labs, bought by Gilfillan)<BR>Howard<BR>BMI (Broadcast Mfrs Inc, bought by King)<BR>Murdock (bought by Philco)<BR>Stromberg-Carlson<BR>Thompson<BR>Ware<BR>Workrite<P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sun 29, 2006 2:24 am 
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Location: Pocasset, Cape Cod, MA
If it has three tuning dials with pointers, it's probably a model 25 or 30 sold in the fall of 1925. King was affiliated with Sears, Roebuck.<P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Sun 29, 2006 4:58 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 248
Location: Liberty, Texas USA
Grebe’s Synchrophase also used the Neutrodyne principle. Although it was not legal, did Grebe ever use the Neutrodyne license that it was taken out after the court ruled in Hazeltine’s favor?<P>------------------<BR>What we do today is the continuing history of radio. <P>br


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Mon 30, 2006 9:05 am 
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Location: ID 83301
This is what the vet does to your cat so it does not have babys<P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Mon 30, 2006 1:12 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Malone, New York USA
Dennis Daly wrote:
<font>quote:</font><HR>Originally posted by Johnnysan:<BR><B>For a time, Philco used neutrodyne (their invention) and tried <BR><snipped> <P>BS was alive and well 80 years ago, just like today. <P></B><HR>
<P> Philco?.."(their invention)"<BR> I thought it was Hazeltine's alone?<BR> Just a slip?<P> Den<P><P>------------------<BR>


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 Post subject: What is a "Neutrodyne"?
PostPosted: Jan Mon 30, 2006 3:39 pm 
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Location: Pocasset, Cape Cod, MA
<B>>>did Grebe ever use the Neutrodyne license</B><P>Probably not; whether Grebe paid up for past infringement I don't know. I believe the Hazeltine licenses had an annual royalty payment, so some money would have changed hands.<P>------------------<BR>


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