[ARC5] Product detectors - the name.

[Bruce Long]

BillI have a book with the title "Engineering in the Mind's Eye"  It was an anthropology PhD dealing with the key importance of visualization skills in engineering.
The author makes the point and provides numinous examples that it is difficult or impossible to make an accurate drawing of a machine if you do not understand how that machine works.  This is true even if you  have the original object at hand when you attempt the drawing.  

Form follows function but even an artistically trained eye fails to see the form if they lack an elemental understanding of the function.
At the university I went back into the stacks to look up a very early copy of QST magazine circa 1917 or so which had a hookup drawing- the term schematic had not been yet applied to electrical drawings- of what was clearly a full featured parametric amplifier using a galena cat whisker as the semi-conductor device

bruce
      From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
 To: K5MYJ <macklinbob at gmail.com>; Dennis Monticelli <dennis.monticelli at gmail.com>; Kenneth G. Gordon <kgordon2006 at frontier.com> 
Cc: ARC-5 Maillist <Arc5 at mailman.qth.net>
 Sent: Friday, May 12, 2017 3:29 AM
 Subject: Re: [ARC5] Product detectors - the name.
   
#yiv3341653503 #yiv3341653503 -- P {margin-top:0;margin-bottom:0;}#yiv3341653503 
Marconi developed a balanced crystal detector using two crystals, a BFO which was a buzzer and a high Q tank circuit, pots and capacitors to balance out the diode capacitance and forward resistance.  Most of the circuits I have found are wrong. Some simplified incorrectly by leaving out the buzzer-tank circuit thing that it is simply a tuning aid and others that are almost right that reverse on diode. The only correct schematics are found in the patent which I can't seem to be able to find just now.
73Bill wa4lav

From: ARC5 <arc5-bounces at mailman.qth.net> on behalf of K5MYJ <macklinbob at gmail.com>
Sent: Thursday, May 11, 2017 9:49 PM
To: Dennis Monticelli; Kenneth G. Gordon
Cc: ARC-5 Maillist
Subject: Re: [ARC5] Product detectors - the name. This page say the 75A-4 was manufactured in 1955:http://www.rigpix.com/collins/75a4.htm
| RigPix Database - Collins/Rockwell - 75A-4www.rigpix.comType: HF receiver: Frequency range: 10-160 m: Mode: AM/SSB/CW: Sensitivity: N/A: Selectivity: N/A: Image rejection: N/A: Voltage: Mains: Current drain:? Impedance:? ohms |

 The National NC-300 (1955) and NC-303 (1958) have what appears to be a product detector (6BE6). The first grid is the LO, and the third grid is the IF input. The plate of this tube is the detector output. Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- From: Dennis Monticelli To: Kenneth G. Gordon Cc: K5MYJ ; ARC-5 MaillistSent: Thursday, May 11, 2017 3:53 PMSubject: Re: [ARC5] Product detectors - the name.
According to Osterman's book, the 75A-4 was introduced in 1958 and the NC-109 was introduced in 1957.
Dennis AE6C
On Thu, May 11, 2017 at 3:03 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:

On 11 May 2017 at 14:27, K5MYJ wrote:

> I just checked the manuals for the Collins 75A-3 and 75A-4.
>  
> The 75A-3 was sold as an AM/CW/FM receiver. The 75A-4 was sold as an AM/SSB/CW receiver.
>  
> The 75A-3 did not have what we now call a product detector.
>  
> The 75A-4 had both diode(AM) and product(SSB/CW) detectors.
>  
> To me the 75A-4 is the first receiver I know of to be designed for SSB.

Did that pre-date the National NC-109?

Ken W7EKB

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