[ARC5] HF Converter - feeding mixer with a square wave?

Thu Mar 17 21:16:00 EDT 2022

Bob – 

Can you reference the book that you used during your studies? 73 – Mike 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

848-245-9115

-----Original Message-----
From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of Bob kb8tq
Sent: Thursday, March 17, 2022 9:12 PM
To: Tom Lee <tomlee at ee.stanford.edu>
Cc: ARC-5 <ARC5 at mailman.qth.net>
Subject: Re: [ARC5] HF Converter - feeding mixer with a square wave?

Hi

At least when I took the course in school on this stuff, the basic definition of “linear” was indeed that the output was the input times a constant. Anything other than that was “non-linear”. This is at the root of the conversation about mixers being non-linear. If that *is* you definition of linear then mixers must be non-linear.

Bob

> On Mar 17, 2022, at 9:09 PM, Tom Lee < <mailto:tomlee at ee.stanford.edu> tomlee at ee.stanford.edu> wrote:

> 

> Think about how one actualy uses a multiplier as a mixer, Bob. The input-output relationship of relevance is that between the IF output and the RF input. That is supposed to be linear, right? That is, the output should be a constant times the input, just as you yourself stated as the requirement.

> 

> --Tom

> 

> --

> Prof. Thomas H. Lee

> Allen Ctr., Rm. 205

> 350 Jane Stanford Way

> Stanford University

> Stanford, CA 94305-4070

>  <http://www-smirc.stanford.edu> http://www-smirc.stanford.edu

> 

> On 3/17/2022 17:45, Bob kb8tq wrote:

>> Hi

>> 

>> If you accept the definition that a “linear” circuit *only* produces 

>> the input times some constant ( = the gain ) then anything that 

>> multiplies must be non-linear.

>> 

>> If you look at a different definition, then of course, they can be linear.

>> It’s just a mater of what your base definitions are.

>> 

>> Bob

>> 

>>> On Mar 17, 2022, at 8:13 PM, Tom Lee < <mailto:tomlee at ee.stanford.edu> tomlee at ee.stanford.edu> wrote:

>>> 

>>> (Just to clarify, this was posted in response to Bob Nickels, not to 

>>> Mike St. Angelo -- sorry for the confusion, Mike!)

>>> 

>>> --Tom

>>> 

>>> --

>>> Prof. Thomas H. Lee

>>> Allen Ctr., Rm. 205

>>> 350 Jane Stanford Way

>>> Stanford University

>>> Stanford, CA 94305-4070

>>>  <http://www-smirc.stanford.edu> http://www-smirc.stanford.edu

>>> 

>>> On 3/17/2022 12:16, Tom Lee wrote:

>>>> I wish people would stop repeating the claim that mixers are inherently nonlinear. That’s completely false. It is true that nonlinear things can produce mixing, but that’s a side effect, not an inherent property!

>>>> 

>>>> Good mixers have to be linear. You want the IF output to be proportional to the RF input.

>>>> 

>>>> We treat mixer nonlinearity in much the same way as we treat amplifier nonlinearity. It is an undesirable property and considerable effort is expended to minimize it.

>>>> 

>>>> Tom

>>>> 

>>>> Sent from my iThing; please forgive the typos and brevity

>>>> 

>>>>> On Mar 17, 2022, at 11:39, MICHAEL ST ANGELO < <mailto:mstangelo at comcast.net> mstangelo at comcast.net> wrote:

>>>>> 

>>>>> Bob,

>>>>> 

>>>>> Enjoyed that article and the one about the Si5351 Quadrature oscillator. Have the tried feeding the Si5351 to the SA612 instead of an Epson? It gives the the ability of easily changing frequency.

>>>>> 

>>>>> The SA612 and Si5351, what a pair for experimenters.

>>>>> 

>>>>> Mike N2MS

>>>>> 

>>>>>> On 03/17/2022 1:05 PM Robert Nickels < <mailto:ranickels at gmail.com> ranickels at gmail.com> wrote:

>>>>>> 

>>>>>> 

>>>>>>> On 3/17/2022 11:10 AM, Phillip Carpenter wrote:

>>>>>>> Can you please share the circuit diagram of your universal converter board that you used with the BC-453 receiver?

>>>>>> I've added an article about it to my website: 

>>>>>>  <https://tinyurl.com/mrj7rndd> https://tinyurl.com/mrj7rndd

>>>>>> 

>>>>>> The 4.7uH/100pF values shown work for 40 meters, or calculate 

>>>>>> your own - I use a 10uH fixed inductor and 150-180pf capacitor for 75-80 meters.

>>>>>> 

>>>>>> 73, Bob W9RAN

>>>>>> 

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