[Amps] K8CPA

[Bill L. Fuqua]

I did not get the original email that started this.
Please send me a copy of the email dirctly that started this.

Two comments of my own. I am a great fan of TenTec. I visit there every year. Look at their new products and have attended their hamfest every year except for this year (family illness). 

 However, I will say that I was somewhat disappointed in their new product. In 3 ways:

  1. Power consumption in receive which is much too high for portable work. I have the same complaint with the FT817 and FT100 and IC706MK2. I have all of these three.
I figured Tentec would be cleaver enough to do better.
I would probably still buy one if I could fit it into my  budget.

   2. Their noise blanker is DSP after a narrow crystal filter. This reduces the effectiveness of the noise blanker. Because the impulse noise pulse width is convoluted to a much wider pulse after passing thru a narrow filter. The best noise blankers are implemented where the bandwidth is at least several hundred KHz. This was also why early Drake noise blankers did not work well.

   3. Way to many components. Looks like they took the usual Asian approach in design.
 
   However, taking into account the features vs the above shortcomings, I would probably buy one. But I like battery operation and am looking forward to a lower power version.

Now one other issue. 

The noise blanker comment above is related to what is referred to as ringing and Heisenberg's Uncertainty Principal. This is a mathematical fact.  Unlike theories and laws this is an undisputable fact.  

The product of bandwidth and pulse width can't be less than 1. In this case frequency is in Hertz or cycles per second. 
In quantum mechanics these are expressed as (energy, time)  or
(momentum, position) and and Planks Constant instead of the constant of 1. 
Sometimes other factors appear depending on the space used. Physicist like using K-space at times or frequency in radians per second which throws in a factor of 2*PI as well.  But all these  expressions go back to  the relationship of bandwidth and pulse width. 
That is to say if you have a filter passing a tone burst ( a dit) that is 0.1 second long then the filter will have to have at least 10 Hz band width to pass it.  If you have a shorter burst than 0.1 seconds long then the filter will stretch it to 1 second (ringing). 
     For the same reason  a noise blanker needs to be preceded with a wide bandpass filter so that  the short burst may be detected and eliminated (blanked) in such a way that very tiny bit of time where the signal is not passed is not detectable after narrower filtering and detection.  

Take a look at this web page:
http://www.mathpages.com/home/kmath488/kmath488.htm and note equation 2.

The method of filtering does not matter. It is the bandwidth. 

merry Christmas and 
73
Bill wa4lav