Re: Harmonics

Bill Cromwell


As for me I am going the external lowpass filter route until this problem is tamed internally. But one question I must ask about operating the radio as-is. Of the thousands of units in circulation - and presumably on the air - how many hams have been cited by their regulatory agencies? 1000? 100? 10? 1? 0? Enquiring minds want to know.

Once again..I will be using external low pass filters at the BNC connector on the back of my uBit. The micro controller software in the Raduino cannot change those for me. Tuners and antennas beyond the filters. Tuners only to show the filters their design 50 ohm load. I don't want to be the first one cited for this. Nor the last.

When one of my daughters married Dr Murphy I though I would be given some slack on Murphy's Law because of being family. Instead, I get more than my share <wink>.


Bill KU8H

On 08/10/2018 09:52 AM, Jack Purdum via Groups.Io wrote:

I realize there are issues and, like everyone else who can fog a mirror,
I want it solved. However, until a viable solution is found, do I stay
off the air? What's the purpose of the spec in the first place? It's to
make sure that a transmitter does not generate signals other than the
fundamental frequency above certain specifications (i.e., strength). But
why? It's done to ensure that my signal does not degrade someone else's
signal on some harmonic frequency. If you, or anyone else, cannot detect
my harmonic signal outside my back yard, I may fail the precise specs of
the law, but am still within the intent of the law.

In your own words: "...if one causes interference..." implies that
someone is impacted by my transmission. If my harmonics are in the noise
level, am I causing interference? Legally, with measures at the source,
yes. To the rest of the world, no. For my stock µBITX, I'm legal on 20M
and above. On 40M, I'm 1dB out of spec. On 80M, I'm 3dB out of spec. I
don't use 80M, other than contests, so that's really not a problem for
me. 40M, however, is my favorite band. Not good.

I'm familiar with the word "denial" and I don't think you should imply
that's what I'm doing. I'm not. I realize there's a problem, but
unfortunately, I don't have the skill set to solve the problem. Your
solution is for me to stay off 80M and 40M until you RF geniuses figure
out a cost-effective solution. So why are you wasting your time bitching
a me? Start pushing a pencil and show me the solution.

In the meantime, I promise not to use 80M...I'm pretty busy right now
anyway, so I don't have much time for operating. However, if you hear my
40M harmonic, let me know and I'll cease operation immediately.

Jack, W8TEE

On Friday, August 10, 2018, 9:20:25 AM EDT, ajparent1/KB1GMX
<kb1gmx@...> wrote:

No. Camp one is it is and it has known problems what it is make your
own choice.
There are issues most can be solved.

The other is a decision to deny, ignore, avoid, and continue. The
English word is denial.

To the Engineer and especially computers engineering its game over as 1
(true) is not 0 (false).

Its a hard reality and if one causes interference they are responsible
for ceasing and fixing.
On that basis I can only give facts after that it is a risk based choice.

bark less - wag more

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