[Elecraft] IMD and supply voltage

Bob McGraw - K4TAX rmcgraw at blomand.net
Thu Oct 29 16:48:21 EDT 2015


I agree Jim.  Many hams do not understand what IMD values mean and how 
it affects other signals on the bands.  To wit, the "on frequency" 
signal is not affected, the IMD is not heard on frequency, so it is of 
little concern to the operator as they are only concerned about getting 
a big signal report.  However, a transmitter and/or amplifier spewing 
garbage across the entire band affects all of us.  We fight noise and 
QRM most aggressively with receivers.  Some of this noise we must deal 
with is IMD from adjacent stations often some 5 kHz to 20 kHz or more.  
The ones I simply detest are the operators that say "my station sounds 
great" not realizing the amount of garbage he's spewing up and down the 
band for the rest of use to deal with.

Signal reports heard being given today are largely "ego reports" and are 
of little to no value.  When was the last time you heard a report 
indicating ones audio is distorted, or sounds like the transmitter has a 
bit of FM, or there's buck shot heard 10 kHz away, or there's a noise, 
humm or a buzz on your signal?   Nope, we don't want to offend anyone 
and thus seemingly just roll out a meaningless, non constructive 
report.  I suppose to many of us have forgotten what we learned; "if you 
can't say something nice, then don't say anything at all".

We talk about the level of electronic noise which is heard today as 
opposed to what we heard 20 or so years ago.  Well, the IMD component is 
part of that electronic noise.

Yes I would agree the technology is available and that company's should 
or could design radios to attain at least a 10 dB improvement in IMD 
numbers.  Yes, the ARRL does represent a majority of the hams in the US 
area.  I would certainly like to see them petition the FCC for improved 
specs in this regard.

73
Bob, K4TAX

On 10/29/2015 12:37 PM, jim wrote:
> How about 80 watts instead.
>
> Won't make a noticeable difference on the receive end.
>
> Even better, get rid of all the Yaesu and Icom "Clackers" with their VERY
> poor CW performance.  You can have the best class A amplifier in the world,
> but garbage in will always equal garbage out.
>
> I am ashamed at our "leaders" at the ARRL for not petitioning the FCC for
> better specs.  The technology is there, they all use it in their business
> radios that have a better spec.
>
> Oh, I forgot, follow the money and take the advertising monies from these
> clackers
>
> Jim
> W6AIM




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