[Elecraft] An interested link

[David Cutter]

There might be 2 distinct problems:  a) the bandwidth of the signal you 
think you have and b) splatter caused by over-modulating and over-driving.

Starting with a wide-ish signal of say 6 or 7kHz, ie dsb full carrier might 
be ok in uncrowded bands, but add badly adjusted modulation and drive to 
another badly adjusted amplifier (a non-linear linear amplifier) and you've 
got double trouble that can be heard across the world even worse than 
over-driving ssb.  Couple that with the sort of drift those boat-anchors are 
capable of and I can see why they have a bad reputation.  All of which can 
be corrected by proper adjustment which takes more skill and understanding 
not now taught.


David
G3UNA



> Fortunately the K3 is quite good on AM transmit, unlike legacy equipment
> often used. I don't know about elsewhere, but here in the UK there are
> 80m AM nets where some of the stations run original AM gear without any
> additional audio filtering, one was measured at +/- 12 KHz by a fellow
> ham with an SDR receiver. The operator seemed indifferent to the fact
> his transmission was excessively wide and carried on regardless. The guy
> who measured the wide signal used home built AM gear himself, but had a
> multi-pole active filter of a similar specification to that used by
> broadcast stations to achieve their "skyscraper" envelopes as seen on a
> panoramic adapter or SDR receiver.
>
> The UK license has the clause "The bandwidths of emissions should be
> such as to ensure the most efficient utilisation of the spectrum".
>
> 73 Dave, G4AON
> K3/100 #80
>
> Joe, W4TV wrote:
>
> Similarly, AM - except for legacy equipment - should be
> limited to 6 KHz bandwidth. In other words, the maximum
> modulating frequency should be set at 3 KHz - or no more than
> 3200 Hz.
>