[1000mp] MkV SWR/ALC readings.

[Tom Rauch]

Hi Mike,

> I posted this to the list some months ago, but received only 1 reply
> (from someone with the same problem). When using my Autek WM1
> SWR/POWER meter, set to 'peak', and with my MkV RF output set to
> anywhere within the range 30 - 170W, there is a marked 'blip' on the
> WM1 SWR meter with each 'make' of my key - this 'blip' does not show
> on the MkV meter, even with the peak-hold (menu 4-0 ) set to maximum.

That "blip" is common, but it is a design error at fault. So if your 
dealer considers it "normal", it must be he considers design errors 
normal.

The cause is simple. The rise time of the envelope is faster than the 
ALC system response to increasing power, and the rig outputs a more-
than-full power output transient momentarily until the ALC has a 
chance to catch up. Some rigs (and systems) output this transient 
while relays are switching, and it causes a high SWR reading either 
from a small arc creating broadband RF energy or, if the meter is 
before the switching connection, you might see a "hot-switch" 
condition cause a momentary SWR peak. 

These problems show only on very fast meters with long hold-time. The 
meter in my Ameritron ATR-30 and my sample-and-hold Bird Digital 
power meter will clearly show them. 

The FT1000D is totally free from this problem, while rigs like an 
IC775DSP I had would bounce up to almost 300 watts when set for 
twenty watts output!! It is common, but not what I'd call normal. It 
can tear up an amplifier, and aggravates the already annoying 
keyclicks and thumps from some rigs. It is especially hard on 
amplifier band switchs and tank components if it happens while relays 
are transferring, and can work on the grids of sensitive tubes or 
blow FET's out of PA's.

73, Tom W8JI
W8JI@contesting.com