[1000mp] Re: 1000mp digest, Vol 1 #224 - 11 msgs

[Mike]

Tom, thanks SO much for the interesting & informative reply.
I suspect most modern dealers aren't too bothered about design errors, as
long as sales are good!
Have you heard about any modification or adjustment that might cure the
'blip'?
73 de Mike, ZL1MH

----- Original Message ----- 
From: <1000mp-request@mailman.qth.net>
To: <1000mp@mailman.qth.net>
Sent: Sunday, June 09, 2002 4:01 AM
Subject: 1000mp digest, Vol 1 #224 - 11 msgs


> --__--__--
> 
> Message: 8
> From: "Tom Rauch" <
> Date: Sat, 8 Jun 2002 05:58:35 -0400
> Subject: Re: [1000mp] MkV SWR/ALC readings.
> Reply-To: 1000mp@mailman.qth.net
> 
> 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 
> 
> 
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