In a VHF contest -on 6 meters - I was getting bursts of wide trashy noise -
pulsing like a drum beat .
Seemed to be peaking north of me . So I went out with my ICOM R10 hand held rx
and just the rubber duck ant --
As soon as I got to alley I could hear bass notes pulsing at same rate as the
RF noise . The neighbors outside
audio system was oscillating on 6 meters (and who knows where else) in sync
with the bass notes !!!!
On 15 meters - It was even worse even some of the trash during the melody
phrases.
Fortunately I think it must have destroyed itself -
So you probably need to add what happens when the amp starts to clip as well as
various non resistive loads
to decide if the amp is "stable"
I spent over 35 years doing solid state RF PAs - 90 percent of the work was
making them stable under
every conceivable condition. Now "audio" devices have higher Ft than a lot of
the "RF" devices I had
when I retired in1998.
Hank K7HP
Date: Mon, 5 Oct 2020 14:07:53 +0000
From: "Cianciolo, Paul, W1VLF" <pcianciolo@arrl.org>
To: Bert <balmemo@sympatico.ca>, "rfi@contesting.com"
<rfi@contesting.com>
Subject: Re: [RFI] Speaking of audio amplifiers... an interesting case
Message-ID:
<BL0PR16MB252928E4DACE6B061C56A9F9B00C0@BL0PR16MB2529.namprd16.prod.outlook.com>
Content-Type: text/plain; charset="utf-8"
Bert,
Not really even 3 feet of wire failed muster.
With a resistor as a load it did fine.
Which was how I originally tested it.
Another interesting fact was you could "tune" where you wanted the harmonics to
be the strongest by varying the length of the speaker/power supply leads.
73,
Paul Cianciolo, W1VLF
ARRL EMC?Engineer
ARRL - The national association for Amateur Radio?
225 Main Street, Newington, CT 06111-1400 USA
Telephone: (860) 594-0392
FAX: (860) 594-0259
Email: w1vlf@arrl.org
World Wide Web: www.arrl.org
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|