Ferrite common mode chokes are very unlikely to have adverse effects on
the electronics, unlike bypass capacitors. (Slow rise times, oscillating
op amps, etc.) And they often ARE effective at reducing RFI.
That said, I have one of those cheap Bryant furnaces with variable speed
blowers, and I've never heard any RFI from it. Nor does 1500 W into a
shunt fed tower on 80 and 160 forty feet away affect it. Unlike the
water heater, which I have to reset after every 160 contest, or I'm in
big trouble.
73,
Scott K9MA
On 2/8/2020 07:25, AA5CT via RFI wrote:
re: " What happened to RF chokes and bypass capacitors, which when
the correct component values and specifications are used (value,
current handling and voltage rating), will work better and cost much
less? "
Fine, if you are the OEM (and can implement those at board level),
not so fine on a new installation where there is a warranty in effect.
Using the ferrites a service tech can see the "minimal intrusion" the
ferrites make into the circuitry of the unit (whether on the AC line side
or the thermostat side.) Getting in there to add circuit components to
a control board is a whole 'nother thing.
de AA5CT
.
.
On Saturday, February 8, 2020, 06:16:12 AM CST, Rob Atkinson
<ranchorobbo@gmail.com> wrote:
First, there's nothing wrong with American Standard as far as I know,
which is a premium brand manufactured in Texas by Ingersol Rand.
Forced air A/C in the home, almost always uses the same air blower
motor that's used by the furnace. If that's the variable speed
component, you can solve everything by getting an AC motor. The
variable DC motors are used by people who obsess over a relatively
minor improvement in efficiency.
Why do hams mindlessly use ferrite on everything, including lines that
only have DC on them? What happened to RF chokes and bypass
capacitors, which when the correct component values and specifications
are used (value, current handling and voltage rating), will work
better and cost much less?
73
Rob
K5UJ
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--
Scott K9MA
k9ma@sdellington.us
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