I would never pilot an airplane unless I performed a proper and complete
ground inspection while using a check-list.
I would never buy a power supply unless I perfromed a proper evaluation but
first knowing the needed power requirements.
73
Bob, K4TAX
----- Original Message -----
From: "Ken Brown" <ken.d.brown@hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, January 20, 2014 8:19 PM
Subject: Re: [TenTec] Power supply types
They are both commonly available and they can both be used to power
typical HF transceivers. I think it is a reasonable comparison to make.
Here is another question: What kind of power supply did you first see
reviews in QST in which the subject of RF noise generation was even
mentioned?
Yes, switched mode power supplies CAN be made that do not generate (and
radiate) RF noise. And switched mode power supplies are generally more
energy efficient.:
How about we state the question this way:
Suppose you're on vacation and you brought your mobile rig along with you,
which runs on 12 VDC. You planned on only operating from your vehicle, so
you did not bring a power supply for use from 120 VAC. You are offered an
opportunity to stay for free in a nice vacation rental cabin for a week.
The cabin has all the conveniences, including grid power. There are tall
trees and you have a spool of skinny copper wire and an antenna tuner in
your vehicle. You think it will be a great opportunity to get on the air
from a remote location, with hopefully not a lot of RF noise. Before you
head up into the mountains to the go to the cabin you see a store which
sells two kinds of power supplies that have the right voltage and current
rating to power your rig. One of the power supplies is very lightweight
and the label say it is super efficient and uses switching mode
technology. The other power supply is heavier, and you can see it has a
laminated iron core transformer and a big electrolytic capacitor in it.
The prices of the two power supplies are identical and they both appear to
be well constructed. You cannot find any other data about these power
supplies. The drive to the cabin is long, and you don't intend to drive
back to town until you have finished your stay at the cabin. If you buy
both power supplies, you won't have enough money left to buy the wrist
rocket slingshot you intend to use to send the skinny wire up into the
tall trees.
Which power supply would you buy?
DE N6KB
On 1/20/2014 3:41 PM, Kim Elmore wrote:
This is an apples vs pecans question.
Better-stated questions:
What's the probability that a properly-designed and engineered linear
power supply will radiate RF noise of sufficient amplitude to be
bothersome?
What's the probability that a properly-designed and engineered switching
power supply will radiate RF noise of sufficient amplitude to be
bothersome?
Answer: unknown. likely small but equal.
Kim N5OP
On 1/20/2014 7:13 PM, Ken Brown wrote:
What is the probability that a transformer/rectifier/capacitor
filter/linear regulated power supply will generate and radiate (through
AC power input or DC power output leads) RF noise of sufficient
amplitude to be bothersome? That probability may not be zero.
What is that probability that a switched mode regulated power supply
will be not "properly engineered" and generate and radiate RF noise of
sufficient amplitude to be bothersome?
How do those two probabilities compare?
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