I guess I'm fortunate, I've had Astrons running 24/7 for decades without
any failure. A 20A powers my repeater (IRLP node, 25 watt), a 35A power
the Elecraft products and I just installed a 60A rack mount to replace
them both (all are adjusted to 14.2 for spectral purity plus I can
charge LiFePo4 too).
Rick NK7I
On 4/17/2020 12:49 PM, Bob McGraw K4TAX wrote:
I have always been taught and thus have a concern when power supplies
of excessive capacity are used for any type of service. If the wiring,
in this case, between the power supply and the radio is #12 or #14 of
any length typically supplied by radio companies, should a short occur
in the power cable, it is likely the power supply will deliver full
current. That will quickly melt the insulation on the power cable and
could cause a fire before the power supply goes into current limit.
Now at the same time, each power cable could be fused at the supply to
limit the amount of current the supply can drive into the cable. I
have to say I don't like this idea as the in-line fuse adds a
significant amount of resistance and will impact the stability or
degree of regulation of the voltage at the radio under a dynamic
changing load such as SSB or CW.
All of this is no different than when one uses a battery for their
radio. In auto installations, for that reason, it is highly
recommended that a fuse or circuit breaker be located at or very near
the battery. Same applies here where the supply is capable of
delivering very high amperage. I realize power supplies of this
nature have over current protection. However, 70 amps through #14
wire will will produce lots of heat and smoke amazingly fast.
The correct solution is not so simple in one sense of the word. The
better solution is to use properly rated supplies for the required
load. For that very reason, I have two 30 amp CCS rated supplies on
my desk. One feeds the Elecraft 100 watt transceiver while the other
feeds the Tentec Eagle 100 watt transceiver.
All of my supplies have both voltage and current meters and they are
in a position I can see them when I turn them on. With supplies which
do not have meters, when one turns them on, you never know in advance
and get what they deliver. In my case, I observe the meters BEFORE
turning on a radio. On more than one occasion this has saved a radio
due to a power supply regulation failure. Dumping 24 to 32 volts
into a $3000 radios is not very pretty. Oh yes, the supplies do have
OVP, Over Voltage Protection, but I've seen this fail as well and I've
repaired several supplies where this did fail. And one doesn't know
it has failed until the voltage goes to maximum value. Its too late
then to find out the OVP circuit has failed. A meter would have
prevented radio and accessory equipment damage.
73
Bob, K4TAX
On 4/17/2020 12:28 PM, j...@kk9a.com wrote:
I also use an Astron RS-70 for my K3Ss. Like you, mine was not
purchased for this purpose. It is under my desk so the physical size
is not an issue and I have no worries about overloading it.
John KK9A
Barry w2up at comcast.net
I got a kick out of "big hulking supply," too. I have an RS-70 on my
K3. It
used to power a lot more stuff, but since I downsized my station, it
loafs
along. Definitely overkill, but it sits under the desk, out of the
way, so
why not? Oh yeah, my keyer's on it, too, and still doesn't get warm,
even
at QRQ :-)
Barry W2UP
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