[Elecraft] Electrolytic Capacitor failure

[Rick Bates, NK7I]

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, john at 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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