[Heathkit] SB200 inrush

[jeremy-ca]

So lets see now. The Heath engineers designed surge protection into the 
transformer. After 40 years failures are nil.

So you want to add 8 components consisting of 2 relays, two overstressed 
resistors, 2 import electrolytics, a diode and another small resistor to 
"possibly" fix a problem that doesnt exist. That sure makes a lot of sense.

While some brands of amps could benefit from inrush protection the SB200 and 
220 series certainly are not among them.

Carl
KM1H





----- Original Message ----- 
From: "C E" <catman351 at yahoo.com>
To: <heathkit at mailman.qth.net>; <RMcGraw at Blomand.Net>
Sent: Thursday, May 03, 2007 3:08 PM
Subject: [Heathkit] SB200 inrush


> Just as a matter of practice, if I can prevent putting
> additional stress on any component to last longer,
> that's good enough for me to preserve my electronics.
>
> You can say the same for any mechanical device that is
> constantly battered. If you can stretch the
> mean-time-between failure rates even more, I see no
> reason not to do so.
>
> Cal, N6KYR/8
>>
>> Inrush protection is typically required where the
>> current rating of a
>> transformer is in the 2X or greater value of the
>> operating current.  Heath
>> did not over-design these amps in that manner.  Thus
>> the current rating or
>> maximum current available at startup is will within
>> safe limits of the tubes
>> and transformers.
>>
>> I think it having worked for some 30 to 40+ years
>> without mods, it is likely
>> good for anther 30 to 40 years without mods.
>>
>> I've never found solid technical reasons for inrush
>> current limiting.
>>
>> 73
>> Bob, K4TAX
>>
>>
>> >
>> > But I do disagree on the current inrush protection
>> > comment. I highly suggest adding this item into
>> your
>> > amplifier. It is another potential unit to fail
>> but
>> > the way I take a look at it is that you can have a
>> > $1.00 part to fail or a $100 or more part (i.e.
>> the
>> > power transformer) fail. I think you see the
>> economics
>> > in this. Besides, why needlessly hammer the power
>> > transformer with those annoying inrush 'thuds'?
>> >
>>
>>
>>
>>
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>> End of Heathkit Digest, Vol 40, Issue 3
>> ***************************************
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>
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