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[AMPS] Step Start for Ameritron AL-80A

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Subject: [AMPS] Step Start for Ameritron AL-80A
From: (Steve Thompson)
Date: Thu, 19 Mar 1998 07:26:48 +0000
In message <19980317111636.AAE724@[]>, Rich Measures
<> writes
 ..........  Fuses for a TL-922 go for $15 each from Kenwood.  7w 
>resistors go for around $1.50 each.  

I'm not familiar with commercial equipment. Even allowing for dealer
rip-off, that must be one heck of a fuse.

>>>>I guess it's more difficult with a single transformer as you need
>>>>to let the auxilliary supplies build up to operate the relay.
>>>-  Two or more transformers act like a single transformer when the 
>>>primaries are in parallel. 
>>Indeed - I was thinking of the difference between a commercial amp
>>one transformer for all supplies and home brew system where the
>>auxilliary supplies are often separate.
>There is virtually no difference between the values needed for 
>stepstarting a single transformer and stepstarting two transformers, 
>providing that the total VA ratings are similar.  

Sorry, we've been at cross purposes. My original point was thinking of
where the relay supplies are separately switched and not fed through the

>>>>Having suffered once, I now use a fixed timer which gives a few seconds
>>>>delay - if there's a fault then the line fuse blows.
>>>A fixed timer changes only the capital investment. 
>>True, but it's only pennies.
>A fixed timer costs more than the stepstart circuit in Figure 1, which 
>uses the existing hv filter as the timing capacitor.  

Agreed, but given the cost of what the soft start circuit feeds, the
difference in cost is insignificant.


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