[AMPS] Step Start for Ameritron AL-80A

[Rich Measures]

>I have an Ameritron AL-80A which makes the loud CLUNK sound when the
>power switch is engaged.  I assume that step-start/current inrush
>protection would prevent this.  My questions for the list:
>
>1.  What type of step-start do you suggest for the AL-80A?  Your ideas
>are welcome.  
>
>2.  I ran across a step-start circuit for the Heath SB-1000 (which I
>believe is a clone of the AL-80A) in the June 1996 QST (Hints & Kinks,
>page 69) designed by W3IRZ.  He uses a large 25-watt resistor (for
>240-volt operation) and a DPDT relay with a 120-VAC coil.  Has any one
>tried this?  

AC coil relays tend to buzz.  

> Has any one improved the circuit?  This looks pretty simple
>even for me and the parts seem to be readily available.
>
The circuit shown in Figure 1 at:  
www.vcnet.com/measures
is simple, uses a pair of inrush resistors so that it works on 120v and 
240v, and can be powered by the AL-80's 12vdc (?) supply.  The timing 
element is the hv supply filter capacitors.  When the caps. are 2/3 
charged, the relay closes.  For an AL-80 a pair of 7w c. 25 ohm resistors 
should work satisfactorily.  
later, Jack

cheers
Rich...

R. L. Measures, 805-386-3734, AG6K   


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