[AMRadio] Smoothing Choke


Larry Taft ltaft at charter.net
Thu May 4 13:06:52 EDT 2006


Let me clear my perfectly description make!

Collins:
                            10 hy           10 hy
     Rectifier ------choke-------choke----|----HV out
                        |---cap---|                      |        
                             0.08uf                      cap  8 uf
                                                              |
                                                            ///  


Larry Taft wrote:
> Typical values for a Gates BC-1G 1 KW broadcast transmitter 2500 VDC 
> supply are 5-15 hy at 1 amp swinging choke with 8 uf filter cap.  The 
> load is 500 ma continuous for the class C final ( 2 833s in parallel) 
> plus another 500 ma variable for the class B modulator ( 2 833s in 
> push-pull).   The audio frequency response  is speced at 30 to 12,000 
> cycles per second.  The broadcast people used a single supply with the 
> final acting as a fixed minimum load to get around the filter 
> resonance problem at low frequencies.
>
> Collins also used a cap across a choke for parallel resonance.  For 
> the 20V3 there is a 10 hy choke with a 0.08 uf cap across it in 
> parallel to a second 10 hy choke (no cap) to an 8 uf cap to ground.  
> Again, the final is a fixed load for the single supply.  Tubes are 
> 4-400s. Audio speced at 50 to 10,000 cycles per second.
>
> Old technology.  Still good as long as the limits are understood.
>
> Larry  K2LT
>
> Jim candela wrote:
>> Rick,
>>
>>    I understand your feel for the nostalgia, and passion for pursuing 
>> it.
>> All of us more or less on this group have some common ground here.
>>   
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