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Subject: [AMPS] 4-1000 IDLING CURRENT
From: (Rich Measures)
Date: Mon, 30 Mar 98 04:44:59 -0800
>>>My Home brew 4-1000 amplifier works great except for on thing.  The power 
>>>seems low.  I believe it may have something to do with the low idling 
>>>Plate voltage is 4,600 VDC and idling current is about 80 ma.  
>>Zero signal anode current - a.k.a. idling current - should be about 20% 
>>of max.., or around 150mA.  
>Accoring to Eimac specs, the idling current should be 110 mA at 5000 V, 
>so I think 150 is too high at 4600.
110 mA at 5000 V is roughly half of the diss. rating, and it makes the 
8166 more linear and easier to drive.  
>>>The max plate
>>>current I can load it to is 450 - 500 ma.  At 4,200 VDC under load and 450 
>>>plate current, gets 1,450 watts out with about 130 watts drive.  
>>Normal drive power is around 190w with such low anode V.  If you want to 
>>make an 8166/4-1000A play well with low drive levels, you need 6 to 7kV 
>>on the anode. 
>I wouldn't put more than 6 kV on the anode of a 4-1000A.  6 KV is the 
>maximum that Eimac specs, or am I missing something here?
The 6000v rating is for A-0 continuous, dead carrier.  The AM rating is 
5kv with 100% modulation, which means 10,000v peaks.  8166s reportedly do 
ok on SSB with 7kv.  However, more v means more gain, and more gain 
increases the risk of regeneration above the grounded grid's self 
resonant freq.  


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

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