[Amps] Ten Tec Herc II (model 420) thermal rating TSPA

m.ford k1ern at direcway.com
Mon Jan 23 14:05:13 EST 2006


    I have used a model 420 for over ten years now. I purchased
it new and was advised by the salesman to just use a car battery
and a charger. Batteries? Don't bother. Run it with a RS-70 and
keep the fused leads big and short. Replace the RS-70 filter caps
with something other than the marginally inadequate voltage
rating of the oem.

    The Hercules cooling fan is woefuly inadequate. I would do
something about that if I were to operate anything other than cw
or ssb.

Mike k1ern



----- Original Message ----- 
From: "John T. M. Lyles" <jtml at lanl.gov>
To: <amps at contesting.com>
Sent: Monday, January 23, 2006 12:39 PM
Subject: [Amps] Ten Tec Herc II (model 420) thermal rating TSPA


>I mistakenly used the term CW here which, among hams, means CW morse, 
> and in RF power engineering terminology means key down 100% operation 
> for  a long time - as opposed to pulsed operation.
> 
> Yes, the Herc II is rated 550 (I was incorrect stating 500) watts CW, 
> with 50% DF and max key down time of 15 minutes. That won't be 
> adequate for 24/7 operation of key down in continuous carrier 
> operation, so I think it might be good for 250 watts. We will test it 
> and see where the semiconductors become unsoldered -- hihi. Maybe I 
> can force cool it better. I wonder if its the RF board/combiner or 
> that black box power supply from Ten Tec that cannot handle the heat?
> 
> 73
> John
> K5PRO
> 
>>According to the manual, the 420 (Herc II) is rated 550 watts output CW,
>>RTTY, and SSB, 1 kW input; SSB is rated for continuous operation, CW/RTTY
>>is rated for a 50% duty cycle with maximum continuous key-down of 15
>>minutes. Efficiency and drive required vary a bit from one band to another.
>>
>>>From conversations on various email lists, I have learned that many owners
>>of the Herc II use it with some P/S other than the TenTec (which they say
>>is rated 100A, and designed to run both the amp and the exciter at 100w).
>>One popular configuration is a deep-charge battery with a suitable float
>>charger. Another is a pair of Astron 70A units (which is what I am using).
>>FWIW, it should run just fine on SSB on one of the Astron 70A supplies.
>>Because I mostly work CW, I use two.
>>
>>Jim Brown  K9YC
> _______________________________________________



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