[Amps] NXP 65V LDMOS 1K80H-1800W

Catherine James catherine.james at att.net
Sun Dec 24 14:34:04 EST 2017

Can it handle continuous 100% duty cycle on MID?

Sent from Yahoo Mail on Android 
  On Sun, Dec 24, 2017 at 12:50 PM, Paul Baldock<paul at paulbaldock.com> wrote:   SPE say 1.5KW SSB and CW, no limit. Continuous duty modes, should be 
used on the lower 1KW or 500W ranges.

This will by my 6M amp / instant on HF / backup HF amp. I plan to limit it 1KW.

 From the manual :

"Note: ATTENTION: Never stress the amplifier with long periods in 
key-down transmission,
as this can stress the amplifier components. However, sophisticated 
Software avoids
transmitting a continuous signal in the "MAX" condition for long 
periods by switching
to "MID" power.
Note: In SSB, use of high compression is not encouraged as this can 
cause a rapid increase
in the temperature of the amplifier."

"Appears when a continuous signal is transmitted in
"MAX". After 15 sec. the amplifier will switch
automatically to "MID"."

- Paul
At 08:49 AM 12/24/2017, Jim Thomson wrote:
>Date: Sun, 24 Dec 2017 01:01:39 +0000
>From: Bill Turner <dezrat at outlook.com>
>To: Amps group <amps at contesting.com>
>Subject: Re: [Amps] NXP 65V LDMOS 1K80H-1800W
><I checked the website for SPE, looking for duty cycle specs but didn't
><see any. Does anyone know what they are?
><73, Bill W6WRT
>###  Excellent  question.  And ditto with the new Flex...power 
>genius..with its mystery 100%  ICAS rating.
>IMO, 100% ICAS means talk on ssb or cw  all day long.... but dont do 
>something stupid, like a rtty contest.
>##  These SS amps are typ 50% eff at best, so with 1.5 kw out 
>requires 3 kw dc input.
>Dissipation of course is 1.5 kw.    Thats a bunch.  And a huge 
>amount  if running rtty,
>FT8, any other digital mode, or FM etc.
>##  any tube amp running just 60% eff, would only require 2.5 kw dc 
>input...and  dissipation
>is now down to just 1 kw.
>##  On the lower 3 bands,  with the same tube amp on 
>160-80-40,  68-70% eff is readily achievable.
>Now the diss is down even more, to just  706-  643 watts.
>##  helluva big difference between  1500 watts ccs diss on the SS 
>amp..and the  643- 1000 watts
>CCS diss  of the SS amp.
>##  It would require some exquisite  heat sink design to be able to 
>dissipate 1500 watts  CCS of heat.
>This is where the SS amp should be using a  19 inch wide rack mount 
>heat sink, very deep, and very tall,
>like 12 inches or more, and lotsa air on it.    Loads of fins, and 
>very thin fins.
>## that or some elaborate cooling setup, with a liquid cooled heat 
>sink and an external air cooled radiator +
>mating water pump.
>##  ideally the way to manage heat is to generate less of it in the 
>1st place, like through higher eff,  which
>appears is not going to happen any time soon with typ class AB  SS amps.
>##  I would like to see what both these amp manufacturers  have to 
>say about  duty cycle.
>If they are  1.5 kw  ICAS,  I will pass on em for now, not for the 
>$7K price tag.
>Jim  VE7RF
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