[Amps] New 2 PA design

[Baruch Zilbershatz]

I am still unable to find out what is the price for the device.

I have finished my 2xBLF574 board with all the bias circuitry and thermal sensors.

I will make the board tomorrow and begin to populate .

   I am using 3oz.Cu on g-10,FR4 material.

I will see how it comes out.

 

Baruch Zilbershatz 

Nitzanay-Oz 118 

Nitzanay -Oz 

42836

ISRAEL 

phone: (+)972-052 8753838

 

From: Paul Decker [mailto:kg7hf at comcast.net] 
Sent: Sunday, October 17, 2010 7:46 PM
To: Baruch Zilbershatz
Cc: Amps at contesting.com
Subject: Re: [Amps] New 2 PA design

 

The DL amp does look good.   The 2.5k has the same type of bars and screw clamps as well.  I used the same ones as well.

 

Paul


----- Original Message -----
From: "Baruch Zilbershatz" <4z4rb at bezeqint.net>
To: "Paul Decker" <kg7hf at comcast.net>
Cc: Amps at contesting.com
Sent: Sunday, October 17, 2010 1:37:41 AM
Subject: RE: [Amps] New 2 PA design

The DL guys that built that gizmo had it clamped with copper bars and screws both sides to a copper heat sink .looks great.
One guy made his own Al heatsink from folded Al strips and on top of it had a copper heat spreader

Baruch Zilbershatz 
Nitzanay-Oz 118 
Nitzanay -Oz 
42836
ISRAEL 
phone: (+)972-052 8753838

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On Behalf Of Paul Decker
Sent: Sunday, October 17, 2010 12:20 AM
To: amps at contesting.com
Subject: Re: [Amps] New 2 PA design



Hi Dan, 



You are right, heat and control are the primary issues to solve, and they can be solved in a solid state design just as they are in a tube design. 



When the QEX article came out, I contacted JA1DJW about reproducing his article.  He was very kind and sent me many emails with details, pictures  and some of the critical parts for the amp.    I think there are two fundamental reasons the 2.5k isn't rated for full power output in continuous mode.  



The first reason is the power supply isn't rated for continuous duty and is maybe a bit under sized for the application.   A secondary reason would be the heat issue.  Nobuik sent me a heat spreader but I opted not to use it since the heat spreader is about 3.5" x 3.5" x 3/8" copper.   I opted to use a 12 " x 8" x 1/2"   heat spreader with "copper fins"  attached and replicated his machine work layout  onto it.   Efficiency is more along the order of 60% at the worst, usually better though.  





Paul, kg7hf 









From: Dan Levin <dan at andlev.com> 
Subject: Re: [Amps] New 2 PA design 

The big issue with parts like the ARF-1500 is managing the heat.  For 
high duty cycle use, like contesting or RTTY (or worse yet, contest 
RTTY :-) ), you are dealing with dissipating something like 1500 watts 
of heat (assuming 50% efficiency running class AB) being generated in 
an area about one inch by three inches. 


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