[TowerTalk] What am I missing....balun

[Roger (K8RI) on TT]

Not long ago, it was easy to import some serious amps as long as that 
manufacturer didn't have a US outlet. The Emtron DX-2sp loafs along at 
the legal limit.  It is quite capable of putting out 2500 PEP, but it 
takes that kind of overhead to run 1500 out on digital. Tuned properly, 
it puts out a very clean, legal limit signal. There were amps with a 
pair of the same tubes, and another with a 4CX5000 (3 phase PS). Run at 
1500 out at 100% duty cycle and the push pull cooling goes into high 
gear and it is loud in a small room, neglecting the heat it puts out.  
Add some compression while running 1500 PEP out and that amp goes into, 
high blower.

Two large computers, plus my old 76A would drive me out of this room in 
the summer. The CPUs use 200 watts, give or take with one at 220W under 
full load. The video cards take 300W, so I'm looking at roughly 600W  ea 
for 2 computers plus the heat from the FT5000MP and the amp.

That's 2500 At a 20% duty cycle, or only 625 W average with the DX-2sp.
Many home brew amps use tubes with handles.  Manual tune and relatively 
inexpensive compared to Eimac 8877s.  I have a 4CX3000 and a couple of 
sockets that I'll probably never finish..  New and complete sockets for 
that tube are definitely not cheap at $1600! Running the legal limit, 
that tube could probably be cooled with a muffin fan.

The drawback?  Many of these tubes take more power to light the fire, 
than the average station runs. Add to that, the connectors, coax, and 
antennas we use are not rated for a lot more than the legal limit. Oh! 
Those amps are not only loud on-the-air, they are loud in the shack, 
often necessitating a remote location for the amp
You can modify amps, and RF generators that weren't designed 
specifically for ham radio, regardless of their designed power, or gain 
as well  We are well past needing the gain limitations that were 
designed to keep ham amps out of CB hands.

The 3CX3000A7 can put out a very clean signal. Cleaner than most SS 
rigs, but if memory serves as in IIRC, that tube is 10" tall and weighs 
close to 9#? Not exactly the basis for a compact amp.

With the new transistors, pre distortion, and cleaner rigs SS legal 
limit plus amps will soon be common place...for those who can afford 
them. For now, they exist, but in the experimenter/home brew crowd.

73, Roger (K8RI)

On 2/17/2017 1:37 PM, StellarCAT wrote:
> seriously? There are amps that are sold all-day-long that will easily 
> do 3 even 4 or more thousand watts! The statement when advertised for 
> sale as "used" that says "to a dummy load" as if they think the 
> reviewing audience is dumb enough to think that is how it was tested 
> or worse used!
>
> Antennas that come with baluns and hardware designed for 5KW .... this 
> happens all the time.
>
> 200W on 30 meters?
>
> there's nothing illegal about overbuilding something and selling it as 
> such as long as it doesn't require FCC cert ...
>
> Gary
>
>
> -----Original Message----- From: Richard Solomon
> Sent: Friday, February 17, 2017 1:17 PM
> To: towertalk
> Subject: Re: [TowerTalk] What am I missing....balun
>
> Just a side note, but I wouldn't
> be so quick to advertise that I sell
> components to those who violate
> Federal Law.
>
> 73, Dick, W1KSZ
>
> On Fri, Feb 17, 2017 at 11:12 AM, Jim Thomson <jim.thom at telus.net> wrote:
>
>> Date: Fri, 17 Feb 2017 07:41:09 -0700
>> From: Chris <EZRhino at fastmovers.biz>
>> To: "towertalk at contesting.com reflector" <TOWERTALK at contesting.com>
>> Subject: Re: [TowerTalk] What am I missing....balun
>>
>> Is there any chance this is an April Fool's joke?
>>
>> Chris
>>
>
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>
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-- 

73

Roger (K8RI)


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