[Amps] 2 kW amp project

[PA3DUV]

Peter,

The weight of an Icom PW1 solid state power amplifier (1 kW out) is 25 kg@ 
1000 watt output (40 watt/kg)
The weight of an Emtron DX2 twin GU74B tube amp is 27 kG @ 1500 watt output. 
(56 watt/kg)
The weight of an Emtron DX4 twin GU84B tube amp with 3 phase PSU is 76 kg @ 
6000 watt output. (79 watt/kg)

The PW1 is equipped with a SMPS, the tube amps with tape wound transformers 
with a FWD

The tube amp wins hands down when it comes to power/weight ratio.

Cheers, Dick Knol
PA3DUV





----- Original Message ----- 
From: "Peter Chadwick" <g3rzp at g3rzp.wanadoo.co.uk>
To: <amps at contesting.com>
Sent: Monday, November 21, 2005 9:36 AM
Subject: Re: [Amps] 2 kW amp project


> The article in QEX was not a simple multi band device, although I suppose 
> it could eventually get to that. It uses a lot of cheap FETs, and goes up 
> to 7 MHz. Going up to 28MHz with cheap FETs may not be on. The output 
> transformer is fearsome, with 1/2 inch copper tubes silver soldered to 1/8 
> inch thick copper heatspreaders. Copper is vile stuff to work, too, when 
> it comes to drilling and tapping. Incidentally, it behoves one to be 
> careful when working with sheet copper, since any small cuts that you get 
> from it frequently tend to get infected and take a long time to heal - 
> although not as long as RF burns!
> The problem with Class E is that it isn't linear, although it modulates 
> well for AM. This suggests that for SSB, either a Cartesian or Polar loop 
> approach is required, which adds considerably to the complexity - possibly 
> a Callum modulator could be used, but that's fairly critical on set up, 
> too. Personally, I need some convincing that at the end of the day, for 
> homebrew ham use, the big SS amp really wins out. From the viewpoint of 
> interesting technical experimentation, there is a lot of fun to had from 
> it, though. One major factor for a linear amplifier is still the 
> heatsinking. Teaching grandmama to suck eggs here, but a larger allowable 
> temperature rise means that the cooling is less critical.
> Accepting the switching regulator (and high voltage SMPS are available), I 
> doubt the tube amp ends up much different in size and weight. There is the 
> minor problem of making sure the SMPS is electrically quiet enough, of 
> course. OK, you can switch it off on receive, but if it requires a surge 
> limitation on input current, QSK would be a problem.
> The tube amp with the 75lb HV transformer isn't likely to get easily 
> knocked off the table, though!
>
> 73
>
> Peter G3RZP
>
>
>
>
>
>
>
> ========================================
> Message Received: Nov 21 2005, 12:48 AM
> From: "Bill Turner"
> To: "wc6w at juno.com" , Amps at contesting.com
> Cc:
> Subject: Re: [Amps] 2 kW amp project
>
> At 09:54 AM 11/20/2005, wc6w at juno.com wrote:
>
>>Hi Bill,
>> Item #1 is easy. Get a surplus 48V switching power supply from
>> the telecom world.
>>
>> My best suggestion for #2 is a dual pi-net. 50 ohms to 500-1000
>> ohms back to 25-100 ohms. This provides both matching & harmonic
>> suppression. Two switched coils, 3 (small) vac. variables, plus
>> some ceramic padders for 80 & 160. Physically about 6" x 7" x 12"
>> including motor drives for the caps & 10 position bandswitch.
>>
>>73 & Good morning,
>> Marv WC6W
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Sounds good. I almost wish I hadn't started the 8877 project but it's
> too far along to stop now. :-)
>
> Where does one find the surplus telecom supplies? Can you suggest a
> manufacturer of new ones?
>
> 73, Bill W6WRT
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps