[Amps] 2 kW amp project

Tue Nov 22 01:13:56 EST 2005

That's right Pat, but in the same time I can match most antennas with the 
tank coil of the Emtron DX4 as well, though no automatic.
However, on the band one can notice the difference between the PW1 and the 
DX4, but not because the first one has the auto tuner ;-)

Cheers, Dick

----- Original Message ----- 
From: "Pat Poirier" <hkman at comcast.net>
To: "PA3DUV" <pa3duv at planet.nl>
Sent: Tuesday, November 22, 2005 1:31 AM
Subject: Re: [Amps] 2 kW amp project

> Dick,
>
> You forgot to give the PW1 credit for the weight of the 1000 ++ watt 
> automatic antenna tuner that is built into the amplifier. I think people 
> buy the PW1 for the hands free operation and the ability to remote the 
> amplifier, not the pounds per watt ratio.
>
> 73,
> Pat W1KA
>
> ----- Original Message ----- 
> From: "PA3DUV" <pa3duv at planet.nl>
> To: <g3rzp at g3rzp.wanadoo.co.uk>; <amps at contesting.com>
> Sent: Monday, November 21, 2005 4:24 AM
> Subject: Re: [Amps] 2 kW amp project
>
>
>> 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
>>>
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>>
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