[Amps] What tube?

[Carl]

The 4-400 in GG have less gain than a 3-500 and a pair is usually good for 
1000W in a full GG SB-220 thru 10M at 100W drive unless they are tired 
pulls. I converted an ISM amp with a pair of them to 6M many years ago and 
after converting the PS to a big cap and tossing the choke they easily ran 
1500W at 3400V and 120W drive from my amp bench transverter.

Carl
KM1H



--------------------------------------------------
From: "Larry" <larry at w7iuv.com>
Sent: Wednesday, January 28, 2015 11:12 AM
To: "Manfred Mornhinweg" <manfred at ludens.cl>; <amps at contesting.com>
Subject: Re: [Amps] What tube?

> AS far as I know, there is only one tube(s) that meet your requirements; a 
> pair of 3-500Zs.
>
> If you drop the "instant-on" requirement, there are quite a few other 
> possibilities.
>
> One other possibility if you can handle it might be 2X or 3X triode 
> connected 4-400As. I've not been able to reliably get 1500 out on all the 
> HF bands with a pair, but three in parallel makes it easy. See my web page 
> for a 3 x 4-400A 40 meter monobander.
>
> 73,
>
> Larry - W7IUV / WH2XGP
>
>
> On 28-Jan-15 6:00 AM, Manfred Mornhinweg wrote:
>> A question to all those of you who have used many different tubes:
>>
>> What tube(s) would you recommend for a legal limit HF amplifier, to get
>> as close as possible to the following goals:
>>
>> - Class AB2 operation at high efficiency, low idling power, at
>> acceptable IMD (doesn't need to be brilliant).
>>
>> - Ideally grounded grid triode, but a tetrode with screen supply is
>> acceptable if a GG triode won't do it.
>>
>> - Instant-on filament, or at least quick heating (no more than 10 
>> seconds).
>>
>> - Easy cooling requirements, so that a low noise fan or blower can be
>> used. Maybe conduction cooled or water cooled.
>>
>> - Available and reasonably priced.
>>
>> I know I'm asking to much, but I would like to analize the best options
>> out there!
>>
>> Manfred
>>
>> ========================
>> Visit my hobby homepage!
>> http://ludens.cl
>> ========================
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