[Amps] QEX Innovative Tube Linear?

[R L Measures]

On Jul 7, 2006, at 9:06 AM, Will Matney wrote:

> Craig,
>
> My guess is they lowered the anode voltage and current on each tube  
> to help with the IMD problems.

Lower anode potential typically increases IMD because the  
characteristic curves tend to bend at lower voltages while they are  
flat at higher ones. .

> Running sweep tubes at 1100 to 1200 Vdc sure isn't a good idea as  
> that's over their maximum rating. Around 900 Vdc at the most for  
> tubes like a 6LF6, etc. Smaller sweep tubes (6LQ6, 6JE6, ect) ought  
> to be ran a little less. I ran a quantity of eight 8908's or  
> M-2057's G-G to get 1500+ kW PEP out of a sweep tube amp using 900  
> Vdc on the anodes. They were capable of 300 watts PEP each being  
> grid driven. The 8950 or 6LF6 was some amount less, around 175 to  
> 200 watts each grid driven. I built one using two of the EL519's  
> (6KG6A), and the most I could squeeze out of that little grid  
> driven amp was about 300 watts PEP, so figure them at 150 watts PEP  
> out each maximum. Running them G-G would probably yield a less on  
> AM, but about the same with SSB. That's just from my expeirence  
> with them. I'd like to see the article my self and see what tubes  
> and voltages they used.
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR  ***********
>
> On 7/7/06 at 11:50 PM zdtech wrote:
>
>> Hi Dick
>>
>> Most interesting, i just wonder how they went about improving the
>> terrible IMD from Sweep tubes? It would  be great if the same  
>> technique
>> could be used with some better quality transmitting tubes.  What
>> magnitude of improvement in 3rd order IMD could the author of the
>> article achieve? I look forward to reading about it.
>>
>> Craig
>> VK3HE
>>
>>
>> Dick Hanson wrote:
>>> It is a combination of TV sweep tubes with a HV switching supply.
>>> Pretty decent 3rd and 5th order distortion products.
>>> It only works on frequencies below 20 meters. It is quite small.
>>> That's about it.
>>> 73
>>> Dick, K5AND
>>>
>>> -----Original Message-----
>>> From: amps-bounces at contesting.com [mailto:amps- 
>>> bounces at contesting.com] On
>>> Behalf Of zdtech
>>> Sent: Friday, July 07, 2006 8:22 AM
>>> To: amps at contesting.com
>>> Subject: [Amps] QEX Innovative Tube Linear?
>>>
>>> Anyone receive their July/August copy QEX? There is an article in  
>>> there
>>> called  "A Innovative Tube Linear" I am just wondering what is so
>>> innovative about the linear? My issue  of QEX arrives quite late  
>>> after
>>> the US publication date, so i was wondering if its something to look
>>> forward too.
>>>
>>> Craig
>>> VK3HE
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>>>
>>
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R L MEASURES, AG6K. 805-386-3734
r at somis.org