I just looked at the curves for several sweep tubes including the ones I
mentioned, and they didn't start to bend until around 250 Vdc and below. They
were flat from there on up in voltage until the maximum permissable anode
voltage rating. Running them just at or below the maximum permissable anode
voltage would be recommended. Some designers of the past tried to run them at a
much greater anode voltage than what the spec sheets say is permissable. I'll
try to post the different maximum anode voltages later this evening.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/7/06 at 9:15 AM R L Measures wrote:
>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@contesting.com [mailto:amps-
>>>> bounces@contesting.com] On
>>>> Behalf Of zdtech
>>>> Sent: Friday, July 07, 2006 8:22 AM
>>>> To: amps@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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>>>> Amps@contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
>>>
>>> _______________________________________________
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>>
>>
>>
>> _______________________________________________
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>
>R L MEASURES, AG6K. 805-386-3734
>r@somis.org
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