Carl,
I need to get a well drilled then. Had one as a kid and that brings
back memories.
And congratulations on getting the 572b's to sing. On the ones I've
seen (stock units), the roll-off in po as a result of drops in
efficiency at 15m and above is huge.
What is your secret for getting good efficiency out of these tubes at
that high frequency>
73/jeff/ac0c
Carl wrote:
> Well, the water here comes out of a 660' deep well and has a bit of
> iron in it but none of that funny stuff you get from town water.
>
> Its very easy to get power from 572B's on 6M since they are full power
> rated to 54 mHz. I certainly wouldnt run RTTY or digital that way but
> CW/SSB doesnt bother them a bit. I test every conversion at 1 minute
> full bore key down; the plates get a bit of dark red near the end.
>
> Im not the only one who converts these either.
>
> Carl
> KM1H
>
>
>
>
>
> ----- Original Message ----- From: "Jeff Blaine"
> <keepwalking188@yahoo.com>
> To: "Carl" <km1h@jeremy.mv.com>
> Cc: "George Knight" <gkve3ltu@sympatico.ca>; <amps@contesting.com>
> Sent: Thursday, March 12, 2009 6:20 PM
> Subject: Re: [Amps] 810 Amplifier
>
>
>> Carl,
>>
>> Can you send us some of whatever is in the water up there? Because
>> the SB200's in this part of the world are sure in need of that magic
>> elixor.
>> What's the plate dis of a pair of 572b? Something like 360w? Maybe
>> that is the answer to my question on the other subject of anode dis
>> limits...
>>
>> Clearly a sample size of 250 sb200 converted to 6m service is an
>> extreeme case (given the tubes start running out of gas at 30mhz more
>> or less) - and a large sample set of 200 statistically is very
>> significant.
>> If that tube will work at 2x the plate dis in the north east, then I
>> surely should be able to get the similar multiplier from my
>> conversion project here in the fly-over country.
>>
>> 73/jeff/ac0c
>>
>> Carl wrote:
>>> My 2 cents anyway. :)
>>>
>>> Yep, I agree with the above<G>
>>>
>>> In my experience with converting around 250 SB-200's to 6M I can
>>> unequivocally say that a majority still have the original Cetrons
>>> installed and will run 700W + key down on 6M on a 240V AC line. A
>>> bit less on 120V.
>>>
>>> Your milage may vary.
>>>
>>> Altho I feel the 4 x 810 project is a wasted effort it is possible
>>> to do it with 4 x 813's and cover 160-10M.
>>>
>>> Carl
>>> KM1H
>>>
>>>
>>> ----- Original Message ----- From: "Jeff Blaine"
>>> <keepwalking188@yahoo.com>
>>> To: "George Knight" <gkve3ltu@sympatico.ca>
>>> Cc: <amps@contesting.com>
>>> Sent: Thursday, March 12, 2009 3:21 PM
>>> Subject: Re: [Amps] 810 Amplifier
>>>
>>>
>>>> George,
>>>>
>>>> You may want to consider a trio of GI7B (less complicated) or
>>>> perhaps a
>>>> 4cx800 (more complicated) if you run something other than SSB. These
>>>> ceramic tubes are far more durable than the glass counterparts in my
>>>> experience.
>>>>
>>>> I bought 3 sets of 572b last year in a test to determine the actual
>>>> life
>>>> of the 572b vs. duty cycle because the data for contempary versions of
>>>> the 572b are hard to come by. None of the tubes could reach the 25
>>>> hour
>>>> key-down accumulated time before reaching 500w output for the set. I
>>>> have seen the stories of guys with 500w out on a 25 year old set of
>>>> tubes in a SB200, but that is clearly the excepiton and not the rule.
>>>> The 572b at 1200w out of a set of 4 is really something that can
>>>> only be
>>>> sustaned in the long term if conditions are perfect and the winds
>>>> are at
>>>> your back.
>>>>
>>>> So while your mileage may vary, I can say categorically that at 1200w
>>>> out as the goal (meaning net average power, not PEP or peak or
>>>> whatever), the 572b set of 4 will do it. But just not for very long.
>>>>
>>>> My 2 cents anyway. :)
>>>>
>>>> 73/jeff/ac0c
>>>>
>>>>
>>>> George Knight wrote:
>>>>> Thanks to all who contributed. Although there is a lack of
>>>>> unanimity in the responses, I think I will go ahead with the
>>>>> project. In the event that it turns out to be a total failure, it
>>>>> will be quite easy to change the sockets to accept 572B tubes and
>>>>> get into the 1200 watt output class.
>>>>> '73, George, VE3LTU.
>>>>> _______________________________________________
>>>>> Amps mailing list
>>>>> Amps@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> Amps mailing list
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>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>
>
>
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