----- Original Message -----
From: "Roger" <sub1@rogerhalstead.com>
To: "Carl" <km1h@jeremy.mv.com>
Cc: <dezrat1242@yahoo.com>; <amps@contesting.com>
Sent: Friday, December 04, 2009 4:42 AM
Subject: Re: [Amps] Advice
>
>
> Carl wrote:
>> I believe that goes way back to the "if one is good then 2 must be better
>> phrase"
>>
>> Since a single ended 100TH, for example, couldnt make a KW on CW then
>> using a pair solved the problem. It actually goes mack to the original
>> discovery of PP or parallel tubes sometime in the 20's or earlier.
>>
>> Its also a lot easier to run a pair of 8877's then stepping up to 3 kW +
>> Pd tube such as the 3CX3000A7 which is a drive and filament power hog.
>> The tube of choice then is the YC-156 which has its own issues.
>>
>> And for the cost involved 3 or 4 813's can make some serious RF. I use 4
>> in one of my AM amps.
> And they are relatively cheap and available. I saw a bunch of them for
> $25 each last week.
> Remember the "sweep tube" amps of the 70's? AKA the GLA1000 and a bunch of
> others.
> Thats when tubes were really cheap and plentiful.
>
> 73
>
> Roger (K8RI)
The 813 remains as the best bargain on the market with maybe the 803 or
814/VT-154 in 2nd place. Powers range from modest to legal limit when run in
4 paks..
The 813 (as well as the others) is seriously underated by todays standards.
I estimate a realistic Pd of around 225-250W in CW/SSB. It shows
substantially less color than a 572B.
Carl
KM1H
>>
>> ----- Original Message ----- From: "Bill, W6WRT" <dezrat1242@yahoo.com>
>> To: "Roger" <sub1@rogerhalstead.com>
>> Cc: "Carl" <km1h@jeremy.mv.com>; <amps@contesting.com>
>> Sent: Thursday, December 03, 2009 4:21 PM
>> Subject: Re: [Amps] Advice
>>
>>
>> ORIGINAL MESSAGE:
>>
>> On Wed, 02 Dec 2009 22:13:02 -0500, Roger <sub1@rogerhalstead.com> wrote:
>>
>>> Tubes should always be used as a pair,
>>> except for 813's and 572's and then you use 4 of them.
>>
>> REPLY:
>>
>> First time I've ever heard "tubes should be used as a pair". I have heard
>> the
>> opposite: "If you need more power, don't use two tubes, get a bigger
>> tube".
>>
>> Care to elaborate?
>>
>> 73, Bill W6WRT
>>
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