[AMRadio] Viking II Power Mod

Thu Oct 20 21:04:12 EDT 2011

If you plan to use it on CW by all means go forward. But if you plan to 
use it on AM, you need to listen to these guys (unless you like to 
splatter). They are dead on correct. You can't defy physics.

73,
Darrell, WA5VGO

On 10/20/2011 7:26 PM, Bernie Doran wrote:
> Ron you just killed the 813s!!  unless you are using them on CW.  if you are
> talking about an AM linear you must load them heavily so that your output is
> no more than 1/3 of the plate dissipation.  They have to be able to produce
> the peak power under modulation. That level is about four times carrier
> power.   with no modulation the carrier efficiency is low, about 33 percent.
> That applies to all of the low level modulation schemes.  It is a complete
> waste of time as you will not notice any difference from what you have.   If
> you have the 813 data in front of you, I hope so. look at the class B
> ratings  and the grid mod ratings( I have it in front of me) you will see
> that the output is about 70 watts per tube.  That is what you will get
> before losses as an AM linear.     Of course you appear to have your mind
> made up, so go ahead and destroy them!!!
>
>    ----- Original Message -----
> From: "W6OM"<w6om at cox.net>
> To: "Discussion of AM Radio in the Amateur Service"
> <amradio at mailman.qth.net>
> Sent: Thursday, October 20, 2011 2:28 PM
> Subject: Re: [AMRadio] Viking II Power Mod
>
>
>> Thanks Eddy
>>
>> Interesting point. 3 X 813's at 2800V and 500 ma delivers a lot more than
>> 180 watts if the 813 spec sheet is accurate.
>>
>> It's just a hunch but I think I'll give it a try anyway, if not workable I
>> will just build a big 8 -10 db attenuator.
>>
>> Thanks again for your thoughts, that is what I was looking for.
>>
>> Ron W6OM
>>
>> Phone:  949-533-7958
>>
>> Fax:       949-559-6209
>>
>> Skype:  Ron.Weaver3
>>
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>> ----- Original Message -----
>> From: "Eddy Swynar"<deswynar at xplornet.ca>
>> To: "Mel Farrer"<farrerfolks at yahoo.com>; "Discussion of AM Radio in the
>> Amateur Service"<amradio at mailman.qth.net>
>> Sent: Thursday, October 20, 2011 10:30 AM
>> Subject: Re: [AMRadio] Viking II Power Mod
>>
>>
>>> Hi Ron,
>>>
>>>> Greetings everyone.  I have a simple question concerning my old Viking
>>>> II.   I am just finishing up a 3 X 813 linear and need to consider how
>>>> to
>>>> drive it with the Viking II.
>>>>
>>> I don't think it'd be worth your while to even bother...
>>>
>>> Consider the math: three 813s would give you, what, some 180-watts of
>>> carrier output as an AM linear, right? Well, you're probably already
>>> getting 100-watts of carrier output from that V2 as it stands now. The
>>> difference would be a mere 80-watts with the 813s, not even twice what
>>> the
>>> V2 is already giving you...
>>>
>>> And keep in mind, that for a 3 db. increase in signal strength, you'd
>>> need
>>> to DOUBLE the power...and for a just perceptible increase in power, you'd
>>> need at least a 6 db. increase.
>>>
>>> It just ain't worth the effort, IMHO...
>>>
>>> ~73~ de Eddy VE3CUI - VE3XZ
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