[Boatanchors] Using a SG-230 tuner on AM

[D C *Mac* Macdonald]

The doubled current IS supplied by the power supply,
but NOT just the transformer but the filter capacitors
on a VERY short term basis AND the "spikes" supplied
by the modulator and ITS power supply.
 
73 - Mac, K2GKK/5
(Since 30 Nov 53)
OKlahoma City, OK
 

p.s.  Spectrum analyzers with which I'm familiar
shows ONLY voltage level.  I believe that an
average-reading Wattmeter would show 1.5 times
the carrier reading with 100% modulation by a
single tone.  It HAS been a while since I have
made that test on a spectrum analyzer, but I
service FAA's VHF and UHF transmitters which
are set for 10W carrier power.  Set up for 90%
modulation with 1 kHz tone, the Marconi (and other)
service monitors show approximately 14W.  They
will show 15W at 100% modulation.

p.p.s.  I am not familiar with using a peak-reading
wattmeter, depending on the decay time-delay of the
particular wattmeter, I can see where you would never
see the actual peak ENVELOPE power.
 
 

----------------------------------------
> From: km1h at jeremy.mv.com
> To: k2gkk at hotmail.com; rbethman at comcast.net; boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Using a SG-230 tuner on AM
> Date: Sun, 9 Aug 2009 19:36:30 -0400
>
> Where is this doubled current coming from? There is only one voltage source
> feeding the final and that certainly isnt pulling 2X key down.
>
> I dont see 4X power on a peak reading wattmeter or spectrum analyzer.
>
> Carl
> KM1H
>
> ----- Original Message -----
> From: "D C *Mac* Macdonald" 
> To: ; 
> Sent: Sunday, August 09, 2009 4:15 PM
> Subject: Re: [Boatanchors] Using a SG-230 tuner on AM
>
>
>>
>> I'm certainly not looking to start a "firefight."
>>
>> HOWEVER, if you will display an unmodulated "carrier" on an
>> o'scope, then modulate it 100%, the VOLTAGE when amplified
>> will double. Since ohms law states that if you double the
>> voltage you will also double the current.
>>
>> Since P = I x E, 2I x 2E will give you 4P.
>>
>> It's basic Electronics 101.
>>
>>
>> 73 - Mac, K2GKK/5
>> Oklahoma City, OK
>>
>>
>>
>> ----------------------------------------
>>> Date: Sun, 9 Aug 2009 16:11:02 -0400
>>> From: rbethman at comcast.net
>>> To: boatanchors at mailman.qth.net
>>> Subject: Re: [Boatanchors] Using a SG-230 tuner on AM
>>>
>>> This always starts "some" sort of a firefight.
>>>
>>> I can argue either side. The basic reasoning gets down to WHAT
>>> measurement INSTRUMENTS are being used.
>>>
>>> The current 1500W limit is to be measured in PEP. Darn few folks do
>>> so. They are still using equipment that doesn't get the job done
>>> correctly.
>>>
>>> The only thing I could remotely suggest is to TRY the tuner on a single
>>> antenna with a radio of the desired output. Brief duration as I know
>>> Carl WOULD do.
>>>
>>> Then go from there.
>>>
>>> I'm going to leave the firefight. Been in to many real ones.
>>>
>>> Bob - N0DGN
>>>
>>> D C *Mac* Macdonald wrote:
>>>> At 100% modulation peak, the instantaneous voltage
>>>> AND current are both double the static values.
>>>>
>>>> V^2 times I^2 gives you four times the static power.
>>>>
>>>> Current FCC rules allow for 1.5 kW output power.
>>>> That is why the old kilowatt rigs such as Collins
>>>> KW-1 and Johnson Desk Kilowatt can now only be run
>>>> at 375 Watts carrier power.
>>>>
>>>> 73 - Mac, K2GKK/5
>>>> Oklahoma City, OK
>>>>
>>>
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