[AMRadio] AM Amps


Gary Schafer garyschafer at comcast.net
Fri Jan 14 11:55:36 EST 2005


No, didn't mean it to be rhetorical. A legitimate question I thought.
With some of the guys on here not quite understanding how to set up an 
amp properly for AM operation it didn't sound like you had yours set up 
properly if you were operating it like that on AM.
Especially when you eluded that you only operated it at 1400 watts 
carrier into a dummy load. That would seem to indicate that you would 
expect peak power to be well over 1400 watts and into the illegal range. 
Which of course it would not be capable of.

For AM operation with your setup the drive needs to be reduced to around 
30 watts carrier after the amp is tuned up at the 1400 watt out level.

Just wondering what method you use to reduce the DX100 output to 30 watts?

73
Gary  K4FMX




James M. Walker wrote:
> That's a rhetorical question right?
> Jim
> WB2FCN
> 
> 
> Gary Schafer wrote:
> 
>>How do you reduce the drive for AM? I take it that is how you operate CW?
>>
>>73
>>Gary  K4FMX
>>
>>James M. Walker wrote:
>>
>>>Hum,
>>>4-1000A G.G. amplifier, 3000 VDC plate, 700 MA Plate I, 500 MA
>>>Grid I, with 125 Watts out of DX-100 running apprx 2100 W input and
>>>dissipating 670 watts plate = approximately 1430 watts output!
>>>
>>>While the carrier level into 50 ohm dummy load is 1400 watts measured
>>>and a really NICE orange glow! This is with a 200 cfm blower, air system
>>>socket and chimney.
>>>
>>>Jim
>>>WB2FCN
>>>
>>>----- Original Message -----
>>>From: "Jim candela" <jcandela at prodigy.net>
>>>To: "Discussion of AM Radio" <amradio at mailman.qth.net>
>>>Sent: Wednesday, January 12, 2005 7:07 PM
>>>Subject: RE: [AMRadio] AM Amps
>>>
>>>
>>>
>>>
>>>>Darrell,
>>>>
>>>>That amp you built with the 4-1000 was a "killer" in more ways than one!
>>>>Time for a confession..
>>>>
>>>>Regards,
>>>>Jim
>>>>WD5JKO
>>>>
>>>>-----Original Message-----
>>>>From: amradio-bounces at mailman.qth.net
>>>>[mailto:amradio-bounces at mailman.qth.net]On Behalf Of Darrell, WA5VGO
>>>>Sent: Tuesday, January 11, 2005 6:04 PM
>>>>To: Discussion of AM Radio
>>>>Subject: Re: [AMRadio] AM Amps
>>>>
>>>>
>>>>At 04:21 PM 1/11/2005 -0500, you wrote:
>>>>
>>>>
>>>>
>>>>>In a message dated 1/11/05 12:14:43 PM, ronnie.hull at glowbugs.com writes:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>well all I can say is it works.. works well as a matter of fact, and
>>>>>
>>>has
>>>
>>>
>>>>>>been for 6 years :)
>>>>>>I typically run between 350 and 400 watts of carrier every day. It
>>>>>
>>>looks
>>>
>>>
>>>>>>great on the scope. Modulation envelope is perfect. 100% modulation.
>>>>>
>>>In
>>>
>>>
>>>>6
>>>>
>>>>
>>>>>>years Ive only lost one tube, and I accidently broke that one.
>>>>>>
>>>>>>
>>>>>
>>>>>I have to agree with Gary.   You're seeing 1600 watts PEP and 400W of
>>>>
>>>>carrier
>>>>
>>>>
>>>>>OUT with a pair of GG 813s???   Does not compute!   Just curious, are you
>>>>>talking about 400W INPUT power to the linear under carrier only condx
>>>>>maybe?   If
>>>>>so, this would work out to about 133W carrier OUT and each 813
>>>>
>>>dissipating
>>>
>>>
>>>>>about 133W which would make more sense.
>>>>>
>>>>>Dennis D. W7QHO
>>>>>Glendale, CA
>>>>
>>>>
>>>>I'm with Dennis and Gary. To run a linear amplifier at 375 watts of
>>>
>>>carrier
>>>
>>>
>>>>and 100% modulation, you will need around 800 watts of plate dissipation.
>>>>For a short time a number of years ago, I tried running an AF-68 and a
>>>>4-1000A linear amplifier. I could never get more than around 450 watts of
>>>>carrier and stay linear............I didn't need a heater in the shack
>>>>either.
>>>>
>>>>73,
>>>>Darrell, WA5VGO
>>>>
>>>>
>>>>
>>>>73,
>>>>Darrell, WA5VGO
>>>>
>>>>
>>>>
>>>>
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>>>>
>>>
>>>
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>>
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