[ARC5] My ARC-5 40 meter station

[Mike Morrow]

>An important reason to run less carrier power is, as I have discovered by experiment (and confirmed by others at AMfone.net) that to get clean output when using screen modulation, it is necessary to load the finals well beyond the point of maximum carrier output.
>
>The original transmitter used plate modulation (and a tertiary winding on the modulation transformer for additional screen modulation). Sure,  I could get a lot more than 8 watts carrier (originally I did set it to around 15 watts but then the upward modulation starts to flatten and disappear. Even at 15-20 watts carrier, although the transmitter is currently capable of 64 watts PEP by direct measurement, the scope waveform does not look good at all, and I would not put such a transmitter on the air!
>The cleanest signal from a screen modulated ARC-5 (and probably any other grid-modulated transmitter) is not the one that gives maximum carrier output.
>
>-Charles
>WB3JOK/0
>
>From: J Mcvey 
>Sent: Saturday, February 21, 2015 7:27 PM
>To: Charles ; ARC-5 
>Subject: Re: [ARC5] My ARC-5 40 meter station
>
>When I get mine going, I will let you know what output I measure. I expect less than the specified power from mine because I am using only 440V on the plate. That 40 volt difference on yours shouldn't be all that noticeable at the antenna. Maybe its off resonance?
>
>However I am going to play with the screen voltage (I used an adjustable ceramic wire wound resistor for this purpose) a bit to try to optimize the circuit.
>I bet I still get more than 8 watts though...
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>On Saturday, February 21, 2015 7:17 PM, Charles <charlesmorris800 at centurytel.net> wrote:
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>I am acquainted with the design specs. 15 watts is with new 1625’s and with the 600 volt B+, and I only had 560V and a pair of well used tubes...
>I also don’t believe that 15 watts of carrier is at 100% modulation.
>
>Remember also that I added the series matching cap so the transmitter loads properly into 50 ohms, which is easier and results in the same output as a unun...
>http://www.w7ekb.com/glowbugs/Military/DaveStinsonARC-5Article.pdf
>http://www.w7ekb.com/glowbugs/Military/DaveStinsonARC5Info.pdf
>
>The prevailing (but not unanimous) opinion seems to be that building a unun is not worth the extra effors.
>
>
>From: J Mcvey 
>Sent: Saturday, February 21, 2015 5:19 PM
>To: Charles ; ARC-5 
>Subject: Re: [ARC5] My ARC-5 40 meter station
>
>You get alot more than 8 watts out. The output was designed for low impedance (5-12 ohms ) a few hundred ohm capacitive 5-J200 antenna.
>Specs say you should exceed! 40 watts in CW  and have a 15 watt voice carri
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