[ARC5] ARC-5 on 20 meters

[Fuqua, Bill L]

  Also, if you tune the output to the fundamental frequency and add screen modulation via a center tapped
secondary of the modulation transformer,i.e. audio to screens 180 degrees out of phase, you have a double sideband
reduced carrier transmitter.
73
Bill 
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From: ARC5 [arc5-bounces at mailman.qth.net] on behalf of Fuqua, Bill L [wlfuqu00 at uky.edu]
Sent: Friday, December 30, 2016 4:19 PM
To: Dennis Monticelli; Jim Wiley
Cc: ARC-5; Dave Merrill
Subject: Re: [ARC5] ARC-5 on 20 meters

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  If you look at the push push doubler, the internal capacitance of one tube cancels out that of the other.
Secondly, frequency multipliers are often used for load isolation to prevent oscillator pulling. Much better than buffers.
73
Bill wa4lav
_________
________________________________________
From: Dennis Monticelli [dennis.monticelli at gmail.com]
Sent: Friday, December 30, 2016 10:39 AM
To: Jim Wiley
Cc: Brian; Fuqua, Bill L; Dave Merrill; ARC-5
Subject: Re: [ARC5] ARC-5 on 20 meters

You should not need PA neutralization in doubling service.

However, one still has to pay attention to stray 14 Mc energy getting into the 7Mc osc circuitry because interactions could still occur.  Given the layout of the ARC-5 I would not expect that to be a problem unless it sneaks in via some other "unauthorized" mods.

Dennis AE6C

On Fri, Dec 30, 2016 at 2:02 AM, Jim Wiley <jwiley at gci.net<mailto:jwiley at gci.net>> wrote:
Well, it's been the better part of 60 years since I fooled with an ARC-5 rig, but I think if you are running it as a doubler, neutralization is not needed.   Could be wrong here, and if so I am confident someone will step in to correct me.

- Jim, KL7CC



On 12/30/2016 12:37 AM, Brian wrote:
Any suggestion for neutralisation of the finals?
73 de Brian, VK2GCE.

On Friday, December 30, 2016 12:56 PM , Bill said:

 A better way to make the output a doubler is to loose the neutralization capacitor and operate the grids of the 1625's in push pull but retain
the parallel plates. You then have a class-c push-push doubler. The fundamental and third harmonic will cancel out and you will also have
better efficiency.
 73 Bill wa4lav
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