Comments on Central Electronics 20A

Scott Johnson scottjohnson1 at HOME.COM
Sat Jun 23 10:58:56 EDT 2001

I can't take it anymore. If you people feel you must belittle one
another, please do it without roping in the whole group.  If someone
makes a mistake, reply to them, not the whole list.  I do not feel any
smarter after reading all these rants, and I would rather not have to
sift through all of this.  PLEASE try to be more civiol, and more
private in your derision.

Bob Maser wrote:
> Welcome "no code".
> -----Original Message-----
> From: Glen E. Zook <gzook at HOME.COM>
> Date: Friday, June 22, 2001 9:01 PM
> Subject: Comments on Central Electronics 20A
> >I am new to this particular reflector but feel I must reply to one of
> >today's messages.I do not like the practice of "putting down" other
> >amateurs.  I have always believed that amateurs, in general, are a
> >trusting, helpful bunch of guys and gals (men and women for the
> >politically correct among us). I am against the practice of amateurs
> >"taking advantage" of one another,I am against making "snide" remarks
> >either to someone.  I am definitelyagainst stealing from another amateur
> >(or anyone for that matter!),against running up of fictious repair bills
> >for the purpose of obtaining equipment because the amateur who owns the
> >equipment can't pay the bill, and similar actions.  Frankly, I have seen
> >it all!
> >
> >I am definitely of the "old school" where amateurs help each other. When
> >the following E-Mail was brought to my attention, I was disturbed.
> >
> >Date: Fri, 22 Jun 2001 16:06:35 -0500  From: "k5ceg at"
> >
> >i  see a post a couple of days ago for a modulation transformer for a
> >central electronics 20 a, i am wondering if i missed something.maybe
> >this phasing type exciter had such a thing??? i have 6 of them and cant
> >seem to locate 3 modulations transformers in them.or maybe this was a
> >mistake by someone that held a conditional class license or something.3
> >modulations transformers in a 20a would weigh about 50 lbs or i
> >missed informed or what??? or maybe one needs to go back to
> >school...chuck
> >
> >The Central Electronics Model 20A is one of the first SSB transmitters
> >produced commercially in the United States.  Using a pair of 6AG7 tubes
> >in the final amplifier, it produces a maximum output of 20 watts PEP.
> >This is a complete transmitter, including power supply, utilizing
> >"phase" type generation of the SSB signal instead of the now, more
> >common, "filter" generation.  However, the 20A uses either
> >crystalcontrol, or, a modified ARC-5 command transmitter VFO. The
> >Hallicrafters HT-37 transmitter and the Heath SB-10 SSB adapter are
> >common examples of "phase" generation transmitting equipment
> >
> >The approximate weight of the entire unit is 40 pounds. Since this
> >transmitter does not utilitze the "normal" plate modulation scheme,
> >there is no plate modulation transformer.  However, if there were a
> >plate modulation transformer, the weight of it would be in the
> >neighborhood of a pound, or two, because it would only have to provide a
> >maximum of 10 watts of audio to fully modulate 20 watts This is opposed
> >to the "over 50 pounds" claimed by K5CEG. When used on AM the signal is
> >generated by inserting the carrier (unbalancing the balanced
> >modulator) and was amplified by the pair of 6AG7 tubes which are in a
> >linear amplifier configuration.
> >
> >The schematic refers to the two transformers after the 12AT7 "A F
> >Modulator" tube (their designation) as "Mod Trans" (short for modulation
> >transformers- part number 27A0-79-3).  From the diagrams in the manual,
> >these
> >appear to be cylindrical in nature, probably about 1.5 inches in
> >diameter.  I would doubt that they weigh more than about 0.5 pounds,
> >probably sless.  The SB-10 adapter has two similar transformers in the
> >sideband
> >generation circuitry (also called "modulation transformers" by Heath -
> >p/n 51-38). As in the Central Electronics 20A, those in the Heath SSB
> >adapter are also very small, about 2 inches square by about 2.5 inches
> >high.  These weigh, in my estimation, about 3 or 4 ounces each, not over
> >50 pounds combined weight!
> >
> >The 20A and SB-10 use a 12AT7 as the audio modulator. The 20A manual
> >does not give the impedances of the modulation transformers, the Heath
> >manual does.  The transformers are a 1:1 turns ratio with impedance 20K
> >ohms.  I would think the 20A would be similar.
> >
> >Therefore, calling the transformers labeled as TR-2 and TR-3 "modulation
> >transformers" is completely correct. This is the nomenclature used by
> >Central Electronics and Heath when describing them.
> >
> >As a direct result of this information, I believe that K5CEG owes some
> >heartfelt apologies to those persons he has tried to insult with his
> >comments about needing to go back to school and about their previous
> >class of license.  Unless, of course, he is admitting that he has to go
> >back to school and learn how to read the nomenclature on various
> >manufacturer's schematics, to learn how to properly capitalize his
> >typing (i.e. "I", not "i"), spelling (uses "excellant" on his web site
> >instead of the correct spelling of "excellent" when describing equipment
> >condition on, proper use of the plural noun (used
> >"modulations" instead of "modulation"), improper verbage (used "missed
> >informed" instead of "misinformed"), and so forth .  If that is the
> >case, I am sure that the Paris, Texas, school system has adult education
> >classes that he can attend for the purpose of expanding his knowledge.
> >If he did not mean this action for himself, then I again appeal to him
> >to offer his apologies.
> >
> >Because I am new to the reflector, I was asked by some "older" members
> >to take a look at K5CEG's comments and make my own comments on them.  I
> >have only met K5CEG once, and I am fairly sure that he does not want me
> >to reveal the reason and the results of that particular meeting.
> >
> >Again, I am from the "old school" where amateur radio operators help
> >each other, not try to hurt each other.  So, let's do our best to try
> >and help each other rather than "tearing each other down".  How about
> >it?!!
> >
> >Glen, K9STH

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