<div style="font-family: 'Calibri', 'sans-serif';"><div dir="ltr">
<div dir="ltr">A better way is to leave the supply untouched and use an autotransformer at the input.</div><div dir="ltr">Al </div><div dir="ltr">WB9UVJ</div><div dir="ltr"><br></div><div dir="ltr"><div dir="ltr">Sent from my HTC</div></div>
</div><br><div id="htc_header">----- Reply message -----<br>From: heath-request@puck.nether.net<br>To: <heath@puck.nether.net><br>Subject: Heath Digest, Vol 86, Issue 7<br>Date: Sun, Feb 4, 2018 18:07</div></div><br><div dir="ltr"><pre style="word-wrap: break-word; white-space: pre-wrap;">Send Heath mailing list submissions to
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Today's Topics:
1. HP-23 power supplies - an idea and some questions.
(Kenneth G. Gordon)
2. HP-23 (Mike Fitzgerald)
3. Re: HP-23 power supplies - an idea and some questions.
(Kenneth G. Gordon)
4. Re: HP-23 power supplies - an idea and some questions.
(Kenneth G. Gordon)
5. HP-23 (Mike Fitzgerald)
6. Re: HP-23 power supplies - an idea and some questions. (Glen Zook)
----------------------------------------------------------------------
Message: 1
Date: Sun, 04 Feb 2018 13:20:01 -0800
From: "Kenneth G. Gordon" <kgordon2006@frontier.com>
To: Heath@puck.nether.net
Subject: [Heath] HP-23 power supplies - an idea and some questions.
Message-ID: <5A777901.15147.1147466@kgordon2006.frontier.com>
Content-Type: text/plain; charset=US-ASCII
If one looks closely at the schematic diagrams for the HP-23 series of power supplies, one
notices an interesting thing:
In the first-model HP-23 supply, the AC winding which feeds the voltage doubler which
provides the HV is 268 volts, whereas that winding in all subsequent supplies is 282 volts,
an increase of 14 VAC.
268 * 2.828 = 741 VDC whereas 282 * 2.828 = 798 VDC, an increase of 57 volts.
ALL HP-23 power supplies are "rated" by Heathkit at 820 VDC output, but as is clear from
the info above, this cannot possible be so as far as the HP-23 is concerned. 750 VDC
output is far more likely, and in fact, I have measured it at that voltage when attached to an
HW-101 and in the transmit condition in CW.
In my experience, it has been almost impossible to realize the full output power of a pair of
6146s when using the first-model HP-23 power supply, whereas using the later models, full
power output is easily realizable.
So, I have considered installing a small 110 VAC to 12.6 VAC transformer in the HP-23 with
the 12.6 Volt winding added in series between the bottom end of the original power
transformer's HV winding and ground to boost the HV output closer to the "correct" voltage.
What is holding me back is that, as far as I can see, there would be at least 410 VDC
between that point and the frame of the added transformer.
Now, most modern insulation is rated, according to the National Electric Code, at 600 VDC,
so, if this is so, then that would, it seems, give me an almost 200 volt safety margin.
Even so, I am still suspicious.
Has anyone here attempted what I am proposing, and if so, what was your result?
If not, I'll go ahead and try this out. I have at least two HP-23s so I can afford to use one as
a test bench.
Comments?
Ken W7EKB
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Message: 2
Date: Sun, 4 Feb 2018 15:58:10 -0800
From: "Mike Fitzgerald" <MLF42@Q.com>
To: Heath@puck.nether.net
Subject: [Heath] HP-23
Message-ID: <1UQNoGvir0.ZI9FPe4yLN9@mike-pc>
Content-Type: text/plain; charset="utf-8"
Ken...
Ken....A lot of trouble for a few more watts out of the 6146's that no one can hear anyway....I have made numerous tests asking receiving stations if they can hear any differende when I QRO from 100 to 150 watts. Not one said they heard any appreciable differe
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nce...Just sayin"....
Mike AA7WU
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Message: 3
Date: Sun, 04 Feb 2018 17:11:45 -0800
From: "Kenneth G. Gordon" <kgordon2006@frontier.com>
To: Chuck Moore <wcmoore@verizon.net>
Cc: Heath@puck.nether.net
Subject: Re: [Heath] HP-23 power supplies - an idea and some
questions.
Message-ID: <5A77AF51.6775.1E89C59@kgordon2006.frontier.com>
Content-Type: text/plain; charset=US-ASCII
On 4 Feb 2018 at 18:35, Chuck Moore wrote:
> Why? The difference in output will likely be less than 1dB.
Efficiency suffers at the lower voltage.
Ken W7EKB
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Message: 4
Date: Sun, 04 Feb 2018 17:33:16 -0800
From: "Kenneth G. Gordon" <kgordon2006@frontier.com>
To: Heath@puck.nether.net
Subject: Re: [Heath] HP-23 power supplies - an idea and some
questions.
Message-ID: <5A77B45C.3629.1FC4C92@kgordon2006.frontier.com>
Content-Type: text/plain; charset=US-ASCII
On 4 Feb 2018 at 15:54, Mike Fitzgerald wrote:
> Ken....A lot of trouble for a few more watts out of the 6146's that no
> one can hear anyway....I have made numerous tests asking receiving
> stations if they can hear any differende when I QRO from 100 to 150
> watts. Not one said they heard any appreciable difference...Just sayin"....
>
> Mike AA7WU
You are absolutely correct, of course.
In fact, in order to increase the signal level at the receiver enough to hear a difference, one
must double the output power of the transmitter. 100 watts to 200 watts for 1 db difference
at the receiver.
1 entire S unit (or 6 db, i.e. a power ratio of 4) increase at the receiver requires increasing
transmitter output power from 100 watts to 400 watts. Then another S unit above that
requires 1600 watts. No thanks.
I am not concerned about power output here: to my way of thinking, the lower voltage simply
"isn't right.".
If it was not important, why did Heathkit change the AC voltage from 268 to 282?
Are there deleterious effects due to the lower voltage OTHER THAN power output? I
suspect so.
Screen-grid issues come to mind.
But none of the above concerns me.
So, I still have not gotten an opinion or an answer to my question: is it likely that the 410
VDC across the 12.6 V winding of the added transformer is too much, or is it acceptable?
If no one knows, I believe I'll try it to see. Empirical evidence is always good.
Ken W7EKB
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Message: 5
Date: Sun, 4 Feb 2018 18:00:11 -0800
From: "Mike Fitzgerald" <MLF42@Q.com>
To: "Heath@puck.nether.net" <Heath@puck.nether.net>
Subject: [Heath] HP-23
Message-ID: <1UQNoIZGhF.a6VWWgIovs8@mike-pc>
Content-Type: text/plain; charset="utf-8"
The "reason" that transformer was used might have been that's what was available...A productiuon error perhap, corrected in the later models
Mike AA7WU
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Message: 6
Date: Mon, 5 Feb 2018 02:02:26 +0000 (UTC)
From: Glen Zook <gzook@yahoo.com>
To: "Kenneth G. Gordon" <kgordon2006@frontier.com>,
"Heath@puck.nether.net" <Heath@puck.nether.net>
Subject: Re: [Heath] HP-23 power supplies - an idea and some
questions.
Message-ID: <1073031498.3387663.1517796146269@mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"
Methinks you mean 3 dB instead of 1 dB with an increase from 100-watts to 200-watts.? However, even that increase will not be noted in most situations.
As far as why Heath increased the voltage:? A new power transformer was used in the HP-23A that had dual primary windings for 120 VAC and 240 VAC.? Since a new transformer was being used, Heath went ahead and increased the secondary voltage as well to increase the power on the HW-10X and SB-1XX slightly.? Of course, Heath was never conservative on the power ratings of their transmitters.? Having the slightly higher voltage did allow the equipment to come closer to the power ratings.? However, it has been my experience working on a lot of Heath equipment that to make the power claimed by Heath involved pushing the 6146 final amplifier tubes often to beyond their ratings.
Remember, the original 6146 and 6146A / 8298 were rated at 90-watts for Class "C" operation, 85-watts for AB-1 / AB-2 for SSB, and 67.5-watts for AM (all input ratings).? Heath pushed the tubes very hard for both SSB and AM operation.? Of course, back then, the 6146 was in production and very common.? Therefore, who worried if the tubes did not last as long as possible!
?Glen, K9STH?
Website: <a href="http://k9sth.net">http://k9sth.net</a>
From: Kenneth G. Gordon <kgordon2006@frontier.com>
To: Heath@puck.nether.net
Sent: Sunday, February 4, 2018 7:35 PM
Subject: Re: [Heath] HP-23 power supplies - an idea and some questions.
You are absolutely correct, of course.
In fact, in order to increase the signal level at the receiver enough to hear a difference, one
must double the output power of the transmitter. 100 watts to 200 watts for 1 db difference
at the receiver.
1 entire S unit (or 6 db, i.e. a power ratio of 4) increase at the receiver requires increasing
transmitter output power from 100 watts to 400 watts. Then another S unit above that
requires 1600 watts. No thanks.
I am not concerned about power output here: to my way of thinking, the lower voltage simply
"isn't right.".
If it was not important, why did Heathkit change the AC voltage from 268 to 282?
Are there deleterious effects due to the lower voltage OTHER THAN power output? I
suspect so.
Screen-grid issues come to mind.
But none of the above concerns me.
So, I still have not gotten an opinion or an answer to my question: is it likely that the 410
VDC across the 12.6 V winding of the added transformer is too much, or is it acceptable?
If no one knows, I believe I'll try it to see. Empirical evidence is always good.
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</pre></div>