[Heath] HP-23 power supplies - an idea and some questions.

Mon Feb 5 11:12:44 EST 2018

And increase of power, times 2, which going from 100-watts to 200-watts represents, is a 3 dB increase.  The formula for a dB is 10(log).  The logarithm for 2 (twice the power) is 0.30103.  Therefore, twice the power is 3 dB.  However, at the receiver, the voltage increase is not 2.  It takes a 6 dB increase in voltage for twice the voltage.  For a 2-times increase in power, the voltage, at the receiver will increase by 1.414.
Here is an article, from my website, that explains why this happens:
 http://nebula.wsimg.com/87fa72d0e2a5447f6496b4a6476ef1df?AccessKeyId=D1250C433DB440D6B60D&disposition=0&alloworigin=1
As for using the 8032 in place of the 6146A / 8298, I do that all the time in equipment that utilizes a pair of 6146 tubes with the heaters ("filaments") wired in series for 12-volt operation.  You can also use the 6883 which is the 12-volt equivalent of the original 6146.  The 6883A / 8032 is exactly the same as the 6146A / 8298 except for the heater voltage.  The 6293 is the pulse modulator version of the 6146A / 8298 (has a 1000-watt pulse input rating) and those tubes, when run at the same level as the 6146, can last up to 10-times longer, certainly at least 5-times longer.
Here is the article on the 6146 family of tubes that has appeared in 73 Magazine, Electric Radio, Collins Signal, and several European amateur radio publications:
http://nebula.wsimg.com/e7364f5298b88b460a668216b4be5946?AccessKeyId=D1250C433DB440D6B60D&disposition=0&alloworigin=1

Having an input, for a pair of 6146 or 6146A / 8298 tubes for CW, of 180-watts is within the maximum ICAS ratings (RCA ratings).  However, for AM operation the maximum rating, again for a pair of those tubes, is only 135-watts.  The Johnson Viking II is the only popular transmitter that was rated at 135-watts input for phone operation.
The Heath DX-100 was rated at 125-watts OUTPUT for phone.  Assuming an efficiency of 70%, that means an input of right at 180-watts.  This exceeds the ratings by 45-watts or 33.333%.  The rating for CW is 140-watts output which, at 70% efficiency means an input of 200-watts.  That is a bit better because it is only 20-watts over the maximum ICAS ratings or about 11%.
Heath, for the TX-1 Apache, got the ratings a lot closer but still a bit too much for phone.  The Apache did not have a power output rating.  Instead, the Apache was rated at 180-watts input for CW and 150-watts input for AM.  The AM rating is still over the maximum rating by 15-watts which, again, represents about a 11% margin.
The maximum plate dissipation for the 6146 and 6146A / 8298 is 25-watts.  Technically, Heath only exceeds this by 5-watts per tube or 20%.  However, 20% is a lot and, in the real world, 70% efficiency is not going to happen as the tubes "age".  The efficiency will drop, over time, and that means when the same power is run, the actual plate dissipation will increase because the input power has to be increased to get the same output power.
Collins rated the 32S-1, 32S-2, 32S-3, 32S-3A, KWM-2, and KWM-2A at 100-watts output for 80, 40, and 20-meters, 90-watts output for 15-meters, and 80-watts output on 10-meters.  
Reducing the power 10% from the maximum ratings generally will increase the life of the tubes by a factor of about 3 and reducing the power 20% from the maximum generally will increase the life of the tubes by a factor of 10.  Even a 20% reduction will almost never be even noticed by the operator on the "other" end of the QSO.  However, the tubes will definitely know the difference!  Considering the fact that the tubes are becoming less, and less, available, at least to me, doing whatever possible to increase the lifespan is certainly a good thing.
Since today's equipment ratings are in power output, many operators do not realize that, for many "boat anchor" transmitters, the power rating is for input, those operators try to get the rated input power as output power and that causes all sorts of problems! Glen, K9STH 
Website: http://k9sth.net

      From: Kenneth G. Gordon <kgordon2006 at frontier.com>
 To: Glen Zook <gzook at yahoo.com> 
Cc: Heath at puck.nether.net
 Sent: Sunday, February 4, 2018 10:11 PM
 Subject: Re: [Heath] HP-23 power supplies - an idea and some questions.

On 5 Feb 2018 at 2:02, Glen Zook wrote:

> Methinks you mean 3 dB instead of 1 dB with an increase from 100-watts to
> 200-watts.

I'm not sure that is correct, Glenn. Bb increase for power is 4X not 2X. I'll have to do some
figuring to see. DB being logrithmic.

>  However, even that increase will not be noted in most situations.

Of course not. However, as I recall it, Alexander chose 1 dB as the smallest difference one
could hear by ear.

> 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.

Seems to me to be unnecessary...unless it was for "advertising" purposes.

>  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.

Well, perhaps, but first of all, I prefer to consider the dissipation ratings of the tube in
question, rather than output. And secondly, any Heathkit HW/SB rig with two 6146s should
be able to output 110 watts on 80, and when properly aligned, they do...with the later power
supplies anyway.

> 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.

I don't consider 180 watts input for a pair of tubes rated at 90 watts input to be pushing the
tubes "very hard".

>  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!

Well, my SB/HW rigs are very reliable when used properly and kept aligned.

BTW, what do you think of the 8032 for use in our rigs? Filament circuits would have to be
wired for 12.6V though. Isn't the 8032 simply a 6146A with a 12.6 V filament? Motorola
would know. ;-)

I just bought 8 NIB.

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