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

[Kenneth G. Gordon]

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.

Ken W7EKB

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