[Boatanchors]Heath HP-20 versus HP-23

[Philip B Atchley]

Rich et al,
This is pure conjecture (based on sound scientific reasoning) as I don't
presently have a HP23 and HP-20 here to compare.

HP-23:  Current wise the HP-23 is a much heavier duty power supply, being
designed to handle two 6146 (or similar) Finals while the HP-20 is
designed for rigs with one final.  Heath states the HP-23 will output 800
Volts without a load, dropping to 700 Under load (two finals).  Hence, I
interpolated that it'd probably put out something like 750 Volts with one
Final running on it (the Elmac).  It seems that the "later" rigs also
pushed their finals a little harder Voltage wise (up from the typical
500-600 Volts of the earlier rigs to 700 Volts or so).  This perhaps to
either get more power output or because the newer rigs were mostly SSB
with NO AM plate modulation like the Elmac and other rigs of the earlier
times had.  I suspect the modulators of the earlier rigs might "break
down" under 700 Volts or more.  

HP-20:  This is a lighter power supply intended to run the older rigs
running a single 6146 or similar final, often with a Plate Modulator.  In
this supply Heath doesn't seem to say, but I suspect that under "key up"
the Voltage may rise to well over 600.  However, since the supply is
designed for less current (single final), it's transformer is most
certainly wound with a lighter gauge wire, both in the secondary and the
primary windings.  This would lead to higher resistance, causing a
greater Voltage drop under load, bringing it down to the stated 600 Volts
or so.   

Does all this make sense to you?

 
73 de Phil KO6BB
REAL Radios "Glow In The Dark".
 
RX 1:  Hallicrafters SX-71 (circa 1955).
RX 2:  Grundig YB-300 digital (doesn't glow, spotting set ONLY).
Antennas: 65' sloper, 1/2 size G5RV Inverted Vee,
                 15M Inverted Vee, Hustler 6BTV Vertical.

On Tue, 22 Jun 2004 16:13:13 -0400 Richard Post <postr at ohiou.edu> writes:
> Phil's note on powering an AF-67 triggered a question for me.  I was 
> 
> given a Swan 175 monobander transceiver.  Its manual has 
> instructions 
> for modifying a Heath HP-20 for power supply.  Don't have an HP-20. 
> 
> Do have HP-23. The schematic for the HP-20 shows a transformer 
> secondary AC voltage of 260 and the HP-23 series have a secondary AC 
> 
> voltage of 268 according to their schematics.  However, the HP-20 
> schematic shows its DC out at 600 volts while the HP-23 shows 820 
> volts.  Both use a voltage doubling circuit.  The HP-20 has a 
> slightly larger (lower resistance) bleeder.  My question:  Is the 
> HP-20 rated at load versus the HP-23 rated at no-load?  Multiplying 
> 
> both the AC outputs by 2.8284 results in 735 for the HP-20 and 758 
> for the HP-23?
> 
> What am I missing in this picture?
> 
> Thinking of using the HP-23 for the Swan.
> 
> 73,
> Rich
> 
> Boatanchor Pix
> 
> <http://www.qsl.net/kb8tad>
> 
> 
> 
> 
> At 7:35 PM +0000 6/22/04, Philip B Atchley wrote:
> >Hi all,
> >Elmac AF-67:  This transmitter also belongs to Don (W6LRG) and 
> hasn't
> >been put on the air since he acquired it, primarily due to lack of 
> a
> >suitable power supply.  He has an extra Heathkit HP-23A (he has 
> lots of
> >Heath stuff) that I'd considered trying to modify for use with the 
> AF-67.
> >  After lengthy consideration I don't think that's the way to go.  
> It
> >would require a bucking transformer to lower the 750-800 Volts down 
> to
> >600 or less, THEN an additional transformer for the AF-67 
> filaments.  I
> >will probably try to acquire either a Heathkit HP-20 (which has 
> ideal
> >Voltage rating for the AF-67) or the Elmac PS-2 supply , any 
> condition
> >and overhaul/repair as required.
> >
> >THEN, after getting the Elmac up and running I'll be a position to 
> do
> >actual comparison tests between the two transmitters for things 
> like
> >stability, key clicks, ease of tuning, audio etc.
> >   
> >73 from the "Beaconeers Lair",
> >Phil, KO6BB
> >

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