[Central-Electronics] Solid State Power Supply for 100V

[peter markavage]

I solid-stated my 100V years ago. Found some old and weak tubes with
octal bases, broke the glass, cleaned out the base, epoxy a small perf.
board in it, mounted some 1N-4007's or something similar (bag of 100 for
pennies at a flea market), and plugged it in. Been working ever since. No
variac, no thermistors, no power resistors, etc. Most of my rigs have
something similar.

Pete, wa2cwa

On Thu, 24 Feb 2005 13:47:00 -0600 "Jim candela" <jcandela at prodigy.net>
writes:
> 
> Lyman,
> 
>     The manufacturer states the following, "It is a combination of 
> diodes,
> power resistors, and other circuitry that emulate the warm-up and 
> operating
> curve of the tube type rectifier it replaces. Each model emulates 
> the
> forward conduction resistance curve of the tube type it replaces and 
> also
> has linear in-rush current limiting to simulate the warm-up of a 
> tube
> rectifier, however, it is in the 1 to 2 second range, rather than 
> the 7 to 9
> seconds of a typical rectifier tube."
> 
>     To me this implies he uses suitable diode(s), a series power 
> resistor,
> and a negative temperature coefficient thermistor in parallel with 
> the power
> resistor. My guess is that he uses the copper top as a heatsink for 
> the
> power resistor. Maybe my guess is incorrect. If someone knows the 
> details,
> please jump in and clarify the situation. This is a clever 
> marketing
> strategy, and it will probably work just fine in many applications.
> 
>      One thing concerns me here. The stated 1-2 second warm-up is 
> faster
> than the original rectifier if it were indirectly heated. It might 
> be
> comparable to say a 5U4 which is directly heated, and will supply B+ 
> very
> quickly after turn on. I worry about the power supply electrolytics 
> where
> the surge voltage may be higher than with a vacuum tube rectifier. 
> This
> surge may damage the filter capacitors if too high.
> 
>      I have observed poor power supply performance in rigs like the 
> EF
> Johnson Viking I where the B+ may sag a 100 volts or more with 
> modulation
> (AM). Converting the P/S to solid state really wakes this rig up 
> with higher
> B+, and much stiffer regulation. As for the 100V / 200V I believe 
> the stock
> design is "higher-end" than what Mr. EF Johnson used in the Vikings. 
> I am
> not sure what advantage if any this proposed power supply change 
> would do
> for a 100V. If the surge, or B+ is higher, the filters might be at 
> risk, and
> the 6550 pin 3 (plate) may flash over to ground.
> 
>      If you go ahead to try this copper rectifier, please take some 
> time to
> evaluate stock versus modified performance, and report back to the 
> group.
> 
> Thanks for getting a topic going again,
> Regards,
> Jim Candela
> WD5JKO
> 
> 
> -----Original Message-----
> From: central-electronics-bounces at mailman.qth.net
> [mailto:central-electronics-bounces at mailman.qth.net]On Behalf Of 
> Radra
> Sent: Thursday, February 24, 2005 11:42 AM
> To: Central Electronics
> Subject: [Central-Electronics] Solid State Power Supply for 100V
> 
> 
> I am considering replacing the tube rectifiers, 5U4-GB and 6AU4-GTA, 
> with
> solid state rectifiers.  Weber manufacturers a series of plug-in
> replacements for these tubes e.g. "Copper Cap Rectifiers".  Their
> performance is supposed to emulate that of the original tubes.  
> Refer to
> http://www.webervst.com/ccap.html for more info.
> 
> Has anyone had any experience with these replacements?  Or more 
> generally,
> are there any recommendations regarding use of solid state in the 
> 100V power
> supply?
> 
> Lyman K7LH