[ARC5] AC Power Supplies

[J Mcvey]

Very nice build on the dyno platform!I have a badly constructed  homebrew stand-alone that I found at a hamfest last year which came with the receiver.They used two 12V filament transformers. one was used to feed the filaments and the OTHER transformer wired seconday to secondary to provide ISOLATED B+ AC .You will get get approx 169VDC with half wave rectification. That way you get around finding custom transformers... and you won't get electrocuted with direct line rectification.( A REAL BONUS!!!)

I use dynamotors rather than replacement supplies, so I never bothered to clean up the bad wiring under the otherwise nice looking supply made with an open bottom chassis box.
 

    On Tuesday, December 27, 2016 1:55 PM, Dave Merrill <r390a.urr at gmail.com> wrote:
 

 On Mon, Dec 26, 2016 at 8:23 PM Brian <brianclarke01 at optusnet.com.au> wrote:

Hello Dave,Very nicely made.My first concern is for the stress on the HT secondary winding at start-up, with direct feed to 94 uF of filtering. For trannie longevity, I would put small resistors between both filter caps and one between the rectifier and the first filter cap. 100 Ohm each will only drop the output HT Voltage 8 V. For a commercial example, Tektronix did this with all their solid-state, linear power supplies on their 500-series of CROs.

That's a good suggestion and I will add it to Build 2.0 
My second concern is those 20+ year old capacitors; electrolytic capacitors like running close to their rated Voltage. So, if they’re falling over – low C, high ESR – I’ld replace them with ones rated at 180 to 220 Vdc wkg.

The code date on the capacitor can is 6704 so it is almost 50 years old!  Still working - I measured the ripple at .48 mV with no load and 2.2 mV at 50 mA load.  Since I'm a ham I used what was within easy reach, but I'll remember to replace it with a more suitable working voltage unit at some point. 
Dave Stinson, AB5S and I – and many others - will confirm that Command receivers work very well with 160 Vdc HT.Your 22k bleeder is a very good choice – hardly affects the output current available, and gives a 1/e Voltage drop every 2 s. Safe.

Good to know I got something right :-)
73, Dave N9ZC 
73 de Brian, VK2GCE. On Tuesday, December 27, 2016 12:53 PM, you showed: Here are some photos of a power supply I built on a DM-10A base 20+ years ago.  I don't recall where the transformer came from but it had both 6.3 and 24 volt filament windings so I allowed for both.  Cap is a dual section 47 uF @ 400 VDC connected in parallel.  Full wave bridge with a 22K bleeder resistor.  Produces 165 VDC @ 40 mA. There is a PC-8417 transformer with similar filament specs and 220-0-220V on eBay now - item 371821125244 (toober is the seller). 

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