The AM Forum

I have seen several examples of ART-13 power supplies using bridge rectifiers with output capacitors.  These seem to work just fine for their owners.

I am in the process of building mine and wish to keep it as small and cheap as possible.

I have the 28V section of the supply working after upping the capacitance to 10000 uF. 

I see ~2Vpp of ripple on this supply and have been going around and around looking into chokes etc to fix it.

Perhaps I don't need to fix it?  Should I be worried about hum?  Hmm, my HB 813 rig has its filaments power with AC!  There is a tad of "ripple" there...  I get "broadcast quality " reports on that one too....

Do I need to have chokes on the HV, either the 1050VDC or the 400VDC?  Right now I have 24uF on the HV...

Bottom line is that I would like to leave it as is and forgo the chokes if people have had good luck with that setup.

Thanks

Rich

 The 1940s Surplus manual uses a 10mh choke rated at 10 amps and a 2000uf cap. I would try a larger cap if you don't want to use a choke. Make sure you have a bleeder resistor across the cap.

73 de Gary,KF9CM

I'm going by memory from the 1960's when I was in high school and running an ART-13. In those days, I used an old selenium bridge rectifier stack and an output capactor of 10,000mf. I couldn't find a choke.

I didn't have a problem with hum.

I'm working on an ART-13 supply right now.

Using that simulation program I post a link to on your other thread, putting a 5mH 10 amp choke in a choke input configuration (with a 34 volt transformer) I end up with 28VDC and less that 1v ripple. I'm pretty sure that would be good enough. The choke cuts the ripple in half.

But, it happens I have the choke, so I will use it.

For the MV (400v) supply I plan to use a choke input filter with a 460-0-460 volt transformer. The simulation shows very little ripple with 40mf output cap. Plus good regulation.

For the HV (1250v) supply I plan to use a 980 v transformer with a capacitor input filter. With that one, I plan to use a 7 mf input capacitor, an 8 hy choke, and a 26 mf output cap. That also gives me very low ripple on the simulation.

(The oddball capacitances happen to be what I can get from my junk box).

Using a capacitor input choke PI filter on the HV supply gives much lower ripple that just using a capacitor filter alone without the choke.

Plus I have the suitable chokes, so I figure I'll use them.

I'm looking forward to getting this thing built and see how it compares to the simulation program.

Dave