Post a pic of the unknown choke and are there any numbers on it??
1000 volt rating, you're cutting it close. Most any choke can handle 1KV.
Fred
Hello Fred,
No problem, I can take a few photos and post them.
What confuses me is that there is a build page on the Hammond website (
http://www.hammondmfg.com/clas_xample_ART13.htm) that shows that they used the 193Q choke. Now, considering how I see four transformers in the photo that would lead me to believe that they used the choke in both the LV and HV supplies. I cannot see how they managed to make that work as 1000vdc is on the low end for ART-13 operation and at that point you're right at the limit.
Yo'
With only 1KV on the plates of the 813/811's I should
think there would never be a reason to turn that Down.
However the ART-13 responds well to a good a stiff LV
supply for the driver/Multiplier string. If you do put
a variac on the LV supply you may want to shoot for
something like 450-475 VDC out and you could turn that
down if needed.
FWIW My HB ART-13 supply has fuses for fil/LV/HV
The LV is fused at 3 A and I don't recall ever blowing it.
The fil and HV are fused at 5 A each and they have
never blown either.. I think my HV is just below 1300.
73 es GL
/Dan
Hello Dan,
The HV transformer is rated at about 2000-2500vdc with 115vac on the primary. This is why I use a variac so as to bring the HV output down to something more reasonable!
Thank you for the info on the fuses. I initially bought a 12A variac for just the HV alone. Why I did that I have absolutely no idea. To err is human. I am working with relatively limited space and so if I could free up and inch or two here it would make the rest of the build much more relaxing.
I'll keep that in mind about the LV supply. I suppose I just like having more knobs to turn. To be able to trim the LV supply so as to not to put too much stress on the transmitter is my main reason for doing this.
Single choke? You could be talking a swinging choke= 5 - 25 HY @ 350 - 500 ma or a 10 HY choke @ 350 - 500 ma. Be sure the choke pots out for at least twice the maximum HV setting. There are plenty of old buzzard chokes out there at the festers or on eBay. UTC put out a nice potted choke that would look pretty - would match the circular form factor of the power transformer. Thordarson puts out a nice looking juke box form factor choke. Not sure if Hammond makes one any more.
Al
Hello Al,
Yes, that's it. I would like to use a 10Hy @ 500ma. I have the Hammond 193Q planned for the LV supply since it'll be running at maximum 450vdc and the 193Q is rated for 1000vdc. It's a shame that there aren't any properly HV rated chokes out there in current production. The current choke I have seems to work fine and seems to be stiff enough. I just wanted to have the transformers matching in appearance but if it isn't rated for such voltage then no way will I be using it. I'll keep looking around for an appropriate choke, though, as at the very least it'd be nice to have a choke in there where I know the specifications of it for certain.
HV:
Transformer: 2500vdc maximum (I plan to run the ART-13 at about 1000vdc maximum)
Choke: Unknown (Perhaps around the same inductance as the MV choke? It isn't labeled so I am unable to tell)
Capacitance: 47mfd @ 4500vdc maximum voltage with 100k bleeder resistor
Mike,
Not sure what iron you have for high voltage. Since you want 2500 volt capability, and to also run the ART-13 at 1KV, consider this idea. If the transformer has a 115V / 230V primary, then for the ART-13, run it off 115 volts into the transformer primary configured for 230V. Also consider that with a variac drive, the load off the swinging wiper is stiffest when the ratio is 1:1, or when the knob is at the dot. When throttling down, the line will droop more for a given load current. So uprating the variac from a 3A to a 5A or a 5A to a 7A might be a good choice if you want to throttle way down.
I got an off the wall idea to use instead of a variac. If the transformers are toroidal cores, it would be easy to add more primary turns. As an example, if the primary had 100 turns, then add 10 more (tap), then 10 more (tap), then 10 more (tap.). Then use a four position rotary switch to select the taps (Full, -10%, -20%, -30%). This idea loses merit if the primary turns are a lot more than 100, but is still possible. You would have to wrap in the correct direction though, so try it first with a few turns.
You have a very neat looking shack as seen on QRZ....so where does the power supply fit into the setup?
Jim
Wd5JKO
Hello Jim,
I am unsure if the current HV transformer has a tap for 230. It's a rather large item, though, so I would imagine it very well might.
Thank you for the reminder on the line sag and the need for a sufficiently rated variac. I had read that a while ago and had forgotten about it up until now. The HV transformer is not a toroidal but the LV one is so that idea is very valid.
Thank you for the kind words about the QRZ photo. I need to update that photo as I have really rearranged my station since then but the ART-13 still sits on top of the same rack cabinet. The power supply goes in the empty space in the rack cabinet and the HV transformer and filament power supply are external to the supply
I did see that thread and was impressed at how compact he was able to make his supply.
Finally,
I have heard that putting the choke on the negative side of the HV alleviates the voltage breakdown issue. If this is true, why is this so?
