It's not the capacitor on phase A.  Oh pooh. Now I have to look for zebras rather than horses...

Yes, I am aware of the basic motor physics ;) That "about a second" is with a stiff supply. Mine is apparently not stiff enough <that's what she said> :D

My original plan was to acquire a 618T with the 400 Hz three-phase supply - usually much cheaper than the 28 vdc or the 400 Hz single phase versions. But this inverter is becoming a real white elephant. It would be running all the time, not PTT like the ART-13.

Anyway I am tempted to go buy a pair of car batteries and find out, just because I'm stubborn that way! (My two "ARC-5" receivers have their dynamotors, but I only run one at a time, and the 28v supply I built with a handy Stancor RT-204 transformer has no trouble).

Charles, WB3JOK/0 since '76

No, just a an Ames (Harbor Freight) 80 buck multimeter with a clamp on AC or DC ammeter.

Peak current is always at initial 0 RPM, as the motor winds up the counter EMF brings the current down in about a second. Basic

DC motor physics.  Considering the instrument pedigree I take no responsibility for the accuracy of the reported result.

As an alternative to floating batteries on the output of a DC supply, one could implement a step starter circuit, but you would need

some hefty dropping resistors and contactor relays.  Wouldn’t lend itself to quick PTT operation on voice.

Chris AJ1G

Stonington CT

Sent from my iPhone

On Feb 26, 2022, at 15:38, Charles <[email protected]> wrote:

Thanks, there's a data point of 5 times the nameplate.. What was the decay time of that 160 amp peak (did you use a scope)?

If I HAD a couple of spare car batteries I'd certainly try them ;) but have you seen the prices lately? they start at $55 plus core plus tax at Wally World...


On 2/26/22 13:37, Christopher Bowne wrote:

I’ve measured the peak inrush current on my ART-13’s DY-17A dynamotor,  it was a nominal 160 amps.  Just float a couple of 12 batteries across the output of your supply, make sure that they are fully charged and full sized automotive or deep cycle marine type, small one may not deliver enough peak current to preclude tripping the output breaker in on your high current supply.

Chris AJ1G

Stonington CT

Sent from my iPhone

On Feb 26, 2022, at 13:57, Charles via ARC5 <[email protected]> wrote:

I am sure I would have no trouble starting a DY-17 with a 33 amp full load rating. This beast is 3.5 times that full load draw and consequently any surge current would likely also be 3.5 times that...

Anyway I am going to investigate shorts on the AC side, and my prime suspect is the (noise reduction?) capacitor on A phase. Hope it's not the armature. It does have a repair request tag from the 80's or 90's (don't remember at moment) and an unreadable "Serviceable" tag. The electromechanical regulator (carbon piles!) will get a look after I check the cap. Something else I have no experience with.

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