Here? is? how? I? did? my? external step? start.? ?I? used? a? ?8"? x 8"? x 4"? electrical? box....with? knock? outs.
240? vac? line, using 10? gauge? wire, is hardwired? from? 2? pole? breaker? in my? 100A sub panel..to? 8x8x4? box.? 240? power? cable? from L4PS? also? hardwired? to same? 8x8x4? box.?
Garden? variety? DPST? 30A? relay,? (P+B,? deltrol,? etc)? is? installed in? 8x8x4 box...and used? to? apply? the? 240? vac. (Drake RF? deck? ON/OFF? switch? left to? ON? position).
2nd? relay,? SPST,? also? 30A,? used to? shunt? the? 25? ohm @ 100? watt? wire? wound.? Wire wound? mounted? on? standoff's.? So? 2 x relays + resistor mounted in? the? 8x8x4? box.?
Small? control? cable wired? from? 8x8x4? box? to? desk....? terminating? in a small? mini? box.? Mini? box? has? 2 x? miniature? toggle? switches on it.? ?One? toggle? per? relay? coil.
Toggle? #1? applies? 240? vac.? After 3-5 secs,? toggle? #2 is activated,? shunting the? 25? ohm resistor.? Dead simple.? ?Step? starts both the? B+? AND? the? fils....at the? same? time.?
ZERO? arcing? when? either? relay is activated.? ?It's? just a? manual? step? start? setup.? 250 Volt? MOV? across SPST? step? start? relay? contacts.? (130 Volt? MOV? across? coils? of both? relay? coils).?
If switching? from? 2650 vdc....down? to? 1900? vdc,? no? problem.? ?But? when? switching back? from? 1900? to? 2650? vdc, the? ?toggle? #2? is? 1st? activated....? putting? the? resistor? back inline.
Toggle #2? ?then activated,? again? shunting? resistor.?
240? vac /? 25 ohms? = 9.6? amps? =? ?2304 watts...when? T=0.? That only? last a? few? Msecs? as? caps? charge? up.? ?(The? harbach board? uses a 22 ohm,? 25 watt cement? resistor).
(I? have? also used a? 0-15? sec? adjustable? timer? to apply the? 120 vac? to the? coil? of the step start contactor....? but? that's? only? on? Big? ?HB? B+? supplies,? and ONLY? the? B+? supply? is? step? started. The? fil? from? the? tube? has it's? own? step? start /variac? combo...? bigger? metal? triodes).
Jim? VE7RF??
