Johnson Thunderbolt Power plug.

[ke7trp]

I picked up a Tbolt cheap.  I am going to go through it at some point and if I ever have the room, Use it with my ranger and SX100 for a complete station.  The Tbolt has no power cable.  Any ideas where I can get this twist lock type plug?  If you found one that fit, Would you please tell me the part number so I can order one?

I plan to use it on 240 volt.

Thanks..

Clark

[Pete, WA2CWA]

The mate for the chassis connector, if original, is Hubbell 7565 C Connector Body
This ebay listing just ended several days ago but this guy has 3 for sale: http://cgi.ebay.com/Hubbell-7565C-Insulgrip-3Wire-Twist-Lock-Connector-Body-/180532853246

[ke7trp]

THanks.. I emailed him to see if he has them.

Pete, The manual states neutral wire and two 115 volt lines.  My 220 Volt outlet is ground and two 115 volt hots.  Will this work? Sorry for my igorance about this.

C

[WQ9E]

Clark,

As was common at the time, much of the vintage gear tied neutral and ground together.  The NEC requires ground and neutral to be bonded together at the panel but kept separate until then.  You can either modify the equipment to lift neutral off ground and have separate neutral and ground (4 wire plug) or ignore the newer NEC.

To use the 3 wire plug, you need to connect neutral to the third contact (I assume you are going to run the Tbolt on 240) and since this line is grounded internally neutral will then be connected to ground.

A LOT of vintage gear is still run as originally wired.

[ke7trp]

The 60 amp 240 wall socket is 4 wire.  But the adapter box I built to plug in here, Then provide two 240 volt 20 amp plugs (for linear amps) use 3 wire plugs.  This is Ground and two hots.

Should I just hook this up to that 240 volt 20 amp plug and then plug it into the box?

C

[W2PFY]

usually a a 4 wire socket is for three phase. I wonder why they installed that type of socket? You should be good to go if you have the amplifier wired correctly for 240.

What do they have in there? Two grounds?  If you do have three phase, just use two hots and the ground.

[n2bc]

You need a 4-pin arrangement to support hot / hot / neutral / safety ground.

If it were my T-bolt (and I am not mod adverse at the expense of safety), I would mod the power arrangement on the T-bolt for the correct 4-wire connection.  As I recall, the T-bolt does require some 120V even if wired for 240V on the HV transformer.  Therefore it needs hot / hot / neutral to support both 120 and 240V feeds.  The 4th connection, safety ground, goes to the chassis and should never be wired to carry current.

My 2 cents.

73, Bill   N2BC

[ke7trp]

Ok.  Does the Ground have to be the house ground or can it be my station ground which is an 8ft Copper rod into the earth with a number 6 into the shack?

Its going to be a real pain to rewire all this crap for the Tbolt. The 220 volt 20 amp plugs I have now are all three wire..
Running a new circiut just for this Tbolt is just nuts. If I cant run it three wire or use my station ground, Then I will sell it off and not even bother.  I just thought it would be neat next to the ranger.

 

C

[W2PFY]

Clark, I would continue just like you were going to with the three prong adapter plug. If you want to add a safety ground, you could run a separate wire and ground it to the outside of the amp somewhere. I would hook the forth wire to the house wiring.

Now if it were at my place, I would just go with the three wires and be done with it.

The wire with #6 hooked directly to the back of the amp might serve you well if your going to use an antenna tuner. Good RF grounds are where it's at. Now some people wouldn't agree with what I just said if they are using a bunch of pro audio gear and are running into ground loop problems but that a story for another time

End of story

[WV Hoopie]

Alright already,

The proper care & feeding of a Tbolt can't be that difficult! I'll hazard a guess the back of the Tbolt has the same male end as a Johnson Desk. Leviton still makes the non-NEMA twist-lock female connector. Purchased one not too long ago, along with a standard cloths dryer cord/3wire #10AWG.

Power neutral (white wire) I believe goes to the keyed/sort of L shaped slot on the female side. Your earth ground/8 foot rod (what ever color) connects to the chassis.

73's,
Craig

PS: Just about any good electrical supply business should have it in stock. Take Tbolt with you to test.

ADDED Later: Clothes dryer cord could be RED/BLACK/WHITE maybe RED/BLACK/GREEN

[WQ9E]

Craig,

The connector isn't a problem and shouldn't be difficult to find.  The only issue is whether you want to "upgrade" the older Johnson gear (Desk KW, T-bolt, Viking 500) to meet current NEC.  The original wiring has neutral connected to the grounded chassis in multiple places (at least in the Desk KW).

So you can either rewire, use the ground lead as the neutral return, or have ground and neutral tied together at the transmitter/amplifier.  My personal opinion is that option 2 or 3 is probably less egregious than many of the wiring mistakes and shortcuts commonly made in home and a lot of commercial construction.  From recent reading it sounds like a burning CFL or lightning exploded corrugated gas line is more likely than problems from using a 50's wiring style vintage rig.

[W1ATR]

The 60 amp 240 wall socket is 4 wire.  But the adapter box I built to plug in here, Then provide two 240 volt 20 amp plugs (for linear amps) use 3 wire plugs.  This is Ground and two hots.

Should I just hook this up to that 240 volt 20 amp plug and then plug it into the box?

C

Wait a minute. Are you saying that your NOT using the service neutral that enters the house from the pole, but instead using the house safety ground as the neutral connection in your cords to your equipment??? No this is wrong, dangerous, and you need to correct it. You need two hots and the neutral on the cord from the outlet. The ground to the chassis can be braid, or heavy wire to your station ground.

I got the plugs for my old tbolt and invader 2000 at Graingers. Donno if you have one of those near you or not. My J500 doesn't use a plug as its hard wired to the power supply chassis. Two hots and neutral on the terminal strip and a ground lug on the chassis for station ground.     

[ke7trp]

Sorry for stiring up a bee's nest here guys.   I just dont have the electrical experience for this and that is why I am asking for help

The 240 volt plug on my wall that the electrician installed is 4 prong.  Two hots, a neutral and a ground.

This line powers an SB200, and various other SSB amps that I own. 

This 60 amp plug (Dryer type) has a three wire cord with two hots and a Ground that runs to a dual outlet 220 volt 20 amp style plug for the amps.  This is two hots and a ground.  The neutral is not used and stops at the wall. It does not carry down to the amps.

The only oddity here is the Tbolt as it has two hots and a neutral.  The ratio is 50/50.  4 people saying hook the Tbolts neutral to the ground and go on.  4 saying you cant do that and you need four wires.  I am just confused.

w1atr..  Can you unplug your Tbolt and tell me the NEMA number on that plug so I can go and get one or order one? It seems nobody is willing to simply tell me what they used.  I had a Friend bring his Desk KW cable over and it wont fit. The Desk KW plug is MUCH larger.

Thanks guys

C

[Pete, WA2CWA]

I told you in my first post the type of connector that is used with the mate (if original) in the Thunderbolt.

[W1ATR]

Yes Pete, thats it. I just checked mine and it's this one.

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=7565+c&op=search&Ntt=7565+c&N=0&sst=subset

[W1ATR]

And here's one for less.

http://www.onestopbuy.com/leviton/7565-C-2655.asp

and another,

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260494397837&rvr_id=&crlp=1_263602_263622&UA=WXF%3F&GUID=dac4270e1270a02661f16b91fffa48e9&itemid=260494397837&ff4=263602_263622

So far we're down to 17 bucks. Maybe I'll find a free one if I keep looking haha.

[WV Hoopie]

Yes, we have a winner! The connector issue is solved. I don't believe a Home Depot or Lowes will carry them. Another faster option is a local electrical supply business.

As to 3 wire or 4 wire; for years clothes dryers were a three wire appliance. Wonder how may wifes were zapped? Ain't my ball of wax, but my 500 & Desk are wired as a 3 wire boatanchor same as it left the factor, plus a good heavy ground wire from chassis to ground rods outside the shack.

Clark, some of the stuff in the tbolt runs on 120VAC. Most likely fans, low voltage transformers, filament transformers, maybe a relay, etc. The 240VAC might be just for the HV plate voltage, I don't have a skizmatic for the tbolt.

Craig,

[WQ9E]

Clark,

The fans used in the T-bolt are the same ones used in the Desk KW and Viking 500 and they are prone to shorted motor windings.  They make a lot of smoke when this happens but there shouldn't be any collateral damage.  But I would suggest properly lubricating the bearings before you put it into service to reduce the chance of failure (due to excess heat from dragging bearings).  You may need to remove the fan assembly to get the front bearing.  I use a hypodermic loaded with the same synthetic oil required for the purge blower motor in my central heating system.  Also remove the dust/dirt on the fan assembly.

I would leave it wired as is and connect a safety ground to the chassis.  Only the plate transformer runs off 240 volts; the fans, filament, and screen supply transformers are connected for 120 volts.

[ke7trp]

Ok. So you cant run the Tbolt on a 3 wire system.  I will just ditch the thing.  I am not going to pay an electrician to run a seperate line from the box for this amp alone.

Thanks for the links on the connectors!  I was looking for the nema number of the modern part so I can just go down and buy one. 

Thanks alot guys!

[WV Hoopie]

Clark,

You CAN run the tbolt on a 3 wire system. A separate heavy ground wire from a 8 foot ground rod is connected to the chassis.

Nothing more is needed, simple.

Craig,

[ke7trp]

I got three emails stating you cant do that and I am going to either burn the house down, Shock and kill myself and or the Tbolt will have 240 across everything and blow up.. LOL!

I am going to try it.  I dont see any reason why this thing cant run on three wires. I ordered that plug.  It should be here next week at which point, I will fire it up

Its my Bday today!  Going to try to get some AM in on 40 this morning.


C

[WQ9E]

Happy Birthday and don't blow yourself up 

You will be fine with a 3 wire system plus safety ground connected to the chassis.  Notice all of the three wire Johnson gear still around?  It didn't blow up or burn down with the house or it wouldn't be around still.  There is a much greater chance that your laptop battery or CFL will blow up before you have a problem with the Thunderbolt.

I have a Desk KW, Thunderbolt, 6N2 Thunderbolt, and a Viking 500 that are all connected as originally designed (along with an additional ground wire to the chassis). 

[WV Hoopie]

Clark,

When you get ready to wire the plug: Using a volt meter, hot to hot should measure around 240VAC. Either hot to neutral should measure around 120VAC.

Look at the skizmatic: It should become clear how the plug, new cord, etc.; will mate up with the male connector on the back of the tbolt. Also check out the color of the screws in the plug, betcha two of them are gold in color, hot connects to these. Only one of the screws will be silver in color, neutral connects here.

Sort of like cutting a piece of wood, measure twice, cut once.

Craig,

[The Slab Bacon]

Or just simply reconfigure the jumpers under the chassis and run the whole thing on 120. Short sweet and simple!!

I've done that with my T-bolt years ago!!

[n2bc]

All rewiring for 120V does is make the HV tranny look  like the other 120V components.  Neutral will still be connected to the chassis - doesn't make it much worse (there will be more current flowing on the neutral however), doesn't make it any better (safer).

You had best hope that the neutral and safety ground are wired properly all the way back to the entrance panel. 

The 'right' fix is still to separate neutral and safety ground.   

If you are not going to do that, make sure your outlets & wiring are proper. 

Also, be darn sure that everything else in your shack - or at least within reach of the t-bolt - is always securely bonded to safety ground.

It is such a bad practice to knowingly connect the chassis to neutral.  With a roomful of boatanchors, worked on by who-knows how many people with who-knows what skill levels.....   bad, bad idea....

73, Bill  N2BC