Johnson Thunderbolt Power plug.

[The Slab Bacon]

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

that is easily enough done while your reconfiguring it. It just involves moving a couple wires around in the power supply. Takes all of 15 minutes to do it. While you have it out of the case gives a good opportunity to give EVERYTHING ELSE a good thourough inspection!

Unless you want a T-bolt just for collector value, it is one of the lowest power to weight amps out there and really not worth putting in all of that work and the cost of a hernia truss for an amp that is only gonna give you 150-200max watts carrier.

[W2PFY]

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!

R U still alive

[Sam KS2AM]

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

As a famous AM'er once said.  "Are you on narcotics ?"   

God Bless Mel Gibson ......

[W1ATR]

Yeah he can walk it right in to the supply house up on his shoulder like one of those giant 80's ghetto blaster radios.  

[Pete, WA2CWA]

Actually it's very easy to remove the AC receptacle from the back of the chassis and the wires attached to it. That's what I took when I went to the local electrical supply house. He looked at it, mumbled something to himself, walked to the back, and came back with three matching plugs (at one time I had two HF Thunderbolts and a 6N2 Thunderbolt).

[ke7trp]

I got the plug off the net.  I guess I will have to rewire the 240 volt line to the shack.  What a pain.  Every other amp, and transmitter I own uses 3 wires.

I am going to match the Tbolt up to my Valiant and or ranger once I have a large enough shack to hold it.

C

[WV Hoopie]

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

As a famous AM'er once said.  "Are you on narcotics ?"   

God Bless Mel Gibson ......

My Junkston desk weighs in at about 400 lbs. Not that stupid, took the plug off of the desk and then to an electrical supply house. Piece of cake

Craig,

[Pete, WA2CWA]

I got the plug off the net.  I guess I will have to rewire the 240 volt line to the shack.  What a pain.  Every other amp, and transmitter I own uses 3 wires.

I am going to match the Tbolt up to my Valiant and or ranger once I have a large enough shack to hold it.

C

I ran my Thunderbolt off 120 AC for years without any problems. It's still wired for 120 today. All my linears run off 120 AC.

[ke7trp]

Its ok.. I want to run this in my new ham shack with a valiant and ranger sitting next to it. I want it on 240 volt. I have a feeling its going to run alot better on 240 and thats why these amps have rep for low power. People plug them into wall sockets at 120 volts.  Its not something I am going to use all the time. Its just an amp that I have wanted for years and I finally go it

C

[The Slab Bacon]

Its ok.. I want to run this in my new ham shack with a valiant and ranger sitting next to it. I want it on 240 volt. I have a feeling its going to run alot better on 240 and thats why these amps have rep for low power. People plug them into wall sockets at 120 volts.  Its not something I am going to use all the time. Its just an amp that I have wanted for years and I finally go it

C

Clark,
         It would be OK paired up with a ranger, but you wouldnt accomplish much pairing it to a valiant. Paired to a valiant would be a waste as the t-bolt is only good for somewhere around 150-200w of carrier out and a barefoot valiant can do 125 or so.

[ke7trp]

On 240 its going to do more then that.  300 should not be a problem.  My Valiant has adjustable Screen volts using a 6aq5. I thought of using a T connector and putting a Cantenna on the floor to help reduce the ranger and Valiant.

C

[The Slab Bacon]

On 240 its going to do more then that.  300 should not be a problem.  My Valiant has adjustable Screen volts using a 6aq5. I thought of using a T connector and putting a Cantenna on the floor to help reduce the ranger and Valiant.
C

Ok, on 240 it will do 201 watts    Their good for somewhere around 6-700w PEP out.
Do the math, divide by 4 for AM carrier to have the headroom for modulation peaks.

The biggest problem with them is the low (2000v) plate voltage. and the plate tank wont take much more without zorching over.

the only hope is to change the tubes to the unobtanium PL-175s and kick up the screen voltage. Basically a big waste of time. If you run it at 150w of carrier with good peaks, you can beat the piss out of it forever, but thats about it.

[Pete, WA2CWA]

Frank's on the mark with this rig. Big brute tank-looking rig but, on AM, works like a little pussycat with little to no claws. On SSB, it gives you some leverage over a SB-200 linear, but with a SB-200, you can carry it under your arm if you have to move it from place to place.

[ke7trp]

Hmm..I think you guys ran them on 120 volt.  I talked to a few people since I got the thing and they told me that with SS rectifiers and 240 volts. The amp comes to life and will do 300 am. There are loads of pages showing 2400 to 2500 volts on the plate in this config and there are saying 1200 watts out pep.  I see no reason it wont do 300 watts on AM.  The valiant all the way up does 130 watts with about 450 pep so its going to double the power of the valiant and take a ranger way up. Its rated for 800 watts input on AM. So thats near 300 watts.

I really just want the thing to sit there on the table with my johnson gear. I wont use it much. But should be a nice piece for the collection.  Time will tell and I will test it out.  I am into this thing right so its worth it to me to at least try!  Most of these where snatched up by Cbers so I feel lucky to have a decent one here.

C

[Pete, WA2CWA]

When I received my first Thunderbolt, it had solid-state rectifiers in it and was wired for 220V AC so my initial testing was done at that voltage. Even at that, plate voltage was no more then around 2250 volts. Don't remember what the AC line voltage was at the time. Also used an external measuring voltage meter to read plate voltage.  In the AM mode, plate current should be no more then 375 ma if you follow the manual. I remember trying this thing on the air and pushed the plate current to about 400 ma; line voltage was about 232V AC. Blew apart one of the coarse loading caps and bubbled one of the six electrolytic capacitors in the HV power supply. I think the coarse loading caps are rated at 2500 volts. I was driving it with a Ranger.

[WV Hoopie]

Clark,

Run the beast on 240VAC. Then remember that 800 watts AM rating was when power was measured as INPUT. So you are looking at 800 watts PEP input. Do the math and 200 watts of carrier output might be a MAX (about) figure.

Still a good pair of shoes for the Ranger

Craig,

PS: Something else I've noticed with the NorthWest group on 3.870; using a SB-610 and watching a trapz pattern will get the driver & linear loaded correctly and sounding gud.

[ke7trp]

Ok. I was also thinking of using it with my BW 6100 for vintage SSB net.  Also, If I can get one of you guys to help me with this CE20v. I could use that. 

I thought the 800 watts AM was input rating for carrier.  I dont think they used PEP back then.  If it was rated like the rest of the johnson gear then it works out to be 250 to 300 watts.  Either way, Its going to spice up the ranger and look neat sitting there on the table!

C

[WV Hoopie]

Look at the ads in the old ARRL handbooks, even the Johnson KW Amplifier had a 2000 watt PEP input rating if used in SSB service. The early desk ran AB1 in the SSB mode, figure the efficiency. Later ones were modified by owners, (if they purchased the kit from Edgar) to run AB2 with 4-400A's to make more smoke as a linear.

Craig,

PS: For grins & giggles, I broke out some of the advertising claims. The Ranger was said to be able to run 65 watts input on AM. Who knows what comes out the other end. Then going to the claims of the Tbolt; using a Ranger as the driver, power increase is 5.7 times. For what it is worth.

[Pete, WA2CWA]

They mention "PEP" in the first paragraph of the manual for SSB rating. Also, make sure you add an external relay to switch between the operating bias and the blocking bias. This is also covered in the manual. The manual is pretty specific on tune up procedures depending on the mode. I would follow that closely until you get the hang of what they're telling you to do and the various meter readings. If your Thunderbolt came already wired for 220V AC, you probably don't need to do any internal wiring but, if it was used on 120V AC, you're going to have to rewire several primary leads on several transformers. The bias-screen transformer and the filament transformer only run on 120V AC. See page 2 of the manual.

[ke7trp]

Roger that, Pete.

C

[w5omr]

Its ok.. I want to run this in my new ham shack with a valiant and ranger sitting next to it. I want it on 240 volt. I have a feeling its going to run alot better on 240 and thats why these amps have rep for low power. People plug them into wall sockets at 120 volts.  Its not something I am going to use all the time. Its just an amp that I have wanted for years and I finally got it

Be careful what you ask for... you just might get it :-)

But, let's be realistic...  that thing has a pair of 4-400's?  Ok.  Regardless of what tubes are in the final, the math will eb the same.  Easy as P=IE! 2000v @ 300mA = 600w DC Input.  Figure efficiency of the Class B circuit at 65% (theoretical, 60% more real-world number'ish) = 390w out.  That's roughly 100w of carrier, if you use the thing as an AM Linear.

Since most reports I see everywhere are that the Thunderbolt produces 750w out in CW, I gotta say that it's more than likely to be running a bit above a kW DC input. (2000v @ 500mA / 2500 @ 400mA - somewhere in there).

So, whatever amplifier you're using, use the 25% figure/rule/law/whatever....  Whatever the total of the linear amp is, figure 25% of that for carrier.  If you get 1000w Carrier out of it, then 250w is where the carrier level should be set for AM.  Watch your scope so you don't over-modulate.  Same is true for solid state devices.  If your ricebox produces 100w carrier output, then reduce the carrier to 25% of that (or 25w) and adjust the alc until it doesn't increase with audio peaks, or reduce the audio gain -just- to the point where you're no longer driving the ALC positive.

If you plan on running the Thunderbolt at 300w of carrier, and then try to fully modulate that signal, then I'm afraid you'll be disappointed in the signal reports.  Overdriven, distortion, "fuzzy" sounding...  Take heart, though... reducing the power output back to 1/4 of the output of a Thunderbolt, is only going to knock you from 300 to 200w, and that's less than 1/2 of an S-unit, and the signal would then be -clean- (as long as it wasn't over-modulated).

73 = Best Regard"S",
-Geoff/W5OMR
(/m5 Baja Spring, TX)

[The Slab Bacon]

Clark,
        just FWIW, the primary on the plate transformer is just split into 2 windings.
Series for 240v and parallel for 120v. The outpoot voltage is not gonna change much other than whatever voltage sag you get at the 120v outlet from the heavier current draw on 120. It should make little or no difference in the outpoot of the amp unless you have bad line sag.

As far as replacing the MV rectifiers with solid state, that will also NOT make much / any difference in the outpoot as the voltage drop across the MV rectifiers is only a couple of volts. You could actually use 866s at 12 or 24v and they would work well (I've experimented with it). The big advantage of solid stating them is that you eliminate the zorch over problems if you don't let them warm up long enough to vaporize all of the mercury in the bulb.

You might gain a little something by solid stating the smaller rectifiers in the screen supply. But then change the VR tubes to allow for the higher screen voltage.

Be sure to buy a really good hernia truss when working on it!!    

Hmm..I think you guys ran them on 120 volt.  I talked to a few people since I got the thing and they told me that with SS rectifiers and 240 volts. The amp comes to life and will do 300 am. There are loads of pages showing 2400 to 2500 volts on the plate in this config and there are saying 1200 watts out pep.  I see no reason it wont do 300 watts on AM.  The valiant all the way up does 130 watts with about 450 pep so its going to double the power of the valiant and take a ranger way up. Its rated for 800 watts input on AM. So thats near 300 watts.
C

[WQ9E]

My Thunderbolt is paired with a Johnson Pacemaker which, to me, is the perfect match.  It does a fine job on SSB and CW while providing a worthwhile gain on the fairly low power AM output from the Pacemaker.   It would be even better with a low power controlled carrier rig.  For a worthwhile gain from a Valiant you would want something with three 3-500Z tubes or the equivalent backed by a serious power supply and plenty of airflow.

I have a 6N2 Thunderbolt used with Yaesu FT-225/625 rigs but I have never tried it on AM.  It is as painful to move as its HF brother.

[The Slab Bacon]

Rodger,
          The Pacemaker and the T-bolt would really make a nice lash-up!! Thats a rig that you just dont see many of at festers.

I actually built a piss weak exciter for my T-bolt. A 2E26 (cause I have a bucketfull)
modded by a single ended 6V6------A WHOPPING 7w out!!    I figgered it was better to have a low powered exciter than to attenuate a higher powerd rig down by heating up a resistive attenuator. The drive requirements of a T-Bolt are so low in the AB2 mode that all you have to do is tickle it with a little RF to get full outpoot.
With many rigs used as exciters that was actually a problem, even if you used the "swamped input" mode.

[ke7trp]

Once its up and running, I will let you guys know how it works. Its no hurry for me. I have no room for the thing. Once I get my new shack built and I have room, I am going to lash it up to the valiant and Ranger and give it a shot.  One of these 4-400s in the GK500C does 350 carrier and 1200 PEP.  One them in the T3 does 550 carrier and 1800 pep.  The GK500 voltage WAS also low, but once I beefed up the primary wiring, Ran solid state rectifiers everywhere and doubled the Oil caps, The thing came up 500 volts. I dont see why the Tbolt wont do the same.  I realize its not Class C and not  nearly as efficient, but the thing is rated for 300 am.  The guys talking about 100 watts AM are just flat out wrong.

I talked to a guy 3 days ago with a Ranger and Tbolt in California. Off and on was a big difference on the air.  He said he runs his at 275 AM as it seems to sound the best and have enough headroom.  I honestly dont care what it does.  Its a novelty rig for me. Once In a while, I will fire up the ranger and Tbolt and say hello.  I have plenty of other big rigs here to put out a big signal.  But its just idiotic to come on here and say that this amp is only going to make 100 watts.. Jeesh..



C