Best tube for a new, high power rig??

[VE3AJM]

Has there been a change in the 1500w PEP output power restriction in the US, and more importantly for some, how the FCC will measure 1500w PEP output from such a transmitter, because that's what counts? No more enforcement going on?

I only ask as I see references to an "AM Kilowatt" running 150% positive modulation, and 4x 813s running at 1600w input etc. etc... Dummy loads and "headroom" aside.

Al VE3AJM

[N2DTS]

I do not think anyone pays attention.
And what something can do and what its run at is different.
My 4x 4x150 rf deck can put out 1000 watts carrier but I would never run it at that, I would tear up all the electronics for blocks around most likely, and what's even worse, hose up the wife's TV show.

300 watts and under is what does it for me, but I bet some people run much more.
With OWL and a tuna, I would like to see anyone measure the pep power output of a station.

I think there are people running 10kw on cb, so I doubt the govt is going to track down someone running 1800 watts pep on the ham bands.

Then there is the antenna thing, you could run a kw out (4kw pep) into a crappy antenna and not be very strong on the bands.
You could also run 100 watts into a very good antenna and be strong, who is to know....

[flintstone mop]

Hi Al,
The U.S. hams were lead like cattle to the 375 watt carrier/1500P.E.P. thing. We thought the ARRL had our backs, but didn't.
Building a final amp using tubes with handles will quiet the aether very nicely.
Bad thing about that, is when you get to a real kilowatt output; you better have an antenna system that can deal with that type of power.
OK back to the thread about the best pube for a high power rig.

Fred

[Opcom]

I'm happy with the freedom to build or own whatever radio stuff I like. I enjoy the plus-size stuff and just like anyone else use a power meter and a scope to observe the PEP limit, in those cases where I have to approach it.

To build or modify a higher power piece of equipment so that it can play well at ham PEP levels is a nice accomplishment and it's fun. Fun is the main reason. Second is that it will last a long time, maybe never need a costly repair.

I don't feel tempted to exceed the limit. There might be some people who have poor self control where radio is concerned but I don't personally know of any or know what might lead their personality in that direction.

[flintstone mop]

I'm happy with the freedom to build or own whatever radio stuff I like. I enjoy the plus-size stuff and just like anyone else use a power meter and a scope to observe the PEP limit, in those cases where I have to approach it.

To build or modify a higher power piece of equipment so that it can play well at ham PEP levels is a nice accomplishment and it's fun. Fun is the main reason. Second is that it will last a long time, maybe never need a costly repair.

I don't feel tempted to exceed the limit. There might be some people who have poor self control where radio is concerned but I don't personally know of any or know what might lead their personality in that direction.

I think it makes good sense. For anyone to really hear any difference and move that stubborn S-meter even one increment takes 6dB. And that's a lot of power. Most ham stations antenna systems would not handle that increase in power without dangerous results. Shorting PL259's, antennas catching trees on fire, etc etc.
The secret is the antenna....long as you can get it and high. Some ham ops are stuck on city lots or in the 'burbs, and a 90 foot high dipole full length for 160 or 80 meters is going to be a challenge.
A quad of beautiful 813's modulated by a quad of 813's would certainly look nice and make a lot of heat for the Winter time in the shack.

Fred

[Steve - K4HX]

PL259s will easily handle 5 kW.

[W2PFY]

PL259s will easily handle 5 kW.

I have a 160 meter antenna fed with 250 feet on OWL that has a near perfect match around 50 ohms @  1.900. Great, no antenna tuner needed. I had a PL 259 pig tail going from a box outside to the OWL that I has hastily cobbled together so I could test the transmitter with this new no antenna tuner approach. So I go inside and fire up the big Westinghouse that can do 1 KW on fone and about 1.5 KW out on CW. Of course I had it  de tuned for the test  and proceeded to do a couple on atomic yeellllows and smelled something burning. Keeping with good amateur practices, and since the transmitter is on the other side of a wall, I keep it on transmit to witness the  origin of the smell! I looked up at the outboard RF ammeter and it was at full scale of 20 amps and the inside was as bright as a 100 watt bulb which is interesting since there is no bulb in it. Well I immediately hit the big red shut down button located on the rectifier cabinet and thought all is well. Funny, the burning plastic smell keep coming from somewhere so since nothing was on fire on the inside, I ran outside to discover that about five feet  OWL was burning making its way up to the cone of the roof. I lowered it and stamped it out! Long story short, the PL 259 can handle the power but the connection inside it need to be good

[K1JJ]

Nylon PL-259s are flame throwers.  Light brown phenolic are better.  

The best are the silver-plated, gold-tipped Teflon PL-259s and SO-239s.  They used to be common for a buck at flea markets due to some kind of military surplus, but are harder to find at cheap prices these days.

Bird wattmeters use Teflon SO-239s and we all know they can handle a lot of "Bird watts."  

BTW, watch out for moisture getting into a PL-259 / SO-239 connection when outdoors. The pin will become intermitent and produce a gooey blue paste.  The clue is when the receiver dies but comes back after some RF power is put thru the connector / antenna.

I find that coating the pin with some De-ox gray paste and then sealing the barrel connection well with wide 2" electrical tape - and adding a layer of clay works very FB in the WX.  RTV is OK, but the wind will peel it off after five years or so.

Actually, for 160- 40M, I always make direct coaxial connections to avoid connectors on outside antennas wherever possible. They are trouble waiting to happen.

T

[flintstone mop]

OK QIX , Steve
what tube have you decided on for your next transmitter???

And Al, VE3JAM
I always run legal limit, 375 watts. The RF power drift in my Kenmore TS850 creeps up and the amp is happily putting out 400 watts, oh my!!  I have a Bird peak reading meter, and making steady sounds with my voice into a dummy load, I have never seen it go to 1500 PEP.
Maybe a 1kc tone modulated 100% will show 1500 PEP. I think I even tried a 1kc tone and it didn't read 1500W......
It's just a bunch of theory of 4X the carrier, that the FECES will not be able to accurately measure, in a Ham radio environment.
Maybe a professional broadcast environment, but not Amateur radio.
Someone with a 5KW carrier would be noticed and easily caught and thrown in a dark dungeon with recordings of slop bucket noise and swishing carriers.

Fred