Its that time of year again....

[N2DTS]

Why is it the older I get, the less time I seem to have?
Anyway, its turning into radio season around here, and while I did not get much done last year, maybe this year  will be better.
I did have a few projects last year, I think I did the vfo/exciter, and re-did my 4x150 rf deck, but never did anything with my 40 meter micro rig.
Maybe I will get somewhere on that this year.

I did get on 40 meters a few weeks ago, with the pair of 4x150's modulated by a pair of 4x150's (same as 4cx250b tubes) and that combo seemed to work really well.
Separate power supplies for rf deck and modulator equals lots of peak power output.
The RF deck is limited by the plate tuning cap voltage, so I was running it at 1200 volts and 300 ma for 300 watts out, the tubes run at 100F with just a muffin fan, and peak power hits 1500 or more watts.
They are allowed to go up to 480F!

I found a higher voltage cap at rf parts and ordered it, from 2000 volts to 4000 I think, and I have a 500 pf 5000 volt door knob in series with it.
I should be able to get the voltage up to 1500 for some 'head room'.

New in the can 4x150/7034's can be got for $25.00 which is a deal for a 250 watt tube.
They make 600 watts of audio in AB1, and seem to work real well in class c plate modulated service.
I ebay'd another one, you can never have enough spares of tubes you actually use...

[Opcom]

Yay! radio season! The cooler weather attracts me to the shack as well. Good on the 4X150's as good as a 250 in most places!

[Steve - K4HX]

Ya gotta like a tube that comes in a can.

[N2DTS]

Yes, they stay nice and fresh!

Ya gotta like a tube that comes in a can.

[N2DTS]

I got my new cap today and put it in the 4x150 rf deck, and took out the series 1000 pf 5000 volt door knob.
Ran it up to 1500 volts at 300 ma and got 400 watts out, 109F anode temps.
I took it up to 500 watts for a while as a test.
I put plenty of audio on the carrier and nothing zorched, a good sign.
So I can run it at higher voltages and less current if I want, or the other way around.

[w1vtp]

I got my new cap today and put it in the 4x150 rf deck, and took out the series 1000 pf 5000 volt door knob.
Ran it up to 1500 volts at 300 ma and got 400 watts out, 109F anode temps.
I took it up to 500 watts for a while as a test.
I put plenty of audio on the carrier and nothing zorched, a good sign.
So I can run it at higher voltages and less current if I want, or the other way around.

Pictures? 

Al

[N2DTS]

Here is a picture when it was being rebuilt:
http://n2dts.smugmug.com/Ham-radio/i-QJBq4hR

That cap is a 2000 volt job.
I did some more tests today, plugging in my ebay tubes one at a time and testing the plate current and power output, and then marking them.
I then put the 2 best ones in and ran the power up and arced the new cap, melted one plate down to slag.
They sure don't make caps like they used to!

I need a still higher volt cap if I want to run the voltage up higher.
I have a bunch of good new 4x150's though.