Search results

Real world stuff that works. Cptn kw is right about having to make the driven element shorter than one used with a gamma match. A properly executed gamma match will not ruin the 90 degree null. I have a 5 element vertical here that used to get alomst 40 dB rejection off the sides with a...

Auto repair people are desensitized to know-it-alls. They deal with them daily. Time will tell weather you are really the dumb one. In the meantime you could do a parasitic draw test on your vehicle. Disable the underhood lamp, shut everything off. Remove the negative battery lead...

You get much more accurate and repeatable data from licking your finger and holding it against the wind.

Consider a GU-74. The circuit can be changed over to cathode drive for much cleaner output too. 4CX800A = GU-74B = gu74b = gu74 NEW! CHEAP! LOOK! - eBay (item 180396140688 end time Dec-09-09 14:13:21 PST)

A good mobile antenna might not ever exhibit a 50 ohm impedance. It depends on the installation loaction and a bunch of other factors. If you match it with a specific length of 75 ohm cable and read an accurate low VSWR at the radio everything is OK. You cannot fool an SWR meter. Your cable is...

There's nothing wrong with using 75 ohm cable as an impedance transformer to match the impedance of your antenna to the rig. I'd just make sure the guy has it figured out correctly. If he does he's no dummy. IIRC some Wilson antennas come with a length of 75 ohm cable for just this purpose.

The only real problem with sweep tubes is people pound the hell out of them.

4 sweep tubes might put out 350 watts but on AM there won't be any dynamic headroom left over for your audio. People will tell you it sounds crunchy and the modulation sounds low. 100-125 watts carrier would be a little more what those tubes could do with a lot of air on them and the...

If you want R = 50 and X = 0 in a mobile installation where the counterpoise is sheet metal you will need to experiment a little. Try a small amount of capacitance in parallel with the feedpoint. On 27 mega-hurts maybe 10 to 35 pf would be a starting guess. A small air variable can be used...

It's true that smaller core sizes work at higher frequency. This amp would not however work too well in a mobile installation directly hooked to the alternator stator. The voltages would be all over the place without some way to vary alternator field current. I don't think those toroids will...

I heard some east/west stuff going on but didn't work any.

What's wrong with Captain Megawatt?

Thanks for taking the time to post this.

Harris RF350K AM-7224.

This is all well and good except for the broad brush. There are idiot contesters and OK contesters. The idiots give the whole game a bad look but it's important to distinguish the difference. A lot of great ham radio gear and procedure was developed by and for contesters.

Have you tried changing the GP angle by moving in on the support to wire connection? The earth is going to change things that close.

That's why you bulldoze the driver section. It isn't needed. The power supply is pretty good. Some driver tube sockets can be reused for more tOObs in parallel with the output stage.

This is a tube amp. It doesn't need a bandpass filter. The Pi-net is bandpass. Same for almost every hambone tube linear commercially sold.

I have one of these that looked like it had been dragged by a horse across town. I bulldozed the driver section and made it into a 6 holer 6LQ6 monobander. It works pretty well.

Just a coupla thoughts: The broadcast rig has a constant load on the supply in the R.F. amp. The modulator is the dynamic load. Properly sized power supply components can be somewhat smaller with the constant load. If you use the amp on single slimeband the situation will be quite different...