PG XL amplifier and Spiderbeam antenna

Mr Radio

I am keen to know if someone is using PG with a commercially made Spiderbeam antenna. My concern would be about original balun power handling capacity and size of antenna wires. I would appreciate any comments and observations about a such setup.

Tom

Mark_WS7M

Hi Tom,

I have a spider beam but its in a box and I couldn't tell you the ratings.

With the PGXL you can control your output power to what you wish. I often run CW at 750 or 1kw instead of the full legal limit. It is just the RF power slider that it is. Or you can use some tools to auto set it.

But here is an important point: All baluns regardless of their "power rating" will heat with use. The more they heat the less effective they are. If you have a high SWR your balun heats quicker.

When I put up my first 80m loop I had a 5kw rated balun in place from Balun Designs. But I had not tuned the loop for 40m and the SWR was around 2.5:1. I used my HF Auto tuner to tune it to 1:1 which it did then I tried to operate some FT8.

Well that didn't work real well. As I sat there watching it transmit the SWR was slowly climbing and the tuner kept trying to fix it and eventually it faulted. I let it cool down and the tuner had to retune only to get a repeat performance again.

So I think if your spider beam is well tuned you should not have an issue running at the limit of the balun or perhaps slightly below.

I don't know the wire size but I think anything 14ga or better should handle it just fine. I used to run 1.5kw into 14g wire in my 80m loop with no issues for several years.

Maybe a current spider beam owner will hope on here.

Mark - WS7M

halmassey

Here are the "fusing currents" for various American copper wire gauges. The chart shows you when the wire will open up. Fifteen hundred Watts into 50 Ohms produces I squared times R amount of power. You can rearrange and substitute to get I. Your antenna feed point will be something other than 50 Ohms depending on the antenna but this will give you the basic tools you need to work on the wire question. For 50 Ohms and fifteen hundred Watts there are 5.5 Amps. It takes a fair amount of current to open up even 30 gauge copper wire as you can see. https://www.powerstream.com/wire-fusing-currents.htm