[TowerTalk] VSWR Heating in Chokes and Baluns

[HP]

Got sent by accident -- I would not try this except with a rugged tube amp and watch it carefully feeding the series resonated case- 
The core may heat very rapidly . I had decided to not send it . 

I did basically the magnetizing flux portion years ago evaluating Q1 , Q2 Q3 Indiana General rods for a 1.5 KW 
antenna loading coil application in the 1.5 to 3. 4 mhz region. Along with heating we were looking at whether 
there were any IMD issues at high levels of amp turns -We did not see any even at levels that heated the cores so fast 
it was a moot point . I also learned to not cool the cores too fast or I had a lump of useles grey 

Hank K7HP 

----- On Sep 6, 2020, at 11:48 PM, pfizenmayer <pfizenmayer at q.com> wrote: 

| Ok -- here is a suggestion ----- if the question is what is causing the cores to
| heat ....

| some "electric field" or ampere turns magnetizng flux.

| Make a short piece of bifilar transmission line - parallel or twisted but with
| insulation that will withstand heat -like teflon.

| Make the line it long enough to put some 5 to 10 turns on a subject core. Set up
| your tx to fed a dummy load with this
| section of line/core in series and run say a Kw or so into the dummy load -
| calculate the current . For this case
| there should be nil amount of ampere turns magnetizng the core. Measure the core
| temperature after x min or seconds

| Now just disconnect the "ground " side side of the bifilar transmission line at
| both ends -leave it float and insert a capacitor
| of the values needed in series with the "hot' conductor to series resonate out
| the inductance of that winding and run the same
| power -. See what the temp is after the same X seconds or min .

| ----- On Sep 4, 2020, at 5:04 AM, W4TV Joe Subich <lists at subich.com> wrote:

| Balun/common mode choke what is the difference? Neither
| should be magnetizing the core unless you are talking
| about a magnetically coupled transformer like the isolation
| transformer in an FCP system.

| 73,

| ... Joe, W4TV

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