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Yaesu 101b burning smell on 40 meters

AE5RD

AE5RD

Reformed CB'er
May 4, 2005
136
1
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I kept smelling a burning smell everytime i keyed up on 40 meters. I took the cover off and looked inside the rig while i keyed and i saw some arcing on the choke. Where can i get another choke and what could have caused this? It took a while to get my wire tuned to 40 meters but the swr is 1.4 to 1 now.
 

I don't have any info on the 101 parts on hand, but it sounds from your comments that you might have been running the antenna WAY out of resonance. I gather that from your comment "it took awhile to get my wire tuned to 40 Meters, but the swr is 1.4 to 1 now". I am assuming, too, that this is an RF choke in the PA, right? If so, a mis-matched antenna could create heat. I am not all that familiar with the 101 (haven't messed with one in 15 years), but you would want to be cautious about excessively high SWR. In addition to chokes, you can flatten tubes, pop drivers and PA transistors, even burn out your filaments. One point four is GREAT and tube rigs will tolerate much more, but when SWR gets beyond
2.1, I start to get nervous & get to looking for the cause! :D

Anyhoo, at first glance I suspect you may have been simply runnning the rig a bit "hot" due to SWR. That choke should be easy to find, or you might wind one depending on the style.

73

CWM
 
You shouldn't have to worry too much about the antenna SWR with a hybrid rig like the FT-101 series. If the pi-network output circuit is adjusted properly, it will isolate the finals (pair of 6146s, IIRC) from the antenna.

Now then, if that circuit is NOT adjusted correctly, there are a whole bunch of things that can go blooey, and RF chokes are in that bunch.
 
burning

Here is an update. I went ahead and swapped rf chokes from my other 101ee and the rig works great, I found an high power transmitter choke in the rf parts catalog. It is 1.8 - 30mhz ceramic choke. I was wondering if i could use it in my 101? It costs about 25.00. I think I will try it. Just wanted to see if i get any feedback.
 

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