Wednesday, March 18, 2015

MFJ-993b Antenna Tuner Power Switch Problem

  This another post from my Amateur Radio Blog that I thought I would share with my readers. It is a very common problem and this fix has helped mine. Here is a link to my Amateur Radio Blog http://hamradiokc2yti.blogspot.com/ .
  I own a MFJ 993B antenna tuner and have suffered from the dreaded on/off power switch failure. The antenna tuner functioned properly for about 4 to 6 months and then it would not power on. When the on/off switch was pressed it would have power and then shut off. I did some research on the internet and found that this was a common problem. I emailed MFJ and they sent me a couple of switches to replace the bad switch at no charge.
  Well I have replaced the switch at least four times and this would have been the fifth time. I started checking the internet for a better solution then to just keep replacing the switch. I found some switches at some suppliers on the internet such as Jameco and Digi-Key. I then came across a person that decided to replace the switch with a toggle switch.
  I checked my junk parts and found some on/off toggle switches that are 2amp 125vac, which will easily handle the current and voltage. My next step was to ohm out the six pin power switch to determine what the pin outs were doing. I found that 4 pins were either on or off depending on the switch position. I removed the defective switch from the smaller front board. I looked at the traces and found the two pins were shorted by a trace as well as the other two pins. The last two pins have no trace on either side of the board. I shined a light behind the board and found there are no traces at all going to those pins. They seem to be just for support.
  I should say it is a little tricky removing the small front board, because there is a grey ribbon cable connecting the small front board to the main board. Here is a link to a picture of the inside of the mfj-993b automatic antenna tuner https://www.google.com/search?q=mfj-993b+review&biw=1280&bih=610&source=lnms&tbm=isch&sa=X&ei=mx8KVcW8Koi6ggS6mYOACQ&ved=0CAgQ_AUoAw#q=mfj-993b+mainboard&tbm=isch&tbas=0&imgdii=_&imgrc=P4qgPDOVWy72DM%253A%3B01EX4NaZmiiJAM%3Bhttp%253A%252F%252Fimages.ges.cz%252Fimages%252Fpictures%252Fm%252Fmfj-993v.jpg%3Bhttp%253A%252F%252Fwww.ges.cz%252Fen%252Fmfj-993b-automatical-antenna-tuner-300w-1-8-30mhz-GES08901784.html%3B661%3B635 . Sorry it's a big link and I don't have any pictures of mine inside. I plan on getting for the post.  I soldered two wires to the two holes that have the traces shorted. I the drilled a hole in the lower right side of the front panel. I pretty much eyeballed it because the bottom case does slide in under it. I did put some electrical tape on the bottom under the switch just to make sure nothing shorts out. I then soldered the two wires to the toggle switch.
  I powered on the antenna tuner to see if it powered on properly. It powered on and off properly and the meter needles moved properly. I closed it up and connected back in place with my antenna switch and my ts2000 radio. I then tested it in the system and it is working properly. The best thing is if I ever have to replace the toggle switch it will be much easier to replace.
  Thanks for reading 73s from KC2YTI.     

Sunday, March 1, 2015

Icom, Yaesu, Kenwood...Which Transceiver Do You Prefer In Your Ham Shack









    YAESU HAM TRANSCEIVER












  There are some pretty awesome Ham Radios to choose from to have in your Ham Shack. If you have already had your Ham Shack going maybe it's time to move into a bigger Ham Radio. There are quite a few different Ham Radios in what I would call the middle price range it may be difficult to choose. My advise is to read as many reviews as you can before making any kind of a decision. The three major brands are Icom, Yaesu and Kenwood. There are other brands that are not doing to bad such as Alinco, which seems to be growing. The other choice is to go with a used Ham Radio through Ebay. I would make sure to check out the seller and read any reviews on the seller before purchasing. There is nothing wrong with buying used, but when spending that much money I would definitely protect your self and your investment. 

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This Blog is a place where you can access Amazon.com or Ebay in search of Ham Radio Equipment and Electronic Equipment. I may post about projects I am working on. I may post some videos, pictures or anything that Ham Radio Operators or any visitors may find interesting. I will also be sharing some of my posts from the other Blogs I run. It's a place where you can leave a comment on something you like or maybe a Ham Radio Project you may be working on. Basically it's a place where anyone can come and enjoy.
Thank You from Dan KC2YTI 73s