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Topic Created Posts Views Last Activity
NANOVNA SWR readings Nov 10th 2019, 17:19 2 1,116 on 12/11/19
Kenwood TW-4000A overheater? Aug 27th 2019, 20:46 3 832 on 28/8/19
power for Kenwood TW-4000A Aug 22nd 2019, 18:14 5 779 on 25/8/19

Latest Posts

Topic Author Posted On
NANOVNA SWR readings KN6CWJ on 10/11/19
I received my technicians license about a year ago and I'm studying for the general I currently have a Boefang HD UV 82HP(rookie mistake) an old kenwood-TW-4000 that someone gave me. But you should see my Christmas list. One area that have drawing my attention are types antennas and performance. I have read a lot of articles and bought a NanoVNA to measure the SWR on the HD antenna that I have. The scan provided me with some output, but I am not sure exactly how to interpret the findings. The forum doesn't provide a method to upload a file so I'll do my best to describe it. The S11 graph: Y axis (.09,1), X axis (140.0m,160m). The plot line was (.58,.26,.38). The S11 VSWR Y axis (1.0,4), the X axis was the same. Its plot was (3.73,1.60,2.39). The S11 return loss(db) graph Y axis (0,20) X axis the same. The loss plot, was (4.9,11,7.5). How do I go about interpreting the findings? I have already started to build a simple ground plane antenna but a need a reference point to understand the NanoVNA graphs as I try and tune it.
I hope this make sense to someone. Being so new that this it can get a bit frustration as I learn to walk in this new realm
Kenwood TW-4000A overheater? KN6CWJ on 28/8/19
Another success story. Thank you W1VT for pointing me in the right direction.
Kenwood TW-4000A overheater? KN6CWJ on 27/8/19
This is a continuation of my immersion in to ham radio and working with a very old Kenwood TW-4000a. With the assistance of member of the forum community I was able to power up the Kenwood and there were signs that it was working. Next with the assistance of others I built a 2-meter J-pole out of some copper left over from a bathroom remodel. Did not have any coax with the right connector so I disassemble an old CB radio antenna and connected it to the J pole. Much to my surprise when I fired it up and changing the antenna, I could receive transmissions from a repeater located about 40 miles away. I had setup the radio and antenna on our deck which turned out to be a bad idea. The temperature that afternoon around 95+ degree. Something must have fried. The Kenwood still had power but it no longer scanned and I could not manual change frequencies. I would get a repeating beep. I thought that if I disconnect everything and allow it to cool down it would reset itself. Unfortunately, it did not have any effect. I did a YouTube search that provide directions to disassemble the Kenwood and how to change the 3v battery. I have not put the Kenwood back together yet but I doubt that the battery could be the problem. I have been able to download the schematic. So, my question is if this is an overheating problem where would I begin to look. Using the schematic as a guide where should I begin my problem determination.
power for Kenwood TW-4000A KN6CWJ on 25/8/19
Got It. Thanks
power for Kenwood TW-4000A KN6CWJ on 23/8/19
Thanks for the explanation. As I mentioned this is all new to me. Taking what you said I connected the AC adapter (12v 2A) directly to the radio. With the multimeter it was 12 volts and .4 amps. But as you explain when I press the ptt the amp jumped up to 2.3 amp. So, one can now conclude it takes more current to send than receive. A day of enlightenment! This of course brings up the next question. How can you increase amps without increasing voltage? Does ohm law get in the way?

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