[600MRG] Something failed the TX or Amp used in my experiment

[John Langridge]

Last nights problem has returned and it was not power supply related as originally thought.

Shortly after 0045z tonight, I noticed the signal got very weak while monitoring.  I visited the antenna site and found that the antenna match was now 0 ohms!  The amp was happy dumping power into the ground, however, which is encouraging given what I have planned next.  A sweep of the antenna showed no dip at all from 1700 to 100 kHz.

SO this might look like a failure in this phase of my experiment but if the antenna is mechanically sound (verifying that now), meaning that thermal changes in the antenna structure are having a minimal impact to the function of the antenna where it is intended to be operated, it seems to suggest that the environment and/or ground has changed pretty significantly, which we all know that it typically does and is most often seen when poor a poor radial system is presented.  That said, I did NOT see this type of shift last week using the 20m inverted vee as a marconi over a poor radial system.  Temperatures and wx have changed very little.   The match during the first trial was rock solid all night.  

Something else to consider on the next phase of my wild ride to insanity...

I'm running straight U3 tonight from the "real" antenna at home tonight, around 10 mW ERP...


73,

John XIQ



________________________________
 From: John Langridge <jlangridge at sbcglobal.net>
To: "600mrg at w7ekb.com" <600mrg at w7ekb.com> 
Sent: Sunday, January 19, 2014 3:25 PM
Subject: Re: [600MRG] Something failed the TX or Amp used in my experiment
 

The problem from last night has been resolved, we think.  Looks like a PS went south and as it did it dragged the U3 drive down with it.  Everything else was tip-top..

SO running right now and hopefully through around mid-afternoon tomorrow will be a GAP Challenger vertical, with 4 radials, 3 @ 25 feet and 1 @ 50 feet.  The base has been insulated and resonance is achieved with a coil...

Results last night were surprising and excellent.  Its a shame that it was not able to run the whole night.  Hopefully tonight will make up for that.

Thanks again for listening and all WSPR reports are appreciated. 474.2 dial freq...


73,

John XIQ



________________________________
From: John Langridge <jlangridge at sbcglobal.net>
To: "600mrg at w7ekb.com" <600mrg at w7ekb.com> 
Sent: Saturday, January 18, 2014 8:15 PM
Subject: [600MRG] Something failed the TX or Amp used in my experiment


There has been a failure on the U3/amp combination I am using.  I will have to investigate further tomorrow and resolve the problem.  Nothing catastrophic, the signal just went intermittent and then went away.


Sorry about that but thanks for the reports so far.  They have been quite interesting and not that bad considering the antenna, a GAP Challenger fed at the base with a coil, radials lifted and insulator at the base.  Its not really practical in most senses but it was fun to make it work until it didn't.  The reports reflect that it did radiate with 4 radials.  I have a lot of info to work through and may continue to run it once I get the problem resolved tomorrow.  My guess is that the match got ugly and the FET died.


On another note, I suspect my next test will be of a very large earth electrode system.  XKA and I have been talking about it for over a year now and I now have access to a few acres that could be worthwhile if I can get the antenna matched properly.  details to follow.


I am going to transition to WSPR at my primary operating position in a few moments.

73!

John XIQ
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