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Re: LF: Re: PA3BCA

To: [email protected]
Subject: Re: LF: Re: PA3BCA
From: Stefan Schäfer <[email protected]>
Date: Sat, 13 Aug 2011 00:17:28 +0200
In-reply-to: <4FB899125601413A9077646E2728C784@PcMinto>
References: <[email protected]> <52970A62D1224CAF9A966D1743DCBF00@PcMinto> <[email protected]> <4FB899125601413A9077646E2728C784@PcMinto>
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Hi Minto.

The signal must have been about 6 dB lower than yesterday. Still have to go back to the old system, unfortunately. Difficult to do good measurements here in the "shack" where all the stuff is floating either on mains voltage or on 137 kHz or a mixture of that. Have a battery supplied oscilloscope but anyway.

I didn't got more than that what you saw, no higher power was possible even when running the SMPS at 320 VDC. Unfortunately now i saw what the reason was/is: Some of the turns of the loading coil moved a bit and so i was outside the resonance. Since  the Q of the TX antenna is very high, the power goes down quickly when beeing outside the resonance. I haven't had the tuning-meter (U,I, phase) in line, and just tuned the shack-internal variometer for a maximum signal.
After the unwanted fault and replacing the FET i had to find other problems like a non conducting shunt resistor (current sensing). This wasn't visible. For some reason the current limiting didn't work then. A second loud BAAAAAAANG caused me to let it be for this week! Now two mains fuses here at QRL are OFF and i don't have the key to put them in again.
Anyway, i'm in holiday for the next 2 weeks and they will be back in when i am back and no one will remember that, hopefully, hi.

Actually all that stuff should be exchanges in a QSO :-) BTW how about YOUR PA? :-)

73, Stefan/DK7FC

Now trying to bring the coil back to its previous L...


Am 12.08.2011 23:07, schrieb Minto Witteveen:
Hi Stefan.
 
I see your CQ on my grabber at this moment.
How does your ERP now compare with yesterday (during your QSO with Mal)?
It looks like S/N is now worse here then yesterday. Reason might be the loop versus the miniwhip (with the miniwhip the winner). But on the other hand there seems to be a lot of QRN (because of lightning at this moment.
 
73’s Minto pa3bca
 
 
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Ceterum censeo Carthaginem delendam esse
 
Sent: Friday, August 12, 2011 20:02
Subject: Re: LF: PA3BCA
 
Hi Minto,

Am 12.08.2011 19:42, schrieb Minto Witteveen:

How much power were you generating?

73’s, Minto pa3bca
 
 

It changes all the time. Not even sure since i just have an E field probe to decouple some power from my TX antenna and feed it to a 50 uA amperemeter, shunted by a potentiometer. This poti was adjusted to show 100% full scale when using 120 W RF before some weeks. Now reduced the parallel R on the poti so it shows just 25 uA then. Got 50 uA anyway by QRO and more (not sure). So it should be arround 500W. This is -6 dBfs :-)

But the antenna, i.e. the coil and its cover is very lossy it seems. When there was rain, i have up to twice the losses :-( Need to search for an alternative cover (mustn't burn, so a water barrel is no alternative...).


73, Stefan/DK7FC
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