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LF: Re: RE: LPF coils and VY1JA to 1W ERP

To: <[email protected]>
Subject: LF: Re: RE: LPF coils and VY1JA to 1W ERP
From: "J. Allen" <[email protected]>
Date: Mon, 13 Nov 2006 13:41:11 -0000
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Hi Andy,

Slight Saturation in the core causing a loss in inductance at high power
perhaps?

No, the tests were performed with the same transmitter at the same tap and power output through the same coax to the same dummy load.

Also, switching transmitters from the transmitter lent me by Steve, VE7SL, to the prototype IR640 amp made no difference in the readings, even at approximately double the power.

Assuming the air wound and cored inductors were adjusted to exactly the same
values initially.

Yes, they were wound to the same values... as close as possible to 54 uH.

Direct coupling in the near field from your original air wound coils
influencing the coupling into the scope of your V and I pickoff, that is not
present in the closed torroidal cores.

The pickup torroidal cores were enclosed in a metal box in both cases and the LPF with the air would coils was about 0.5 meters distant.

Can you wind the power down and measure the phase difference which would
show up 1) but not 2)?

The difference is apparent with both with the 80 Watt transmitter and the 155 Watt transmitter and the dummy load. I also notice a slight shift added to the traces from the antenna, which is why I was asking if I now tune so that the transmitter sees a perfect trace because of the shift added by the LPF or if (only a perfectionist would tune for this slight of a lag) I tune to match the slight current lag, knowing that the indication seen with dummy load represents a purely resistive load.

The basic question is this. Is my instrumentation now in error or is the system under measurement in error?

J.






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