[R-390] UnBal for R-390A

[2002tii]

Roger wrote:

>If you have some matching device out front of the receiver then we 
>want it in place and we want to couple the signal generator through 
>it to the receiver.
>
>Use what ever signal level you need, Just hang the signal generator 
>to the antenna with a small 1,000 - 100 pf CAP. Then trim up the RF 
>input transformers to get the most signal into the receiver.
>
>This will at least get you the best match between the antenna you 
>have and your receiver through the coupling circuit you are using.

If you want the antenna to control the feed impedance (and you do if 
you are trying to match to it), you probably want to use a capacitor 
a good deal smaller than 100 pF to couple the signal generator.  Its 
reactance should be an order of magnitude higher than the antenna 
impedance at the feed point.  One would typically use 2-5 pF, even 
less above 10 MHz.  Alternatively, a 50 k ohm resistor works pretty 
well, as long as its parallel capacitance is less than 1 pF or so.

Best regards,

Don

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