Re: QDX with Elecraft T1


Paul Christensen
 

"I do not understand. Almost 3dB loss? Calculated at 70cms? 73 Alan G4ZFQ"
70 cm? In the example Wolfgang provided, a load impedance of 227+j521 = 29:1 SWR (50) on 20m. Add in 3m of RG-58 coaxial cable between the T network and load, and we have loss on 20m in addition to the T network loss that is mostly due to inductor heating. See the attached TLD screen capture.

TLD does not show tuner loss, only the 3m line reflection mismatch + dielectric loss of 1.55 dB. T network loss as computed in TLW is approximately 0.8 dB -- that assumes a coil Q guess of 200. I've no idea as to the T1's actual coil Q but it makes a big difference when computing tuner loss. I would be surprised if the T1 switched-inductor Q was any better than 200. More than anything, the example shows why a combination of high SWR and line loss do not mix well together.

Paul, W9AC

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