Home |
Search |
Today's Posts |
#7
|
|||
|
|||
Using Tuner to Determine Line Input Impedance
On Jun 3, 4:19*pm, Owen Duffy wrote:
Tom Rauch (one of the designers of the '259B) posted this info re interference: "BC interference causes the bridge in the analyzer to remian (sic) unbalanced even with very low SWR, so the analyzer will read a fixed minimum SWR when BC interference. It will read that way on any frequency from dc to daylight. For example if the unit falls asleep the SWR meter won't drop to zero. That's an indicator of BC interference or external voltages being applied to the measurement port." Owen Many thanks Owen. I just confirmed I have a BC interference issue. When I placed a 100 ohm resistor across the 259B antenna terminal, the unit correctly read 2.0 (well actually 1.9) swr, 100 ohms R and 0 X. When it entered "battery save" the analog swr and impedance meters both dropped to zero. The digital display stayed the same. When I hooked my antenna up the analog swr meter only fell to 1.4 when the unit entered "battery save" mode. The impedance meter did drop to zero. When I installed a 4:1 balun at the antenna feedpoint the swr fell to 1.2, but still not zero when the analyzer entered sleep mode. Apparently the BC signal is at least to some degree differential in nature on my feedline. Anticipating all this, I wrote MFJ about the usefullness of their their tunable analyzer filter to combat a strong FM broadcast signal. They replyed that it would work. I wonder how well. The tunable filter costs around $100.00. |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
LS-3 speaker input impedance | Boatanchors | |||
Antenna Input Impedance | Antenna | |||
[OT] Rcvr antenna input impedance | Antenna | |||
NEW PROGRAM - Input Impedance & SWR of Resonant Antenna. | Antenna | |||
Sony input impedance | Shortwave |