I forgot to include that with just a 4 foot cable on the output of the tuner
between tuner and 75 ohm load the SWR was 1.8:1.
With the 10 foot cable SWR was 1.46:1.
With the 10 foot and 4 foot cable the SWR was 1.4:1
73
Gary K4FMX
> -----Original Message-----
> From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Gary
> Schafer
> Sent: Monday, January 12, 2015 9:06 PM
> To: 'amps@contesting.com'
> Subject: [Amps] Input SWR revisited
>
> This afternoon I warmed up the HP vector network analyzer and tried a
> few
> things.
> First I calibrated analyzer port to 50 ohms.
>
> Then I put a 75 ohm load on it and it read 1.5:1 SWR as would be
> expected.
>
> Next I added a 4 foot and a 10 foot 50 ohm cable between the analyzer
> and
> the 75 ohm load. The analyzer still showed an SWR of 1.5:1 as expected.
>
> Then I hooked up a small Kenwood manual tuner to the analyzer with a 19
> inch
> cable and placed the 75 ohm load directly at the output of the tuner.
> Adjusted the tuner for as near to 1:1 SWR on the analyzer (1.08:1).
> Then added the 4 foot cable between the tuner and the analyzer. Then
> added
> the 10 foot cable between the tuner and analyzer.
> The SWR remained at 1.08:1 no change in SWR! I did not touch the tuner
> tuning.
>
> Then reconnected the tuner to the analyzer with the 19 inch cable and
> placed
> the 10 foot cable between the OUTPUT of the tuner and the 75 ohm load.
> Without re-adjusting the tuner the SWR read 1.43:1
>
> Then added the 4 foot cable to the 10 foot one and the SWR was 1.40:1,
> almost the same.
>
> I ran this around 30 MHz and then around 26 MHz to move away from a near
> 1/2
> wave length but the results were the same.
>
> The same connectors, cables and adaptors were used with the cables in
> front
> of the tuner as they were in back of the tuner.
>
> Looking at another screen on the network analyzer I could see the
> resonance
> of the tuner shifted in frequency when adding the cable on the output
> side.
>
>
> 73
> Gary K4FMX
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|