Oh, I guess I should have thrown in a couple of generally-applicable
guidelines that should go without saying when using ANY sweep gear like
this:
- terminate the unused port on the duplexer with a high-quality 50 ohm load
- it's a good idea to use 6 dB or greater pads on inputs and outputs of the
test equipment
- use high-quality test cables (double-shielded when you're measuring
isolation)
- avoid using adapters
etc. etc. etc.
--- Jeff WN3A
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Jeff DePolo
> Sent: Friday, August 06, 2010 4:21 PM
> To: [email protected]
> Subject: RE: [Repeater-Builder] Measuring duplexer insertion loss
>
>
>
> > Can somebody please explain how the insertion loss of a duplexer is
> properly measured using a HP 8920A (with specan).
>
> 1. Connect duplexer Tx port to duplex port on 8920.
>
> 2. Connect antenna port on duplexer to antenna port on 8920.
>
> 3. Go to spectrum analyzer screen.
>
> 4. Set center frequency = repeater tx frequency
>
> 5. Set generate mode to TRACKing
>
> 6. Set input to ANTENNA
>
> 7. Set generate port to DUPLEX
>
> 8. Set generate level to 0 dBm
>
> 9. Set the sweep span to something reasonable, like 500 kHz.
>
> 10. By default, the marker should be at the center graticule,
> which should
> be the Tx frequency you entered in #4 above (if not, go into
> the marker
> menu, and set the marker to 5.00, which is the center of the
> display). The
> difference between the marker level and the generated level
> is the loss,
> minus your cable losses.
>
> For example, if you're generating 0 dBm, and the amplitude at
> the marker is
> -2.10 dBm, and you have 0.5 dB of patch cable loss, the insertion loss
> through that leg of the duplexer is 1.6 dB.
>
> Repeat the same test for the Rx leg of the duplexer by moving
> the cable from
> the Tx port to the Rx port, and changing the center frequency
> to the Rx
> frequency.
>
> > P.S.: Is it correct that a duplexer that has 40 dB isolation
> > in each leg does have 80 dB overall isolation?
>
> No.
>
> --- Jeff WN3A
>
>
>
>
>
