EMRFD Message Archive 2642
Message Date From Subject 2642 2009-01-26 10:11:01 bkopski ADVISORY: AD 8307 in Power Meter Applications
I've spent several weeks chasing issues related to use of the popular
AD8307 in power meter applications and the calibration thereof. The
new Folder "K3NHI_8307PM Calibration" contains considerable information
regarding newly uncovered issues with this part. The Folder includes
discussion, Excel formatted data, photos, and an updated Calibrator
schematic most of which are related to previously published QEX
articles. If you are using or considering using the 8307 in power
meter applications, this stuff is for you!
Cordially,
Bob, K3NHI2643 2009-01-26 13:38:55 joop_l Re: ADVISORY: AD 8307 in Power Meter Applications 2644 2009-01-26 21:09:50 Gary Johnson Re: ADVISORY: AD 8307 in Power Meter Applications
I can confirm that the 8306 is useful at lower frequencies. We used it in an FSK
demodulator with the carrier at 1 MHz, and there seemed to be no particular reason why it
can't be used much lower. Just use larger coupling caps. Same for the 8307, which worked
nicely in my audio-derived S meter (article in last Feb QST).
I last used the 8306 as a narrowband 10 MHz limiting amp in a scientific instrument, with
a Q=5 bandpass before and after. Excellent performance all around. That was based on
the AD eval board.
As for wideband noise in the 8306, all the AD X-Amp parts use the same basic cascaded
limiting amp. They all have the same issues. They are pretty quiet in and of themselves,
but it is up to the builder to make sure nothing undesirable leaks into the inputs. While I
have not tried to use the 8306 as a wideband RF power meter, in my experience with the
part it seems possible. Just be sure to lay out the board like the AD eval board with a good
ground plane and keep the output isolated from the input. No oscillati2645 2009-01-26 22:56:09 John Kolb Re: ADVISORY: AD 8307 in Power Meter Applications
a3-30 kHz sound level meter. Analog Devices has an ap note
on their site, "Operation of RF Detector Products at Low Frequency"
http://www.analog.com/static/imported-files/application_notes/896652515AN_691_0.pdf
John
At 09:09 PM 1/26/2009, you wrote:
>Joop,
>
>I can confirm that the 8306 is useful at lower
>frequencies. We used it in an FSK
>demodulator with the carrier at 1 MHz, and there
>seemed to be no particular reason why it
>can't be used much lower. Just use larger
>coupling caps. Same for the 8307, which worked
>nicely in my audio-derived S meter (article in last Feb QST).
>
>I last used the 8306 as a narrowband 10 MHz
>limiting amp in a scientific instrument, with
>a Q=5 bandpass before and after. Excellent
>performance all around. That was based on
>the AD eval board.
>
>As for wideband noise in the 8306, all the AD
>X-Amp parts use the same basic cascaded
>limiting amp. They all have the same issues.
>They are pretty quiet in and of themselves,
>but it is up to the builder to make sure nothing
>undesirable leaks into the inputs. While I
>have not tried to use the 8306 as a wideband RF
>power meter, in my experience with the
>part it seems possible. Just be sure to lay out
>the board like the AD eval board with a good
>ground plane and keep the output isolated from
>the input. No oscillati2647 2009-01-27 03:31:08 joop_l Re: ADVISORY: AD 8307 in Power Meter Applications 2662 2009-01-30 10:49:50 joop_l Re: ADVISORY: AD 8307 in Power Meter Applications
http://www.analog.com/static/imported-files/application_notes/896652515AN_691_0.pdf
that describes the use and behaviour of the AD8306/7/9 and others at
low frequencies. They answer most of my questions.
Cheers,
Joop - pe1cqp