Re: Very Late Start - Type 2


K5ESS
 

I would offer a word of caution on the AD9851 modules. The Type I modules
(three rows of seven pins) have been very popular in VFO and antenna
analyzer projects. This has resulted in a doubling or greater in price for
these modules. Type I modules from some suppliers have chips that are marked
as a 9851 such but in fact are 9850 chips. These modules need a clock
setting of 120 MHz with the clock multiplier bit enabled in order to output
the correct frequency. The '9850 chips do have an undocumented X4 clock
multiplier. I have not heard of any reports of Type II modules that have
this defect.
Mike
K5ESS

-----Original Message-----
From: PHSNA@groups.io [mailto:PHSNA@groups.io] On Behalf Of Clifford Heath
Sent: Tuesday, September 25, 2018 11:12 PM
To: PHSNA@groups.io
Subject: Re: [PHSNA] Very Late Start - Type 2

On 26 Sep 2018, at 1:20 pm, K5ESS <k5ess.nothdurft@...> wrote:
The PHSNA needs a fairly pure signal source to give accurate results,
generally meaning the signal source should be a sine wave which the
AD9851/51 can provide. The SI-5351 has a square wave output which is rich
in harmonics so it's not a good choice for the PHSNA.

Good call. The PHSNA has no front-end or band-pass filtering,
so it's susceptible to any interfering signals, including its own
harmonics. Especially given that your DUT is likely to react to
harmonics more than to random interferers, this is a big worry.

AD9850 modules in the Type II (two rows of 10 pins) can still be had on
Ebay for a reasonable price ($14 + $2 shipping item 472030418663) . The
AD9851 modules are about twice the price.

The AD9851 are good to 50MHz, usable to 70MHz,
which is more than twice the AD9850. Recommend!

Clifford Heath, VK3CLF.

Mike
K5ESS

-----Original Message-----
From: PHSNA@groups.io [mailto:PHSNA@groups.io] On Behalf Of Curt via
Groups.Io
Sent: Tuesday, September 25, 2018 9:21 PM
To: PHSNA@groups.io
Subject: Re: [PHSNA] Very Late Start - Type 2

Will

Thanks for reply.

Okay I think I see Uno R3 for less than $8 from a us supplier. So now I
just need to id which source for a type 2 9850. Not sure I am ready to mod
and code for the si5351.

Curious what soldering you might need done to get yours assembled? I will
be checking my stash for board components as I may have some extras there.

Curt







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