Anyone using the 10Mhz external reference ?

[Brad Jeffries]

Experimenting with the 10Mhz external reference driven by a GPSDO that I previously bench marked to a lab reference.   If I use the external reference a VHF GPS beacon (using transverter clocked by HL2) seems about 22Hz in error.  If I use the internal reference the frequency is spot on.   If I observe the 10mhz tone out of the GPSDO using the internal clock it shows up spot on 10Mhz. 

Going to look at the PLL chip modulus size but was curious if anyone else has looked at this feature.  

Love the HL2 especially with the transverter I picked up at ham fest for $20 :)

73

Brad

KN4ODM

[Brad Jeffries]

https://github.com/softerhardware/Hermes-Lite2/wiki/External-Clocks

I need to RTFM :) I will use Quisk and WWV to measure the deviation less the transverter.   

[Mike Lewis]

Note that Thetis for HL2 has CL1 and CL2 configuration menus also builtin.

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From: herme...@googlegroups.com <herme...@googlegroups.com> on behalf of Brad Jeffries <kn4...@gmail.com>
Sent: Monday, May 8, 2023 12:07:45 AM
To: Hermes-Lite <herme...@googlegroups.com>
Subject: Re: Anyone using the 10Mhz external reference ?

 

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[Daniel Estévez]

On 08/05/2023 02:44, Brad Jeffries wrote:
> Going to look at the PLL chip modulus size but was curious if anyone
> else has looked at this feature.

Hi Brad,

Here are some experiments I did with a 10MHz reference:

https://destevez.net/2021/11/hermes-lite-2-external-10-mhz-reference/

This was with an HL2 beta2, but I think most is applicable to later models.

Best,
Daniel

[Brad Jeffries]

Thanks Daniel!   Looks like my  error is in the 116Mhz clock I am using for the VHF transporter  LO.  I went back to HF and when using the GPSDO WWV shows no error in the calibration.  If I use the HL2 crystal I get a small error as expected.   I will look into the 116Mhz clock a little more.   The amazing thing is how good normal comodity compensated crystal oscillators are these days. 

73 

Brad