[hpsdr] external 10MHz reference input

[Tokio Endo]

Hi Bert,

I had the same problem with an external clock 10MHz a couple of months ago.
With the help of Phil, VK6APH, I changed the value of the famous R141 to 50 ohm. It cleared the problem for my case. Please make sure that the internal clock is stopped by the jumper and look at the the clock wave just after the wave conversion circuit by oscilloscope. I hope it will help you.

Tokio
JA1CCA

2013/05/18 16:58、"H.A.Meijer" <meijer.ha at home.nl> のメッセージ:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi,
> 
> Well this 30-40Hz jumping is with the on-board 10MHz TCXO, someone mentioned that this is coursed by
> the internal temp compensation.
> For me this is unacceptable, maybe there is one with better spec's available, but looking at the spec's for these oscillators,
> I can not find much info about this behavior.
> So I wanted to use my external GPS controlled 10MHz standard, but this gives me problems off not stable locking to the Hermes board.
> Changing the R141 from 100 to 50Ohm did help, but still a jump one in a while.. 
>  Bert
> 
> 
> Op 18-5-2013 8:50, John Marvin schreef:
>> ***** High Performance Software Defined Radio Discussion List *****
>> 
>> 
>> 
>> I think there is a misunderstanding here. When I was referring to small jumps of 0.5 Hz (perhaps larger in the 10/6m band) I was referring to the behavior of the TCXO when it is enabled. If you have enabled the external clock input then the TCXO is no longer involved in providing a 10 Mhz reference to the fpga.  If your GPSDO is not locking properly then you are switching back and forth between your GPSDO providing the 10 Mhz reference, and no 10 Mhz reference. When there is no 10 Mhz reference then the 122.88 Mhz VCXO is just free running, which can easily be 30 to 40 Hz off. Hopefully an adjustment to your signal level will fix the locking problem.
>> 
>> John
>> AC0ZG
>> 
>> On 5/17/2013 11:28 PM, H.A.Meijer wrote:
>>> ***** High Performance Software Defined Radio Discussion List *****
>>> 
>>> 
>>> 
>>> Hi,
>>> thanks for your thoughts about the freq jumps from the 10MHz osc.
>>> You are talking about "just 0,5 Hz' but my Hermes is jumping 30 to 40 Hz when on 10/6 mtr and with transverters (MF=28MHz) use.
>>> This is very annoying and for me not the so called "high performance"  I'm looking for.
>>> 
>>> I did change the R141 and still see that is has some locking problem to my external 10MHz, now and then.
>>> I will do some measurements at that circuit, maybe my 10MHz level is to low..
>>> 
>>> Bert
>> 
>> 
>> 
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