[hpsdr] Angelia external clock input?

[John Laur]

Jim, the Apache-Labs daughterboards are free which is why they are not
listed with a price. You have to pay a shipping charge. However I
recommend that you order one that you also purchase the 0.1ppm TCXO
option which does have a moderate cost, but is otherwise a worthwhile
upgrade.

My board is a layout of Chen W7AY's Hermes Reference Oscillator
http://www.w7ay.net/site/Hardware/HermesReferenceOscillator/index.html
that fits Angelia, so he deserves the credit for it, not me. I have
not had time to validate the layout, but as soon as I do I will pass
the eagle files to Chen for publication and make the OshPark link
public. I should have a stable reference source within the next couple
of weeks to do the required calibration and testing.

I believe Chen's design is superior, but certainly the Apache Labs
boards do work fine.

73, John K5IT

On Tue, May 5, 2015 at 8:40 PM, Jim Barber <barberaudio at gmail.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Thanks, Glenn. That's definitive enough for me.
>
> I've been in touch with John, K5IT about the Angelia board he's working on.
> I've seen boards on the Apache site as well, but they don't have prices
> listed,
> just "$" with nothing after .  Not sure what that's all about .
>
> Thanks for the reply,
> Jim N7CXI
>
>
>
> On 5/5/2015 5:42 PM, Glenn Elmore wrote:
>>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>> Jim,
>> I can't provide any information as to a consensus but after studying my
>> new Angelia and analyzing why it didn't lock properly with an external
>> input, I came to the conclusion that the differential pair external-10MHz
>> condition circuit, which is essentially RTL, does not have sufficient drive
>> capability to provide the fast edges into the PC track/TL and loading of the
>> FPGA input.
>> Mine almost worked on receive but came unglued on transmit.
>>
>> I wrote to Apache Labs who kindly sent me a new board - just installed
>> last night.  This board appears to solve the problem by inserting a fast
>> totem-pole output logic driver between the diff pair and the FPGA
>> line/input.  The result is that my Angelia now works properly on both
>> receive and transmit.
>>
>> I can see no combination of input levels or wave shape that will likely
>> accomplish this same goal.  I think you need a daughter board or the
>> equivalent.
>>
>> Just my opinion, not a consensus.
>>
>> Glenn n6gn
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