Hello Luis
A link to which Ebay supplier you got the correct Ublox units from
would be great, I believe these are a bit of a mine field with fakes
and various specs abounding :) Thanks!
Wednesday, December 19, 2018, 1:42:09 PM, you wrote:
> Hi EbNaut
> My downconverter is based on NE602 and is crude simple. No filters,
> no gain stages. A bit deaf and birdie-rich
> but wanted to test it that way for EbNaut and check if it works. It
> is based on K0LR article you can find here
> https://www.qsl.net/k0lr/SW-RX/sw-rx.htm
> The LO based in Xtal and 74HC4060 is REPLACED by a series 10K
> resistor and series 100nF connected to the GPS output
> So, for the LO, a cheap uBlox GPS will provide both 120 or 125KHz
> for the LO and 1pps to discipline the soundcard
> You only need to connect the GPS to USB and use the uCenter
> software to configure the GPS outputs and save
> this cnfiguration as default for the GPS
> No worth to use the same GPS for Tx. It is so chip you sure can
> afford another one for Tx at 2x the frequency if you
> are using a D class PA
> -----Mensaje original-----
> De: [email protected]
> [mailto:[email protected]] En nombre de N1BUG
> Enviado el: miércoles, 19 de diciembre de 2018 13:01
> Para: [email protected]
> Asunto: Re: LF: Ebnaut receiver frequency stability qustion
> Hi Stefan, Luis, LF,
> Yes, yes! Please grab some paper and start drawing those circuit diagrams! ;-)
> The non-engineers have many questions...
> If I understand this correctly... with the NEO-M8T then I just need
> one module... use one time pulse pin for LO and the other one for 1
> PPM to discipline the sound card? Else with the NEO-6/7 or M8N I need two.
> For the older modules U-blox says they use a 48 MHz NCO and that
> the time pulse output will have less jitter if configured to a
> frequency which divides evenly into 48 MHz. So I guess 120 kHz...
> But I couldn't find any information about the oscillator frequency for the
> M8T. Does anybody know?
> What kind of mixer?
> Can filters help? Band pass filter on antenna input to mixer? LPF on LO to
> mixer?
> Probably more questions but since I am not an engineer and have
> never seen a diagram of this, I don't know what else to ask.
> Can the same LO and mixer be used for a tx up-converter?
> 73,
> Paul
> On 12/19/18 3:22 AM, DK7FC wrote:
>> Hi Luis, LF,
>>
>> I agree, this is indeed the most reasonable design. Using the same
>> here
>> ;-) but a 125 kHz LO, locked to GPS.
>> Maybe we should provide easy converter crcuits. A compromise between
>> high end and easy to build up, for the 'EbNaut-newcomers'?
>>
>> 73, Stefan
>>
>> Am 19.12.2018 07:39, schrieb VIGILANT Luis Fernández:
>>> Hi EbNaut
>>>
>>> I think that using expensive receivers is NOT the way to go. I'm
>>> using a simple mixer as downconverter. The LO is 120KHz generated
>>> from a uBlox GPS. So the 137KHz outputs as 17KHz and can be feeded to
>>> PC soundcard. The second channel of GPS provides 1pps to discipline
>>> the soundcard using Spectrum lab
>>>
>>> Not using filters at all and no amplifier stages. So there is room
>>> for improvement, but it works
>>>
>>> 73 de Luis
>>> EA5DOM
--
Best regards,
Chris mailto:[email protected]
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