[minima] Re: Parts list spreadsheet, still work in process

  • From: Thomas Sarlandie <thomas@xxxxxxxxxxxxx>
  • To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
  • Date: Mon, 17 Mar 2014 11:00:24 -0700

Jeremy,

For the inductor in the BFO, yes you can use the same core and windings as
for the other one. That is what I did.

Even if you are using an external amplifier you will probably need some way
to tell the amplifier which band you are transmitting on so it can turn on
the proper LPF. I don't think there is a standard way to do this. The
fanciest amp will automatically detect the frequency in the incoming
signal, some will use proprietary connections, some will require the user
to push buttons, etc.

73,
thomas


On Mon, Mar 17, 2014 at 7:10 AM, Jeremy Chase <jeremychase@xxxxxxxxx> wrote:

> Thomas,
>
> Thank you very much! I've incorporated your answers and have 2 followup
> questions. They are inline:
>
>
>>>    1. Can the 3u inductor near T3 be the same type as the inductors in
>>>    the filter?
>>>
>>> I guess you are referring to the inductor labelled "RFC" on Farhan's
>> schematic. Farhan said: "The RFC is 10 turns on FT37-43" According to
>> toroids.info, that is 35 uH.
>>
>>
>>
> I actually meant the inductor connectected to the 20Mhz crystal in in the
> BFO:
> https://www.dropbox.com/s/sa69fepffelwxfr/Screenshot%202014-03-17%2009.52.52.png
>
>
>
>>
>>
>>
>>>    1. What is the 'BAND SELECT' part connected to PD6 and PD7 of the
>>>    Arduino?
>>>
>>> This is a connector that would go to your power amplifier to switch
>> different band-pass or low-pass filters depending on the band that you are
>> on. The original idea was to use those 3 bits to select one band (3 bits =
>> 8 possibilities). We have since then explored other options and Farhan has
>> chosen the CD4017 option.
>>
>> Read "Bandswitching the low-pass filters" on the RF386 page for more info
>> on the new design that will only take one line:
>> http://www.hfsignals.org/index.php/RF386
>>
>
> So if the builder isn't planning to use an external amplifier they could
> omit this part. Is there a standard connector for BAND-SELECT chassis parts?
>
>
> 73 K2CHA
>

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