[MRCA] ProgRock Limitations, was: QRP Military Radio Magic

[Rob Flory]

Hi Steve,

Thanks for your comments.

I'm not quite a fossil when it comes to digital tech, but damn close.   I
was able to program the ProgRock with Anthony's live tutorial at the MRCA
Gilbert meet and the QRP Labs web page.

The harmonic issue seems to be manageable in the context of the TRC-77, as
there are tuned circuits following it, and as a QRP rig any harmonics are
going to be really weak.

I have experienced an undesired but not problematic spurious frequency
response.  I am used to hearing sideband around 7039 from VE or DX stations
so I was not alarmed when I heard some monkey chatter.  I noticed, though,
that the station was not signing wawa wawa wah but rather wawawawa wah, so
I tuned it in with the clarifier and it was not Victor Echo Three but W One
calling the Mass/RI phone net.  I looked up the net and I was hearing
something from around 7243kc.

That's only one time I have experienced an identifiable spur, and I plan to
look into whether tuning and/or injection level helps.

In the meantime I am still having a lot of fun with the set as configured.

I was getting ready to get back into crystal grinding to make matched pairs
until Anthony brought forward the ProgRock option.

When I was doing crystal controlled VHF work I got into crystal etching for
its precision, with some coaching, maybe from WB2JWU and/or WA2EJT or
both.  Maybe that would be a good approach to the PRC-74 problem.

73, Rob

On Tue, Oct 1, 2024 at 6:43 PM sbjohnston--- via MRCA <mrca at mailman.qth.net>
wrote:

> I have really enjoyed all the QRP Labs kits I've built.  Just a couple
> weeks ago I put a 10m WSPR beacon on the air from here on Kauai using
> another Ultimate 3S kit and a low-pass-filter kit.  A successful result and
> quite economical.
>
> I've used ProgRock2 devices several times as a crystal substitute, and I'd
> like to share my experiences:
>
> -  The USB programming requires that you know how to use a terminal
> program to talk on a USB port.
>
> - The output is a harmonic-rich square wave, so filtering may be necessary
> in some applications.  QRP Labs has very inexpensive low pass filter kits
> that may be helpful.
>
> -  These are microcontroller/synthesizer modules and as such will spray
> significant radio noise.  When used in a transceiver or receiver you should
> be ready for some reception interference.  Shielding and filtering the
> lines into the ProgRock2 can help, but remember you are directly coupling
> the unit into your receiver.  If a birdie from the ProgRock2 happens to
> fall on a desired channel it might be a difficult problem.
>
> -  If you are considering using a ProgRock2 in an FM transmitter
> application, you will need to make sure the rig uses phase modulation and
> not direct-FM.  Direct FM wants to frequency modulate the crystal
> oscillator, and if you use a ProgRock you can't do that.
>
> I don't want to discourage people about the ProgRock2 - it is a very handy
> device and have successfully used them in projects.  But I have also been
> frustrated and given up on that approach.  It is important to realize the
> reality of the situation and manage one's expectations.
>
>
> Steve WD8DAS
>
> sbjohnston at aol.com
> http://www.wd8das.net/   <http://www.wd8das.net/>
> http://af4k-crystals.com/
> --------------------------------------------------------------------
> Radio is your best entertainment value.
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>
>
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