[McHUG] TX Modules Need Further Inspection

[Peter Morton]

Just thinking.

The Si571 can be frequency modulated.  The voltage control input has a 10 
KHz bandwidth and the modulatation sensitivity can be set as high as 356 
ppm/V (about +/-75 KHz at 433 MHz with 2 volt peak-to-peak Vc input). 
You'll need about 15 dB gain following the Si571 to get 10 mW to the antenna 
(and harmonic filtering, of course).

I assume you want FM in order to run packet.  If you can get away with FSK, 
Hope RF (Beijing) makes a number of 433.92 MHz FSK transmitter modules (see 
http://www.hoperf.com/rf_fsk.asp).  Futurlec sells these modules.  See: 
http://www.futurlec.com/Radio.shtml.  (The RFM01 sells for $5.90.)

-Pete

----- Original Message ----- 
From: n3sb at qis.net
To: <pat at patkilroy.com>; "MicroController Ham User Group - Physical 
Computing for Ham Radio" <mchug at mailman.qth.net>
Sent: Monday, December 22, 2008 9:17 PM
Subject: Re: [McHUG] TX Modules Need Further Inspection


Hi Pat;

The module I got from you appears to be a TX433B.

These modules are really designed for On-Off Pulse modulation. We've been 
lucky
so far to get something out of them that can be heard on an FM receiver. It
would be nice to get FM out of one of these. That's one thing that needs to 
be
looked at further.

Have a safe trip in 8-Land, and Happy Holidays!

73; Steve, N3SB

Quoting Pat Kilroy <pat at patkilroy.com>:

> Hi Steve,
>
> I more than loaned you the module, forgive me
> for the poor communication.  Consider it yours.
> But remind me *which* module or modules you have ...
>
> The TX433 is the flea power unit, 10mW output max.
> The TX433B module features 500mW but of course it
> comes with a "more battery" mass requirement.  (I
> always loved Rich's brilliant "double coin cell"
> idea in the original PICetSat module, so I won't
> give up on the smaller transmitter.)
>
> The B version also adds an extra pin, the E/D Pin,
> to Enable and Disable the xmtr itself or the audio
> input pin.
>
> Transmitter Web page:
> http://store.qkits.com/moreinfo.cfm/TX433B
>
> MAIN POINT
> I will give you, Rich and Pete either one or both
> types before I head to Eight Land for the holidays
> if you think you may have time to experiment with
> them and learn more about them.  After all, the
> spec sheet is lacking and customer support does
> not seem to exist.  We need more insight on these
> little devices!
>
> Guys, please let me know what you think of my
> offer.  I must get them to you soon.
>
> Cheers,
>
> Pat
>
> > -----Original Message-----
> [snip]
> >
> > Hi Pat;
> >
> > I have a couple TX-433 modules - one of which is a module you lent to me 
> > a
> > couple months ago. It'll be interesting to see if these modules can be
> coaxed
> > to send packet tones.
> >
> > 73; Steve, N3SB
> >
>
>
>
>
>
>
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