[McHUG] TX Modules Need Further Inspection

[Pat Kilroy]

Hi Pete and all,  

I don't know how to deal with FSK to get 
good packet tones or if we need strictly 
AFSK specified for the transmitter module.  
I hope you guys can help me through this 
phase of the design.  A UHF-equivalent of 
the Radiometrix HX1-144.390-3 (that Steve 
indentified last summer) at 200 to 300mW 
output would be perfect, but they are in 
the $50 price range -- much too high for 
expendable payloads.  

For now, I went to your www.hoperf.com 
suggestion and requested samples of the 
part numbers:

o HM-TR433/TTL
o RFM12BP-433
o HP03D (DIP version)

So, we'll see if I find free surprises 
in my mailbox upon my return after the 
holidays.  

In the mean time, the Si571 idea sounds 
really good.  Yet with the PICetSat II 
and the SDR kit builds with my student 
intern I might have too much on my 
plate to make headway with an Si571 
development myself.  Sure am glad we 
have a nucleus of a fine team here 
with great ideas that keep inching us 
forward.  

Thank you for your wonderful support!  

Cheers,

Pat
N8PK

> -----Original Message-----[snip]
> Message: 5
> Date: Tue, 23 Dec 2008 02:29:36 -0500
> From: "Peter Morton" <mortonph at comcast.net>
> Subject: Re: [McHUG] TX Modules Need Further Inspection
> 
> Fell asleep in my Lazy Boy, woke up and wrote my first reply.  
Shouldn't do 
> that until I'm fully awake.  Anyway, it should be +/-150 kHz, 
not +/-75 kHz, 
> deviation at 433 MHz with 2 volt peak-to-peak Vc input.
> 
> Also, in the second paragraph, it should state: The RFM02, 
not RFM01.  The 
> RFM02 is a transmitter, RFM01 is a receiver.  (Both sell for 
$5.90 each.)
> 
> -Pete
> 
> ----- preOriginal Message ----- 
> From: "Peter Morton" <mortonph at comcast.net>
> Sent: Tuesday, December 23, 2008 1:25 AM
> Subject: Re: [McHUG] TX Modules Need Further Inspection
> 
> > 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
> >
> > ----- pre preOriginal Message ----- 
> > From: n3sb at qis.net
> > 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