[NLRS] Thoughts on VHF-UHF beacon hardware.

[Rolf Krogstad]

I just saw the following in the weeklyh "ARRL Contest Update" email
bulletin.
I don't think anyone has mentioned it in the thread yet.

73
Rolf  NR0T

The HobbyPCB RS-UV3 <http://www.hobbypcb.com/products/rs-uv3> is a tri-band
VHF/UHF building block providing an FM Transceiver on 144/220/450 MHz. It
plugs directly into an Arduino as a shield, but can also be used with other
3.3/5.0v serial capable computers like Raspberry Pi and Beaglebone. It
claims on-board support for beacon, repeater, single channel voice,
Echolink, APRS and Packet.



On Thu, Jul 16, 2015 at 12:14 PM, Doug Reed <n0nas at amsat.org> wrote:

>
>
> I've been debating with myself what might be the cheapest way to get a
> VHF-UHF beacon on the air without having to dedicate an expensive SSB
> rig to the task and without buying crystals. I keep coming back to
> using modes like CW or PI4/JT65/WSPR that work with a Class C RF
> amplifier, then use an old FM mobile as the TX and power amp. You can
> use crystal control, but crystals are getting difficult and expensive
> to buy. But it is fairly easy to do if the beacon controller also
> provides the frequency control and stability. The HansSummer.com
> Ultimate 3S controller can handle all of that, especially with the
> optional OCXO SI5351A oscillator and using GPS for frequency control
> and timing.
>
> I've been a bit more worried about how to do propagation RX monitoring
> from the same site, if I wanted to.... The FM receiver is useless for
> that, but with the SI5351A oscillator acting as a LO for the receiver
> front-end and mixer, I could feed the IF out to a "cheap" HF receiver
> such as a SoftRock, Minima, Pixie, or even a CB SSB radio. Anything
> that receives CW or SSB would work to feed audio to the sound card RX
> software for decoding. Another option would be to just use the FM
> receiver front-end as a filter with a RTL-SDR dongle as the
> receiver....
>
> If anyone wants to try this or other direct keying mods to build a
> beacon site, VHF and UHF crystal-controlled mobiles are available
> pretty much for the hauling. Nobody wants to buy crystals. 6M is a
> little harder to find because you have to be sure you get a "high
> split" radio.... In fact the problem may turn out to be that many or
> most of these mobiles are 110W radios and they seem like a bit of
> overkill for a beacon....
>
> One thing to remember, the FM mobiles were designed for intermittent
> duty, around 20% TX. Unless you reduce power, add fans and heat
> sinking, or built an intermittent TX beacon, you will have problems
> with overheating the TX. OTOH, I have successfully modified a 110W GE
> mobile to run FM repeater continuous duty with just extra heat
> sinking. I then added fans to be 100% certain and it ran for about 15
> years before being replaced with newer equipment.
>
> 73, Doug Reed, N0NAS.
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