[amsat-bb] Any experience with low-cost 433MHz transverter from transverters-store?

[John Toscano]

No, if you are using an Icom IC-706MkII as your IF radio, it cannot operate
in full duplex mode. It CAN do split-band Tx/Rx, where you receive with the
built-in 2M section and transmit on 10 meters into the transverter to get
70 cm output. Or you can receive on 10 meters which becomes 70cm through
the transverter, and transmit on the built-in 2M section of the radio. But
you can't hear while transmitting. You would need a second radio or a radio
that is designed for full-duplex operation.

If you could find a deal on another IC-706MkII and add the 70cm transverter
to it, you'd then have a full-duplex station. A less expensive choice might
be an IC-703, which lacks the 2M band, but you only need 10M to run the
transverter anyway, so it would still make a nice matching pair of radios
that would work well for satellites. Or if you could find an IC-706MkIIg
then you'd have a nicely matching pair that includes 70cm on the new radio
and you'd use 2M on the older radio. Kind of pricey, but it's just a couple
of suggestions that could be made to work.

Another popular choice is a Yaesu FT-817. But then you would not need a
transverter since it has both 2M and 70cm bands already. You just might
need a PA to output more than 5 watts on mode UV, but no extra PA needed
for mode VU since the transmitter is the IC-706MkII in that mode.

Choces, choices, choices...
And we didn't even get into full-duplex radios like a Yaesu FT-847. (I love
mine!)

Happy shopping.
John, W0JT/5

On Mon, Feb 1, 2016 at 11:06 PM, Eric Wolak <ag6ie at wolak.net> wrote:

> Thanks, guys! It looks like the transverter kit includes an attenuator
> board to interface with a radio, so I'm set on that. These transponders
> work both ways, right, so if I can TX on 2m and RX on 70cm (through the
> transverter), then I can hear my own transmissions full-duplex, and I
> can make contact with someone TX'ing on 70cm?
>
> Are there any attributes that might be lacking with such a low-cost
> option, e.g. frequency stability or harmonics?
>
> On Sun, Jan 31, 2016, at 03:12 PM, John Toscano wrote:
> > The transverter itself can cover the satellite portion of the band.
> > The specs say it covers 432 - 442 MHz. The issue is that your IF
> > radio, the Icom IC-706MkII is what I believe you meant to say, can
> > tune high enough on the 10M band and above for RECEPTION at the
> > appropriate frequencies, but will not transmit above 30 MHz and
> > therefore, through this transverter, will not transmit above 435.0000
> > MHz. I know this from experience with my 222 MHz transverter.
> > Fortunately, on that band, 28-30 MHz -> 222-224 MHz, and the portion
> > of the band above that (224-225 MHz) is mostly FM repeater OUTPUTS,
> > which the radio will happily receive through my transverter.
> >
> > What you would need to do is defeat the 10M band transmit limits on
> > your IC-706MkII. You can probably find mods to allow that.
> >
> > Your other issue, which I also had to overcome with my 222
> > transverter, is that the transverter needs (accepts) only a very low
> > RF power signal on transmit (1-100 milliwatts) and your IC-706MkII is
> > happy to transmit 1000 times as much power, up to 100 watts. So you
> > will need to carefully interface the radio to the transverter to
> > insure that the transmit power is nice and low. In my case, my
> > transverter interface includes a source of negative voltage to feed
> > into the ALC input of the radio, which can drop the power low enough.
> > Interesting (=undesirable)  things happen if this ALC circuit fails,
> > or more likely, gets accidentally disconnected. I was fortunate, when
> > I transmitted 100 watts into my transverter by accident, I only fried
> > a 50 ohm resistor in the input circuit, and after replacing it, all
> > was good again, The same may or may not hold with this transverter.
> >
> > Good luck in your search for a solution.
> >
> > John Toscano, W0JT/5
> >
> > On Sun, Jan 31, 2016 at 12:46 PM, Eric Wolak <ag6ie at wolak.net> wrote:
> >> Hi folks,
> >>
> >> I'm trying to get on the air with the linear transponder satellites,
> >> and it looks like I need 70cm SSB capability to really get on the
> >> air. My Icom IC-796MkII can do SSB on 2m, but not 70cm, so I'm trying
> >> to find an affordable way to get 70cm SSB transmit.
> >>
> >> Does anybody have experience with these $100 transverter boards from
> >> Ukraine? It looks like they're tuned for the weak-signal/SSB end of
> >> the band and might require a bit of work to get up to 435MHz for
> >> satellites. Is 3-4W enough to be heard?
> >>
> >> http://www.ebay.com/itm/221871269275
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