[amsat-bb] Any experience with low-cost 433MHz transverter from transverters-store?
ag6ie at wolak.net
Tue Feb 2 05:06:23 UTC 2016
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?
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