- Chineses TCXO for 28 MHz IF 2M transverters
Re: Chineses TCXO for 28 MHz IF 2M transverters
Robin Midgett <K4IDC@...>
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Alternatively, use a LPF such as these from QRPLabs to derive the sine from the square wave. I did that for the Si570 synthesizer output to drive an old GE MASTRII transmitter chain to make a 6m beacon; works great.
Robin Midgett K4IDC
On Sat, Dec 8, 2018 at 6:11 PM John Klem <klemjf@...
I have been interested in similar low-cost TXCOs, but concerned
about what's in the package. It would be very interesting to see
an output spectrum.
Given that you are probably driving a mixer that is basically a
diode switch, it's not clear to me that a square wave would be a
problem. Even with a sine wave LO, you are creating mixing
products around multiples of the LO frequency, and any decent
amount of filtering downstream of your mixer takes care of that
problem. Does anyone know more about this topic? I have
considered a 222 transverter LO using a MEMS oscillator chip
(square-wave output), and was thinking that LO filtering would not
On 12/8/2018 9:22 AM, Keith Morehouse
I don't know how good these are or what the
ultimate output level is, but this is the frequency you need
if you want to stabilize your older DEMI (or whoever) 144
MHz transverter. They are being sold by the pair, so you
have one to break and one to use. They shouldn't be too
hard to integrate into almost any 28 MHz IF transverter.
Look up the specs of your mixer for LO power requirements,
check this one and then either pad it down or, more likely
use it as is or drop a 0.99$ MMIC in as a buffer amp. I am
sucked in for a pair.
I've had a EBay search active for this frequency TCXO
for two years and this is the first usable (hopefully)
unit that has come up. I messaged the seller to make SURE
it was a sine-wave output (most of these are clock
oscillators with TTL or CMOS square-wave's output) and he
verified it was sine-wave. If not, I guess I could legit
return it by showing EBay his message.
I bought a TCXO advertised just like this as a drop-in
for a Yaesu FT817 and it worked fine and was dead on freq,
out of the package. It was 20% the cost of a Yaesu equiv
Calmesa Partners G.P.
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