Zack - Well at the price they are selling for, they are probably worth getting
to just to play with and satisfy your curiosity. The bare board is only $52
including shipping. Even if you don’t purchase the transverter, the
switching/attenuator board at $15 with shipping has lots of applications itself
and is reasonably priced.
The mixer and RF amplifier are BF998 dual gate MOSFETS which is older
technology. The BF998 is a reasonable RF device though if the circuitry around
it is designed properly and will probably be OK under most conditions. The
biggest issue I see with the receive portion of these transverters is the
single stage bandpass filtering. The BF998 as a mixer is certainly not as good
as a double balanced mixer, but still not terrible. This is certainly good
enough where activity is low or one is located at a remote site. I look forward
to the day when activity on 222MHz is high enough that these transverters would
be inadequate on receive. :^)=
The Mitsubishi RD15HVF1 final, on the other hand, is a modern device designed
especially for 12VDC operation. Most power MOSFETS require much higher voltage
to be as efficient and don’t have as big a linear range when operated at 12Vdc.
I don’t think there is much better out there device wise in that power and
price range.
Thanks for the info on the 222MHz power module and the comments on the
transverters. See you at Dayton? - Duffey KK6MC
On Feb 15, 2017, at 8:15 AM, W9SZ wrote:
>
> I've been curious about these, but not enough to buy one. Schematics are
> available on-line. Looking them over, I see they contain "older"
> technology. If I were to design one of them these days, I'd use somewhat
> different parts and configurations.
>
> I use the W1VT no-tune transverter for 222 MHz. It uses three boards - one
> for the 194 MHz LO and two identical boards that can be configured for
> transmit or receive. They also allow several possible configurations on
> receive depending on whether you're in a high-RF environment or not. They
> are excellent performers. An additional power module gives me 10 watts
> output.
>
> By the way, this eBay sale is for the same module I use. I bought one to
> have a spare. Very good price and the one I got works fine. You can squeeze
> more than 10 watts out of them, but I throttle it back because I'm QRP
> Portable in most contests.
>
> It's eBay item 351966348973.
>
> 73, Zack W9SZ
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|