Yes, I have. Though for Mode J, I would have a filter on TX or else the third harmonic certainly would overload it.
I haven’t extensively done this, but I haven’t encountered any problems when doing it. I would recommend using a diplexer or filter on the input. Just be sure you use something that’s very low loss.
73,
Paul, N8HM
On Fri, Jan 11, 2019 at 16:50 Ryan Noguchi via AMSAT-BB [email protected] wrote:
When you say "without any protection on the input" do you mean you aren't using any diplexer or filter (external to the SDR) on the input RF path to the SDR, even for Mode J?
73, Ryan AI6DO On Friday, January 11, 2019, 10:03:30 AM PST, Paul Stoetzer < [email protected]> wrote:
I've used my AirSpy Mini and FCD+ without any protection on the input without any damage, but your mileage may vary!
73,
Paul, N8HM
On Fri, Jan 11, 2019 at 12:55 PM Rolf Krogstad [email protected] wrote:
I use a diplexer, such as the MFJ-916B or equivalent, and it provides enough isolation of the 2 meter signal to prevent problems.
Rolf NR0T EN34
On Fri, Jan 11, 2019, 11:14 AM Ryan Noguchi via AMSAT-BB <
wrote:
Is a transmit/receive switch necessary, or would a simple duplexer suffice? Something like the MFJ-916B offers 55dB or better isolation,
and
fairly low loss (0.2dB). It's a lot cheaper and more convenient to set
up.
My SDRPlay RSP1A arrived yesterday and I got it and my FT-857D working with CAT control using SatPC32 last night. I haven't worked a pass
with it
yet, though; maybe this weekend. The RSP1A is rated for 0dBm
continuous,
10dBm momentary. The antenna is a dual-band Elk in the attic on a TV rotator, so there is no benefit of interantenna isolation. If I assume
the
duplexer's spec value of 55dB isolation, that would attenuate even 250W input down to less than 0dBm, correct? Patrick WD9EWK had commented on
the
subject of SDR protection in a QRZ.com posting, and has used a duplexer instead of a T/R switch with his SDRPlay SDR:
https://forums.qrz.com/index.php?threads/kenwood-ts-2000-in-full-duplex-mode...
Would love to know if my math is wrong, if the RSP1A's spec isn't trustworthy, and/or if there are any other considerations that make a transmit/receive switch better (or necessary) than just a duplexer,
before
I let the magic smoke escape.
Thanks and 73, Ryan AI6DO
On Friday, January 11, 2019, 8:31:34 AM PST, saguaroastro < [email protected]> wrote:
Kevin, I've be looking at this. MFJ-1708. There are several versions. So look
the
up on Hro to compare
73Rick Tejera (K7TEJ)Saguaro Astronomy
ClubWww.saguaroastro.orgThunderbird
Astronomy ClubWww.w7tbc.org
-------- Original message --------From: Kevin Zari [email protected] Date: 1/11/19 06:40 (GMT-07:00) To: [email protected] Subject: [amsat-bb] Protecting SDR For those of you with an SDR dongle, for example the Funcube Pro +,
how
do you protect it from not being damaged by TX energy? I’m thinking of hooking mine up to the 70cm antenna in my M2 LEO pack while I TX on
the 2m
antenna and was afraid I’d overload the SDR. I see folks using them for their RX on linear birds, so I’m just wondering how you have them
hooked
up. Thanks in advance for your advice.
-Kevin (KK4YEL)
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