Hi Andy,
I would connect a sig gen to the RX port and probe the port with a storage
scope.
Feed the low power TX port into a 50 Ohm termination and probe it with the
second
channel of the storage scope.
Then key the TX and look if the RX port is shorted during transmission and if
so,
if there's sufficient delay between RX port shorting and start of transmission.
73
Clemens
DL4RAJ
Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Andy Talbot
>Sent: Sunday, November 18, 2018 6:12 PM
>To: [email protected]; rsgb_lf_group
>Subject: LF: Elad FDM-DUO on LF
>
>Does anyone use the Elad FDM-DUO on LF with external power
>amplifier and separate Tx / Rx antennas?
>
>This transceiver is perfect for the LF / MF bands in having a
>separate low power Tx output port supplying a very clean 0dBm
>which could drive a high power amplifier for linear mode operation.
>
>But I have one big issue with this, and don't yet knw if I
>need tgo incorporate separate protection circuitry.
>
>WHen the low power port is used on transmit, there is no
>information available as to what the radio does with its
>receive antenna port. For all we know, it could remain
>connected to sensitive circuitry. It would be vary careless
>if the designers had allowed this to occur, but no details are
>available and asking on the Elad Group gave no replies.
>
>My active E-probe antenna sits under the Tx antenna and when
>radiating 700 Watts is quite happy and survives this, sending
>back a very distorted +27dBm of signal back up the Rx port in
>retaliation. The SDR-IQ I used to use could survive this (I
>found out by accidental trial-and-error it could survive)
>
>But at £900, I'm not going to use trial-and-error to see how
>this transceiver copes.
>
>Technical support for this radio is very poor.
>
>Andy
>
>www.g4jnt.com
>
>
>
>
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