Transverters offsets
26 views
Skip to first unread message
Marcus PY2PLL
May 8, 2026, 9:11:32 AM (10 days ago) May 8
to SkyRoof
Hi Alex;
Is it possible on a future version include an "LO offset" at the SDR Devices config, or somewhere else under settings?
This will help to keep using RTL SDR at transverters IF port, taking advantage of its filtering, gain, noise figure and etc and keeping the superb Doppler correction.
It have been a challenge to avoid RTL overload during full duplex use. I already tested a couple filters at its input, traps and notches at both sides TX and RX but w/o success.
Few moments ago I connected an AirSpy Discovery + HDSDR to the 435MHz transverter RX port and it was way much better. I even tried to enable HDSDR built in CAT to OmniRig but I'm using rigctld to control Elecraft K3S so no ports available.
73 Marcus PY2PLL
Is it possible on a future version include an "LO offset" at the SDR Devices config, or somewhere else under settings?
This will help to keep using RTL SDR at transverters IF port, taking advantage of its filtering, gain, noise figure and etc and keeping the superb Doppler correction.
It have been a challenge to avoid RTL overload during full duplex use. I already tested a couple filters at its input, traps and notches at both sides TX and RX but w/o success.
Few moments ago I connected an AirSpy Discovery + HDSDR to the 435MHz transverter RX port and it was way much better. I even tried to enable HDSDR built in CAT to OmniRig but I'm using rigctld to control Elecraft K3S so no ports available.
73 Marcus PY2PLL
Marcus PY2PLL
May 11, 2026, 6:19:32 PM (7 days ago) May 11
to SkyRoof
Addendum: comparing the AirSpy Discovery both on 28MHz - as an IF device - or at 146MHz, I noticed that the audio level is vy low when compared to the level delivered by the RTL-SDR V4.
Some numbers: the output stream level on RTL is adjusted to -20 (reflects on the recording level as well), on AirSpy must be from -3 to 0 to have some output. There's no change on levels enabling or disabling AGC and under stage gains. Single Gain changes does not result in a usable RF Gain Slider action (is grayed). Again on Stage Gains only LNA accepts some change (0 or 6dB). RF only accepts zero.
73 Marcus PY2PLL
Some numbers: the output stream level on RTL is adjusted to -20 (reflects on the recording level as well), on AirSpy must be from -3 to 0 to have some output. There's no change on levels enabling or disabling AGC and under stage gains. Single Gain changes does not result in a usable RF Gain Slider action (is grayed). Again on Stage Gains only LNA accepts some change (0 or 6dB). RF only accepts zero.
73 Marcus PY2PLL
Reply all
Reply to author
Forward
0 new messages