u/systemdev_

Built a new dish with DL4MEA feed for 1420 MHz. This radio telescope will be used for sky mapping, using only the earth spinning and daily azel correction

It starts blinking green for a few seconds after turning on, then it blinks yellow. When I insert a tape, it makes some knocking sounds, then stopes.

My system has a strange behavior. In the random moment, there happens a harmonics. I’ve tried different sdrs and lnas - rtlsdr v3, v4, Pluto SDR, nooelec sawbird+ h1, htool ht004. I’ve tried different antennas - tplink wifi antenna, circular waveguide with 1.5 parabola. My coax is RK50-7-11 with N connectors. I have tried to power my sdr from pc, usb power supply, power bank and to power my lna with bias t (from sdr, transformer) and without (from power bank).

I have tried:

1. Turning off the electricity at home - didn’t helped

2. running entire setup on the street far from home without coax with my laptop - also didn’t helped

3. make an rfi with my phone making a call, with my baofeng on 433 MHz and with my icom ic78 - phone calls and icom ic78 doesn’t affect, transmission on 433 MHz near the cable or antenna makes the noise floor higher. But it doesn’t behave like on the video

4. pointing my waveguide to the floor - the problem keeps appear

5. using an 15db attenuator before the sdr - didn’t helped.

I live on the outskirts of the small city with ~150.000 population in the private house. The antenna is about 10 meters from the house and about 30m from the nearest neighbor.

The problem begun appearing since the autumn 2025. It appears only with an enabled LNA.

During the half of the year I haven’t found any reasons or methods to solve the problem.

Thanks for any help.