¿ªÔÆÌåÓý

  1. BITX20
  2. Messages
Single Messages Topics Expanded Polls

Re: Poor mans spectrum analyzer #ubitx

Joe Puma
 

¿ªÔÆÌåÓý

I¡¯ve used my 100 watt radio next to a receive antenna for a rtl-sdr. I have fried am/fm filters and the sv1afn upconverter (a few times) but never the dongle. I have locked them up on the usb bus and had to unplug them to reset but that¡¯s about it. You will overload the dongle with an antenna going outside but without anything plugged in it might make it deaf for a ubitx with outside antenna and you in the house. A indoor whip seems doable or a piece of wire.?

I could see you using it as a comparative measurement tool. I¡¯ve used a rtl-sdr to look at characteristics of a filter with a cheap eBay noise source or using a directional coupler to measure swr of antennas. I¡¯m still an infant out here but I¡¯ve played with sdr¡¯s for a while. Baby toys for beginners I guess lol?


Joe



On Nov 3, 2018, at 5:45 PM, iz oos <and2oosiz2@...> wrote:

I don't know the circuit of the hackRF, but I wouldn't use any antenna connected to the SDR. You could fry its frontend unless it has some protection (I.e. Back to back diodes) at the antenna input. You just see a lot of overloading of your receiver. Having a 8bits ADC the dynamic range is similar to the RTL stick, 48db, so you need to attenuate a lot at least removing the antenna.


Il 03/nov/2018 18:53, "Nigel G4ZAL" <nigel@...> ha scritto:
I have no sophisticated bench test gear so I used my hackRF and the free Spectrum Analyzer software to 'look' at what my uBitx was transmitting whilst on FT8 on 7.074MHz and the result is quite disappointing although not unexpected.
uBitx was on an EFHW for 40M and the hackRF was on a short whip antenna.

I have some Axicom relays and shielded SMD inductors for L5/7 and will compare results after swapping out the bits and see if I can 'clean up my act' !

Nigel
Join [email protected] to automatically receive all group messages.