[Lf] [Fwd: LF: AOR 7030 sensitivity at VLF]

[Andre' Kesteloot]

Alan Melia wrote:

> Hi all, John, G4CNN, raised the point of the sensitivity of the AOR 7030
> receiver, which is specified to go down to " 0Hz" !!  I knew it fell of a
> bit as SAQ was nowhere near as strong on the S-meter as I expected it to be.
> So I carried out the measurement tabulated below this evening using a
> Marconi TF2002B down to 10kHz, using the attenuator. Below 10kHz I used a
> Farnell DSG1 Synth audio gen with 10dB step attenuator and a pot to
> interpolate with a moving coil meter reading (both relative to 50 ohms). The
> frequency is that shown on the generator, and the measurement was made in
> LSB mode with a 1000Hz tone. So the rx was indicating 1kHz higher than the
> generator. The internal preamp in the 7030 was switched in. The generator
> was adjusted to read S9 on the LCD scale (which has a resolution of 1dB,
> although the scale is not quite that linear)
>
> Frequency            TF2002B            DSG1
>     in kHz                 in uV               in mV
>     137                        45
>     100                        45
>      75                         45
>      50                         70
>      35                         80
>      25                        220
>      20                        900
>      15                       5000
>      10                     80,000               70
>       9                                             150
>       8                                             325
>       7                                             650
>
> The ultimate sensitivity of my 7030 using Spectrogram or Spectran is
> approximately
>  -80dB relative to S9 at 136kHz. A good audio preamp would be better below
> 10kHz!!
> What should we be aiming at as a practical usable sensitivity, considering
> we will probably be using milliHz bandwidths?
>
> Cheers de Alan G3NYK
> Alan.Melia at btinternet.com