[Lf] LF Receivers

[Andre Kesteloot]

DL4YHF at aol.com wrote:

> Hello,
>
> I once had the chance to compare an old IC735, an IC706 and a TS850
> running
> side-by-side connected to a tuned LF-antenna (150m long wire).
>
> Results:
> - TS850 with 500Hz and 270 Hz filter:
>   Could hear the grass grow   and   OH1TN call cq on 136kHz.
>   A fine rig, as already expressed by others (and in the LF handbook).
>
>   Considering the price I once paid for it, and for what it can be
> found
>   nowadays on the second-hand market, I would almost buy a second
>   one as a spare unit !
>
> - IC735:  quite deaf, some IM products audible which were not there
>   on the TS850. But still a nice rig on 160m and HF.
>
> - IC706 ( the 'old' one, no MK2, with 270 Hz filter):
>   Very deaf on 136kHz, no matter if the preamp is on or off.
>   Turning the VFO knob OR THE VOLUME CONTROL results
>   in a hissing sound, which stops after the motion.
>   Looks like the rig picks up some noise from its own serial interface
>
>   between the front panel and the microcontroller !
>   Hopefully the IC706 MK2 ( & -G) are better at 136kHz.
>   At 77kHz, I cannot even hear the DCF time signal transmitter near
>   Frankfurt...
>
> Some years ago, I compared the TS570 and the TS850 on HF for CW.
> There were severe blocking effects in the TS570 in a heavy crowded CW
> segment, because there is not enough selectivity in the early stages
> in the IF amplifier chain. The S-meter went up to S-9, but no signal
> could be heard because the DSP decided it was outside the passband.
> And, with modestly narrow CW filter settings the audio from the TS570
> sounded like a block flute, which is not very pleasant. Maybe there
> was
> something wrong with the DSP. We never did further investigations
> because the
> owner of the TS570 immediately traded it for a TS850...
>
> 73,
>  Wolf  DL4YHF.



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