Re: LF: Re: MiniWhip antenna, fiber optic TEST SIGNALS NEEDED on 630m WSPR

["Roelof Bakker" <roelof@ndb.demon.nl>]

Hello Stefan,

Before using an optical link with an active antenna, I have been testing  
it with a spectrum analyzer.
A FSH756V was used as optical transmitter and a FSH350V as optical  
receiver.
Instead of a BF862, a J310 was used in the transmitter.
The FSH350V was followed by a standard mini-whip buffer amplifier.
The FSH756V and FSH350V are not suitable for HF use, I'm afraid.
These are rated for only 15 kBd.

The system was tested between 50 kHz and 10 MHz with a 1 meter and a 19  
meter long optical cable.
I found that the cable loss varied from 0.48 dB/m at 50 kHz to 0.35 dB/m  
at 10 MHz.
As it works now, loss is rather severe; with a 1 m optical cable I found:

50 kHz:   5.4 dB
100 kHz:  6.7 dB
200 kHz: 11.0 dB
300 kHz: 14.3 dB
400 kHz: 16.7 dB
500 kHz: 18.7 dB

Using a 19 meter long optical cable another 8 dB should be added to these  
figures.
None the less I will try to carry out a test with a mini-whip on 400 kHz.
To be continued.

73,
Roelof Bakker, pa0rdt