23-12-2023, 06:02 PM
(This post was last modified: 23-12-2023, 06:04 PM by Mike Watterson.)
I have an older Visual Analyser on an old XP in the Workshop
https://www.sillanumsoft.org/
The AC97 motherboard chips may or may not be any good depending on associated HW.
https://www.sillanumsoft.org/download.htm
External USB sound boxes / adaptors vary from studio quality to junk.
My Rigol replaced an old HP141T that died, though it had no tracking generator. There are many variations.
Though I had a 10 GHz plug-in for the HP141T, I decided the 19 kHz to 1.5GHz plus TG was enough
https://www.amazon.de/-/en/gp/product/B00CLWJA38/
An RLB is maybe over €500, some are near €1000. I found a 4 port hybrid coupler that works quite well (in a drawer of junk). One sample port has 50 Ohm sealed on it. Something like that can be bought for under €100. The same drawer has an excellent low power DC switched attenuator rated DC to 3GHz that has 10, 20, 20 and 20 dB. So that will do 0 dB to 70 dB in 10dB steps. The Rigol's TG does 0dB to -20 dB in 1 dB steps, so I can use it either as a static generator or wobbulator (IF) or tracking generator (with power sweep option of 0 to -20dB) 19kHz to 1.5GHz at 0 dB to -90dB with 1 dB steps (50 Ohm). No AF modulation, but I'd hardly ever use that and I have the two old valve signal generators with AM or CW 100kHz to 60MHz.
The Spectrum Analyser part can be 50 or 75 Ohms and using DC block splitter and a €45 sat box for volts and 22 kHz I was able to align a sat dish with four quattros and a multiswitch on 9E, 13, 19E and 28.2E, even though at 1.5GHz max the full range can't be seen. An actual satellite receiver is only any use if you have enough signal for a lock and know which bird it is.
I have also a NanoVNA and it's got a bit of a learning curve and can be misleading. Higher frequencies are done using the generator harmonics! Also it has no RLB (return loss bridge) so is using a hybrid coupler. Handy to check aerials. I found that to cut multiple 1/4 wave lengths of 75 Ohm and 50 Ohm coax the best way to find the initial length was to solder the open end to an SMA and hunt with a pin to short the cable 1/4 wave away at the band of interest. Tables of velocity factors are not exact enough, partly because the randomly bought cable may not be same dielectric. I hope to make up a switch box fed from a crossed yagi with dual feed for 145 MHz so I can select +45, -45, vertical, horizontal, left circular and right circular. The S/H aerial as it came was disassembled with some broken insulators (uses rods insulated from boom) and the two driven elements had interconnected pair of gamma matches. I replaced socket on one gamma match so that the aerial has two feeds, a +45° and -45°. The NanoVNA allows one to adjust the position of the gamma match. I also used the NanoVNA to tune a 70MHz vertical and length of four radials (about 1m each obviously!) based on recycling a Watson 300. It was too short so the top cap was cut off and some white PVC pipe with an end cap extended it.
After much experimenting and calculations I decided that a dual band 6m & 4m colinear/vertical is nearly impossible. The 6m, 2m and 70cm or any combination is more feasible.
https://www.sillanumsoft.org/
The AC97 motherboard chips may or may not be any good depending on associated HW.
https://www.sillanumsoft.org/download.htm
External USB sound boxes / adaptors vary from studio quality to junk.
My Rigol replaced an old HP141T that died, though it had no tracking generator. There are many variations.
Though I had a 10 GHz plug-in for the HP141T, I decided the 19 kHz to 1.5GHz plus TG was enough
https://www.amazon.de/-/en/gp/product/B00CLWJA38/
An RLB is maybe over €500, some are near €1000. I found a 4 port hybrid coupler that works quite well (in a drawer of junk). One sample port has 50 Ohm sealed on it. Something like that can be bought for under €100. The same drawer has an excellent low power DC switched attenuator rated DC to 3GHz that has 10, 20, 20 and 20 dB. So that will do 0 dB to 70 dB in 10dB steps. The Rigol's TG does 0dB to -20 dB in 1 dB steps, so I can use it either as a static generator or wobbulator (IF) or tracking generator (with power sweep option of 0 to -20dB) 19kHz to 1.5GHz at 0 dB to -90dB with 1 dB steps (50 Ohm). No AF modulation, but I'd hardly ever use that and I have the two old valve signal generators with AM or CW 100kHz to 60MHz.
The Spectrum Analyser part can be 50 or 75 Ohms and using DC block splitter and a €45 sat box for volts and 22 kHz I was able to align a sat dish with four quattros and a multiswitch on 9E, 13, 19E and 28.2E, even though at 1.5GHz max the full range can't be seen. An actual satellite receiver is only any use if you have enough signal for a lock and know which bird it is.
I have also a NanoVNA and it's got a bit of a learning curve and can be misleading. Higher frequencies are done using the generator harmonics! Also it has no RLB (return loss bridge) so is using a hybrid coupler. Handy to check aerials. I found that to cut multiple 1/4 wave lengths of 75 Ohm and 50 Ohm coax the best way to find the initial length was to solder the open end to an SMA and hunt with a pin to short the cable 1/4 wave away at the band of interest. Tables of velocity factors are not exact enough, partly because the randomly bought cable may not be same dielectric. I hope to make up a switch box fed from a crossed yagi with dual feed for 145 MHz so I can select +45, -45, vertical, horizontal, left circular and right circular. The S/H aerial as it came was disassembled with some broken insulators (uses rods insulated from boom) and the two driven elements had interconnected pair of gamma matches. I replaced socket on one gamma match so that the aerial has two feeds, a +45° and -45°. The NanoVNA allows one to adjust the position of the gamma match. I also used the NanoVNA to tune a 70MHz vertical and length of four radials (about 1m each obviously!) based on recycling a Watson 300. It was too short so the top cap was cut off and some white PVC pipe with an end cap extended it.
After much experimenting and calculations I decided that a dual band 6m & 4m colinear/vertical is nearly impossible. The 6m, 2m and 70cm or any combination is more feasible.
