M0SWS wrote:
What was your noise floor levels before putting the mains filter in line?
Yes , i am just setting things back up after some inactivity. Need to get some operating under way to see how things are etc.
Like you I've very recently got back onto the HF bands after a 10yr period of inactivity.
I resumed as a SWL'er about this time last year experimenting with various active whips and cheap loops. I'm in a typical suburban location, plagued with PLT devices outside the amateur HF allocations, the usual switched mode PSU stuff, some Solar Inverters, and VDSL2 leakage from the overhead telephone lines.
I finally settled on a MFJ-1886TR receiving loop to do all my radio snooping with. This is mounted on a small rotator so I can null out point sources of interference. It also works very well at peaking wanted signals, especially on lower frequencies.l
At the beginning of this year I decided it was time to get back into recklessly squirting RF all over the place. My antenna situation is a 30ft Random Wire for 40m to 10m for transmitting. This is arranged as a sloper with the feed point about 6ft agl and the distant end at about 30ft. I have a line isolator in the feedline about 20ft from the feed point. For receiving I'm using the MFJ-1886TR broadband loop. This is mounted four feet above ground and on a lightweight Yaesu Rotator.
Below are my receive figures as measured on my Icom IC-705
MFJ 1886TR Loop 40m-6m RW
160m S0 S0
80m S0 S5 (Increasing to S9 above 3755KHz)
60m S2 S9 (SMPS interference)
40m S0 S5
30m S1 to S2 S5
20m S0 S3
17m S0 S3
15m S0 S5
12m S0 S1 S0
10m S1 S5
These measurements were done at 13:45 with a bandwidth of 3KHz/SSB.
One of the reasons, as there were a few, why I shut up shop 10yrs ago was due in part to the amount of interference. Back then when I contacted the RSGB EMC people for advice it was suggested I try IRLP/Echolink and/or D-Star for out of country contacts. Last year I contacted them again and this time I was advised to canvas my neighbourhood to find the sources of interference. I knew what the sources of interference were/are, I was a signal's and protocol analyst with GCHQ before my health deteriorated, I was just after some assistance as OFCOM were not interested. The words Chocolate and Fireguard spring to mind, with the phrase "As much use as" tagged as a preamble.
It sometimes feels like an exercise in futility when chasing that illusive zero noise-floor level. In my case I had to go against my principles and shell out on a relatively expensive receive antenna instead of building my own, which I can no longer do due to health type stuff.
Edit. Apologies, I had created the table with proper spaces but these seem to be ignored by the website.