Background noise on 80m - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Sparky67 · 4th Sep 2023, 9:33 am

The wide-band noise level across the bottom half of HF here is over S9 on the meter. I found a few dB of attenuation, between 6 and 10dB, in the Rx antenna feed makes most weak signals much more readable. I can also switch off two in-house contributors to the S9 noise, the extractor and under-cupboard lights in the kitchen, remotely using a (modified) Sonoff wifi mains switch. Saves a walk downstairs each time!! With 6dB in cct and the kitchen PSUs off the noise reduces to around S1. Take the 6dB out and it up to S7/8 again…!

Bazz4CQJ · 15th Sep 2023, 8:25 am

So, much of the noise comes from within the house. What is the antenna and RX being used?

I haven't done any further investigation at this end yet, but I did recall that I have an Alinco scanner which may well be a slightly better receiver for noise direction finding than the Sony (it has an S meter).

B

Sparky67 · 15th Sep 2023, 8:41 pm

Bazz, the antenna is a quarter-wave end-fed for 60m, fed against a counterpoise. No unun fitted after the SG230 auto tuner as most of my transmitting is on 60m. Receiver is an Icom 718. My shack is upstairs at the back of the house and the far end of the antenna is supported in a cherry tree, just a few feet away from some houses which have recently been built behind us. We’re in a typical suburban-type location with houses either side as well and overhead phone lines at the front. So pretty much surrounded by potential noise generators…!

I have switched everything off in the house one at a time to try to find other internal sources. Found my laptop PSU is very noisy but nothing else is creating significant interference.

Martin

4th Sep 2023, 9:33 am	#21
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 555	Re: Background noise on 80m The wide-band noise level across the bottom half of HF here is over S9 on the meter. I found a few dB of attenuation, between 6 and 10dB, in the Rx antenna feed makes most weak signals much more readable. I can also switch off two in-house contributors to the S9 noise, the extractor and under-cupboard lights in the kitchen, remotely using a (modified) Sonoff wifi mains switch. Saves a walk downstairs each time!! With 6dB in cct and the kitchen PSUs off the noise reduces to around S1. Take the 6dB out and it up to S7/8 again…!

15th Sep 2023, 8:25 am	#22
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,739	Re: Background noise on 80m So, much of the noise comes from within the house. What is the antenna and RX being used? I haven't done any further investigation at this end yet, but I did recall that I have an Alinco scanner which may well be a slightly better receiver for noise direction finding than the Sony (it has an S meter). B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

15th Sep 2023, 8:41 pm	#23
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 555	Re: Background noise on 80m Bazz, the antenna is a quarter-wave end-fed for 60m, fed against a counterpoise. No unun fitted after the SG230 auto tuner as most of my transmitting is on 60m. Receiver is an Icom 718. My shack is upstairs at the back of the house and the far end of the antenna is supported in a cherry tree, just a few feet away from some houses which have recently been built behind us. We’re in a typical suburban-type location with houses either side as well and overhead phone lines at the front. So pretty much surrounded by potential noise generators…! I have switched everything off in the house one at a time to try to find other internal sources. Found my laptop PSU is very noisy but nothing else is creating significant interference. Martin