Static/noise

Had an issue with static on the set up at home,and I was not not having the same problem with the set in the car(same set) .
I did the unplug everything in the house routine slightly better but not a cure . On talking to one of the sparks at work he suggested that I try a isolating transformer and he gave me a lend of 1 it works ! The static is down about a 3 now on the meter and can be got better tweaking the rf Gain.
Hope this can help someone. I'm going to try to source one as I will have to return the one to work . Who could believe mains voltage was so dirty

Hi Davy,

Yes, the mans electricity supply is filthy as anything!

Many radio enthusiasts (Hams, CB'ers, SWL's etc.) have come across this problem and worked on all sorts of methods to alleviate themselves of such woes. My own shack mains supply now comes through hefty toroidal chokes to filter it all before it comes in (including the often forgotten Earth connection where there is noise aplenty!). I also spent some time finding a power supply where the negative output is isolated from the Earth connection which is something the typical 'sales' depts. can't tell you. I went for a linear type in the end as a switch mode added additional mess! 

Along with ferrites on interconnection leads such as power, coax, USB connections etc. (for my digi-mode forays) I got my background noise down to what seems like nothing compared to previous experiences. (Barely a glitch of the meter on 12/11/10m. )

Anything we can do to alleviate such issues greatly helps our radio activities.....you can't work 'em if you can't hear 'em.  


Amateur Radio operators have been onto this stuff for years now and I'll pop a link below that shows the 'problem solver' massive ferrite and build details of the 'whole shack mains filter' many utilise.

https://gm3sek.com/2019/10/11/clean-up-your-shack-2019/


Well done Davy with sharing your experiences and also for posting on the forum.  

All the best,
Victor

A friend of mine was suffering from terrible QRM and he fixed it by connecting his power supply to a 25M mains extension lead still coiled up on it's reel.. It worked a treat, I guess the 25M mains lead coiled up acts like a sort of choke. Try it you never know.

If it works,it works. I would never even thought of that , a massive induction coil my problem would be keeping an extension lead that long !
My boys +grass+flymo = many very short extension leads . Thank the man above for RCD breakers

Hello Chaps,

Some great info being given.

@Victor, Do you have a link to the transformer you use, please?

Thanks, John.

Hi John mate,

I didn't use a transformer, Davy here did.

I can only presume he used a 230V mains isolation unit akin to the types used on building sites, (the blue type not the 110V yellow one), and maybe he can confirm.

These units are manufactured by many and do seem pricey for what they are with such examples linked below :-

https://www.carroll-meynell.com/product-category/standard-products/portable-isolation-transformers/

(Hint, about £120 or so from the likes of Screwfix.)

Davy certainly seems to have had luck with one but might be nice to see if you can try one and return it for a refund if you get no dice.



My homebrew unit consisted of multiple T130-6 type toroidal transformers that I wound L, N & E coming in onto separate toroids. Additionally with a couple of common mode choke types on the L & N sides coupled with some class 'X' capacitors as well as some MOV's. (Metal Oxide Varistors.) 

Really not a project for the feint of heart or unfamiliar with electrical safety practices.
(Don't play with the mains there kiddies if you don't know what you're doing!)

Hence why I made a link to the GM3SEK project that is well documented on the old internet.
(Google for 'whole shack mains filter'.)

I did however change my power supply from the Sharman SM-30 switch mode type to the Sharman PS-LM40 which is a linear type and although a blind gamble at the time of purchase it turned out to be just the ticket once hooked up. (Isolated ground connectivity etc.)


The usual trick for homebase setups is to run your rig from a battery and then the typical 'switch off the mains' scenario, but when switching off the mains the 'dirty' Earth is still always connected spewing crap around your home. My setup filters the mains including Earth and the shack is supplied from that. (Technically a 'spur', tut-tut. ) You only have to hold an old AM/MW portable radio near mains cables, light switches etc. to hear the sort of hash the mains actually carries.

If supplying a typical external shack, (shed down the bottom of the garden, outbuilding etc.), via an isolation transformer or shack-filter then you too would be on a filtered 'spur' and hence away from any other rubbish usually found on the house mains supply.

Others, as inferred to later on in this posting may be running via a coiled extension lead and away from the house having a similar overall effect. Different setups may also include keeping everything away from the dirty mains and other electrically interfering devices by carefully placing antennas etc. as far away from your house (as well as neighbouring houses) as possible.


It certainly isn't always an easy task there John and I haven't even mentioned the abundance of additional ferrite material I had to place on my radios, laptop, monitors etc. to keep all the noise down!

Was all worth it though to finally get the low noise floor I now enjoy.  

(If I wasn't in a deep-dark-hole-inland-valley I might grab a bit more DX! Best to work with what you've got that bemoan it.)



Apologies for the typical 'waffle' but trying to convey as many thoughts as possible in the chance it helps anyone.......running 'mobile' definitely seems to be the easiest solution to it all. (Freezing your butt off on a hill to catch winter solstice sporadic propagation is a bit of a young mans game though! )

The things we get up to to enjoy this weird radio hobby....right?

All the best,
Victor

I borrowed a unit used in marine applications (they all run on generators) I believe the unit I've borrowed sits somewhere between the generator and the radar/hf system . At work but I'll get the brand / model no and stick it up when I get home

It's a3500w victron energy unit ,heavy bloody thing ,pity it has to go back after the weekend

Hello Victor,

Thanks for the great reply. As ever, your technical knowledge and practical skills are second to none.

I am all, but, too familiar with freezing my nether regions off, chasing skip from the dx perch. Lol.

As you say..... " The things we do for this hobby!"

73s John.