- Thread starter Guineafowl
- Start date
ajlelectronics
Member
- Messages
- 10,555
- Location
- Gloucester, England
Bear in mind that I have been doing it professionally since 1986 and things that I might do at home would often not be sensible to do in a customer's home.
Ross365
Member
- Messages
- 1,961
- Location
- UK
Re silicone grease, my understanding is that silicone should be totally avoided on electrical connections, whereas... Vaseline is fine. I must admit I don't quite understand the fine points as to why that is, but it's a practice I've adhered to for a long time and been happy to do so.
I've been flexible on aerials and antennas for the last 60 years, but in view of "modern-day Washington", aerials is to be mandatory!
I've been flexible on aerials and antennas for the last 60 years, but in view of "modern-day Washington", aerials is to be mandatory!
Onoff
In the land of the unfinished project I am King!
- Messages
- 12,428
- Location
- Sevenoaks, UK
I use on aerial connections, to pack limit switches, on crimps etc. Stuff stays like new.
George A2Y
Member
- Messages
- 109
- Location
- Highlands
If the existing route proves a no-go it may be worth checking the wall thickness below the window as sometimes croft houses have thin walls under windows even if the original inset has been framed flush with the walls to provide a deep cill. If there is a socket or other access it's worth a look, failing that you could make a very small hole in the plasterboard/ insulation and poke around with a coat hanger type wire to see if there is a significant void. Our croft house has about 600mm of stone in the main walls but only about 200 - 250mm below the windows.
Guineafowl
Member
- Messages
- 1,211
- Location
- Nairn
Yes, I used it all over my boat and the connections kept like new. Use it all over car stuff now as well.
I know what you mean. Our last croft-type house was as you describe, but I filled them in with studding, to make a decent-sized windowsill, anticipating it would used for storage of lots of crap, which it was, and a cat lookout point , which it also was.
Farside
Badly Welded Man
- Messages
- 6,127
- Location
- Ireland
Nah, they just shifted it down a bit.
I scored two of the old stock aerials of the upper group and have been using them as diversity antennae on 4G for the past few years.
Kayos
Gone......
- Messages
- 9,422
- Location
- Yorkshire
Metre long SDS, even if you have to hire the drill will see that done in minutes
Ross365
Member
- Messages
- 1,961
- Location
- UK
Re silicone grease, there are clearly lots of people who use the stuff liberally, but there are some issues with it as described here; https://support.newgatesimms.com/not-recommended-silicone-grease-use-on-electrical-connectors/.
Vaseline is generally just as good but without the problems of silicone, which include (but not limited to);
>silicone is hard to wash off anything that it comes in contact with (needs a chloro solvent); you wouldn't want to get it on your glasses
>silicone creeps, i.e. it slowly migrates along surfaces
>where sparking occurs, silicones can form hard solid silica, which is a really good insulator.
When I worked in chemistry (long ago), we used huge amounts of silicone grease every day to ensure ground glass joints did not leak or seize, but I never use it near anything electrical.
Vaseline is generally just as good but without the problems of silicone, which include (but not limited to);
>silicone is hard to wash off anything that it comes in contact with (needs a chloro solvent); you wouldn't want to get it on your glasses
>silicone creeps, i.e. it slowly migrates along surfaces
>where sparking occurs, silicones can form hard solid silica, which is a really good insulator.
When I worked in chemistry (long ago), we used huge amounts of silicone grease every day to ensure ground glass joints did not leak or seize, but I never use it near anything electrical.
Guineafowl
Member
- Messages
- 1,211
- Location
- Nairn
Out of interest, I asked about the wiggly track balun on Physics Forums. I find that several sources are often best when seeking an explanantion.
How does this antenna balun work?
It’s this type, commonly fitted to UHF Yagis for TV signals: Online searches, including a reverse image one of the above, haven’t returned any accounts of how it’s designed. A folded dipole in a Yagi setup apparently has an impedance of 10-40 ohm. The signal must pass to 75 ohm coax. So there...
Main points:
- The impedance of the folded dipole (300 ohm) is apparently not greatly affected by the passive elements, when spaced well apart as in a DTV aerial.
- The wiggly track is a half-wavelength transmission line, which results in the +V and -V at the dipole terminals becoming 2V at the connection to the coax centre. The doubled voltage reduces the impedance to 1/4 (300 -> 75) since impedance is proportional to the square of the voltage, keeping power constant (as in, P=V^2/Z, hence Z is proportional to V^2).
- The balanced +V -> earth <-V at the dipole terminals becoming 2V -> earth at the coax centre also achieves the bal -> un transition.
Forget The Coax, Wire Up Your Antennas With Cat 6 Cable
These days, anything with copper in it is expensive. If you doubt that, a walk into any Home Depot electrical department, where the wire is locked up tighter than Fort Knox, will prove otherwise. C…
hackaday.com
Will this help??
ajlelectronics
Member
- Messages
- 10,555
- Location
- Gloucester, England
Forget The Coax, Wire Up Your Antennas With Cat 6 Cable
These days, anything with copper in it is expensive. If you doubt that, a walk into any Home Depot electrical department, where the wire is locked up tighter than Fort Knox, will prove otherwise. C…
Will this help??
Only if you are a masochist. That is in the realm of climbing Everest purely because it's there, rather than for any practical reason. The twisted pair will require Baluns each end as well as impedance transformation to 75R. On top of that, unshielded twisted pair will be susceptible to pulse interference, shielded twisted pair less so, but why create problems when there is a perfect and freely available solution off the shelf?
