Tuning and aerial advice

[melliesmanor]

Now that my 1930's valve radio is working some tuning advice.

It has a 4 metre wire aerial and can pick up a lot on both SW bands, MW and LW. However 198 LW is not too good (test match special!). In fact LW in general has the least 'noise'. Do you have any advice? is it orientation? type of aerial or something else?

Thanks

John

[stevehertz]

I'm not an aerial expert, in fact I come on here for info myself, but what I do know is that for long waves you need a longer aerial. Here's some tips:
http://www.staff.science.uu.nl/~tel0...es/Antenna.htm

[Herald1360]

Long Wave will seem less "lively". Although it covers a lot of metres, it isn't very wide in frequency terms- even if it were to be full it would only hold about 15 stations but in fact there are only about three that you would normally be able to hear in the UK.

A longer higher aerial would probably help, though it's possible that your set alignment may not be too clever on LW.

SW can seem very lively on a relatively simple set, but a lot of what appears to be there may well be spurious images of actual stations caused by lack of selectivity in the front end tuned circuit(s). This problem gets worse the lower the IF is.

[paulsherwin]

LW does need a long aerial for good reception. This wasn't a problem when these radios were new, as almost everybody had big 30' aerials strung across their gardens, but it certainly causes difficulties today.

Tuned frame and ferrite rod aerials work well at LW frequencies, so it may be worth building one of those in an external box.

[melliesmanor]

Thank you all. Just one more, if i may. Is a standard bit of insulated wire good enough? Thick or thin? solid or whatever the oposite of solid is lots of thin wires i suppose.

Thank you.

John

[Herald1360]

Ordinary insulated wire is fine, stranded is probably more resilient to flexing in the wind. Something like 16/0.2 PVC insulated will be fine (same size as inner core of 3A lighting flex) or even bell wire. Don't pull it too tight between supports and ideally use a short length of polyprop rope or similar to support each end though you'll probably get away with just looping the wire round the eyescrews or whatever fixings you use. Drainpipe, gutter bracket, fencepost, tree or WHY.

Ideally bring the end into the house via a dedicated hole in the wall- angled upwards from outside to inside and leave a drip loop with the bottom below the point of entry to keep rain out. Sealing the outside end with silicone sealant is good. Or just run it in via the corner of an opening window- the wire will be thin enough to bend round the frame etc.

How to do a vintage job:

http://www.northcountryradio.com/Art...%20Antenna.htm

[paulsherwin]

If you are doing something indoors or in a loft, any copper wire will be fine, so just use the cheapest stuff you can find. There is a lot of wire in a scrap transformer.

For an outdoor aerial you can build something that a radio amateur would use, but there are lots of alternatives. If your garden uses a chain link or chicken wire fence you may be able to use that, or if you have a wooden fence you can run a wire along it. If you have a long garden washing line you can replace it with steel cored washing line and use that as an aerial. You're only limited by your imagination.

A good earth will help too. Try using your central heating piping.

[clay shooter]

I have often wonderd if it is possible to use redundent telephone wires as a long wire ,
I bet there is a telecoms engineer out there who can advise on the subject

[AC/HL]

If you're sure it's redundant, BT take a dim view of interfering with their plant.
https://www.vintage-radio.net/forum/...d.php?t=107308

[crackle]

Originally Posted by paulsherwin

A good earth will help too. Try using your central heating piping.

Won't the central heating piping be at Mains earth potential, due to the now common practice of bonding.

Mike

[chipp1968]

In this house the Earth comes in from the earth pole buried just outside the house.
The electric earth goes to this as well, but I get better results connecting the radio earth to a wire coming from outside than I do with connecting it to earthed pipe etc inside.
I definitely need an earth connection here as it dramatically reduces the interference. It's still there but it goes much quieter with the earth.

[clay shooter]

Back to the redundant telephone wires, the one to my house that hasn't been used since we went fibre optic years ago, has its own earth rod and I suppose a lot of the older properties have the same. Would these be of use ?

[Junk Box Nick]

A simple trick I used to use for improving medium wave using an indoor aerial was to hang a vertical length of wire from the curtain rail with a coil at the base which consisted of a lot of copper wire wrapped around a ferrite rod and the other side of the coil plugged into the aerial socket.

Don't ask me how much 'a lot' was as I have long forgotten the detail - it was always a crude arrangement - so a bit of experimentation will be required, especially for long wave as you will need a bigger coil than for medium wave.

[AC/HL]

The earth almost certainly won't be in use. It was probably a shared service line, which I don't think are used since the end of post-war austerity.
If it is still functional it could be useful.

[jsbhavsar]

We in India do the "copper mesh aerial" setup for MW & SW. We do not have LW here.

It is hundred of meters of fine uninsulated copper wire strand woven in a mesh hung between two plastic insulators. You just plug a insulated flexible wire from the mesh to the radio's aerial socket.

I use a thick single conductor copper wire 1/16 or 1/14 uninsulated copper wire between two egg insulators on the topmost portion of my building. I then run a insulated 1/18 wire from that copper wire to the aerial socket.

[G8HQP Dave]

That is a capacitive hat. The wire connecting it to the radio is the actual antenna.

[jsbhavsar]

Capacitative hat? Its a new 'term' I read hence would like to know more about it.

My Dad used this mesh aerial for all the 25 yrs he used his Philips Valve. Initially this copper mesh aerial was deployed atop however with pigeons and birds creating trouble it was brought indoors. I grew up seeing this structure daily, though the pictures posted in my previous are not mine.

Do you mean to say that the "copper mesh" is acting as capacitative hat?

[G8HQP Dave]

Yes. Adding capacitance to the far end of a short antenna does not mean more signal is picked up, but it reduces the antenna impedance so more signal is developed across the receiver input.