Active Ferrite Aerial Project

[Geaney]

As mentioned in David's post about EPE magazine projects I decided to make a start on this before I headed off of my little road trip.

At this stage I've built the ferrite loop section and it's ready for a housing which will get done in due course. The project calls for seven rods but I bought a set of ten and nine fit in the tube so nine are in use. Also, they are longer than the ones suggested. For the secondary loop the recommended number of turns is 29 to give an inductance of 160uH. Since I'm using more ferrite I had to reduce the number of turns to 26 to get close to 160 - mine reads 170uH. I figure that's close enough.

I've got the base more or less ready for wiring. I'm using components available on hand so it doesn't necessarily look pretty at this stage. Cosmetics will come later if the thing works.

So, at this stage it's ready to have the little circuit board prepared. I got back from my road trip earlier this evening and on checking my mailbox discovered something very wonderful - more about that in the next post.

Cheers, John

[Refugee]

wow that is a posh coil former with the gold bar code on it
Is it going to have a simple gain stage or will it also be tuned as well?
I have been thinking about something I can mount in a loft for some time.
It will need a rotate facility by the looks of what I can see right now.

[Radio Fixer]

Looking interesting John

Gary

[pwdrive]

You could loosely couple the wire antenna to the tuned circuit as a switched option.

Lawrence.

[Geaney]

Had a bit of a hiccup with the rotary wafer switch. Obviously it's one of China's best and the minute I touched the soldering iron to the first pin it melted the surrounding plastic and fell into the switch body jamming the whole thing up. So I've ordered up something that hopefully will be a bit more robust.

Apart from that it's coming along. I'll get started on the turret while I'm waiting for the new switch.

Cheers, John

[Old Sparky]

I've had problems with those plastic bodied rotary switches, too. As you say, John, it doesn't seem to take much heat to melt them. Sometimes Vintage Parts.com has the old fashioned metal bodied rotary switches with paxoloin (or should I say SRBP!) wafers. Much better! (NB the URRL for Vintage Parts.com is 'markhindes-easywebstore.com' or something similar. There is a link to it over on UK Vintagre Radio Repair & discussion Forum.

[Skywave]

For a rotary switch that is handling R.F. currents, ideally, you need a switch with ceramic wafers. But from where such items are available these days, I regret to say that I have no idea! Faced with a similar problem of R.F. switching in the past, I used miniature co-ax relays.

Al.

[Radio Fixer]

If the tags are long enough its a good idea to hang a small pair of forceps below where you are soldering. Right down against the plastic case but still tin the wire first, hook through and solder very quick.

Forceps are very useful and over the years I have acquired several different sizes and shapes.

Gary

[Geaney]

New (sturdy) wafer switch arrived today so it's wired in and that completes the wiring up of the base unit. I did a quick power up and current consumption is about right and nothing went puff!

I started on the aerial unit this afternoon. That's pretty much done so now I just need to build the turret to put it in. With luck I'll get stuck into that tomorrow.

Cheers, John

[Geaney]

Turret is coming along - no marks for cosmetics at this stage. Need to rig up the 'dial cord' for the tilt mechanism and decide on how the turret will run on the base unit. Hopefully I'll get that done tomorrow.

Incidentally, some of you may have noticed that I did not feature anything about etching the pcb for this project. There's a very good reason for that! While I was on my holiday travels one of the members of this great community went and etched a board for me. When I got back I found the etched board plus the two main semiconductors in a jiffy bag in my mailbox. Points (pints?) for anyone who guesses who the benefactor is. Obviously one member is disqualified as their pints are already secured

Since I got started in vintage radios, the best thing I did was find this community!

With any luck I might get to test this project out by the weekend.

Cheers, John