aerial in OU T527 home experiment book

[armandine2]

just started getting together my components to do the experiments in an old open university course on Radio frequency engineering (T527 / T327 no longer available) - and the first dilemma/decision is the aerial construction. The kit was not part of the course that I enrolled in, although the text indicates that this was at least the idea for students to have it - the kit would've had a ready made aerial.

I have gotten a ferrite rod and wonder if I should make Litz wire for the aerial and wind as indicated over a bit of ptfe tape.

Any thoughts?

[wasedadoc]

That looks like a Medium Wave radio. (530-1600 kHz).  Around 1965 I wound my own ferrite rod aerial.  I used gummed parcel tape (is that still available?) to make a sleeve which was a tight fit on the rod but could be moved along it if desired.  Wire was ordinary enamelled single core copper.  Single layer of touching turns.  I used sealing wax to secure the ends of the coil to the paper sleeve.  A couple of Terry clips to hold the rod.

BTW C7, 100pF looks a bit on the low side to me.  3k impedance at 530 kHz.

[TimFox]

C7 = 100 pF is the filter capacitor for the half-wave peak detector using diode D1.
A larger value might cause "failure-to-follow" distortion.

[807]

Fond memories of watching the Open University programmes in the 70's on BBC2 Saturday mornings. Most of it was way over my head in those days, but still fascinating to watch. Loved the opening fanfare.



Are those courses still available online anywhere?

Like wasedadoc, when I built my first crystal set radio, I used enamelled copper wire wound on a piece of paper wrapped around the ferrite rod. This allowed me to tweak the range I could tune to by sliding the windings along the rod. Used a "real" tuning capacitor in those days of course!

[armandine2]

I'm guessing the course isn't being taught anywhere now - it came up rarely when I searched for it online.

However, the text Electronics of Radio, covers much the same ground:

https://www.amazon.co.uk/Electronics-Radio-David-B-Rutledge/dp/0521646456

for my experiments I'm still waiting for delivery of varactor diode - and have ordered Litz wire and 44AWG to try and make my own.

Nothing happens quickly on my bench