Radio re-alignment twiddlesticks

Aluminium if you just want to be able to tweek a slug in a coil.

Or a rigid plastic.

But you can buy tuning things for coil slugs.

There are a number of uses for non-magnetic and spark-proof screwdrivers, such as for the watch and clock trade, as well as others.

They're not always cheap though.

you don't have any?....shocking

Spaghetti.

Presumably the dried kind?

We used to use plastic knitting needles. However be aware that if we are talking vintage radios etc, then some cores had hex holes all the way through, allowing the real nylon tool to pass through the nearest core and tweak the lower one and of course vice versa. This is needed to get proper band pass tuning. You need a sweep generator and a scope of course to do the alignment correctly, with proper crystal frequency markers to make sure the 3dB down points are in the right place. Of course older cores can get stuck or broken, so I wish you luck.

Brian

In the main one needs to consider why something needs to be realigned. Normally cores in coils tend not to move unless there is excessive vibration over the years, but sometimes small capacitors in or around coils can go faulty, and need replacement with new ones. Then you can realign the IF strip. Often there are band pass double coil systems to keep the audio reasonable on AM, and cores do tend to get stuck. So be extremely careful as the cores are very easy to chip or break. If its a normal AM radio, you may need to align the aerial coil and capacitors as well so the gain is reasonable over the band. Some are better than others in this regard, but make sure once you have dont the coil at the low end and the capacitor at the high end it does not have a dead spot in the middle. You can literally spend ours on changing the gain points to track it as good as you can. The oscillator often does drift a little so always test the stations near band edge are still receivable. Of cours if its an FM tuner thing can be different, the old school system was much the same as just discussed except instead of around 455Khz for the IF its likely to be 10.7Mhz and because of the way fm is detected, alignment may mean using an alternative detector to see what is going on, but apart from that the principals are the same. A lot of tuners and small portables were made using single chips, and although it may look a bit odd, often the actual circuits were very similar but ceramic filters could be used instead of coils in some places. These, assuming they are not faulty tend to be very lop sided in the way they roll off, but you need to use their frequency to align coils to try to achieve an equal roll off each side. Brian

Back in the day we used plastic knitting needles, those being a common item in many homes. Another option is a kebab skewer or cocktail stick. soak the end in superglue to stiffen it, as the actress said to the bishop.. The purpose made ones I used to have had little bronze leaves in the end of a thermoplastic rod. I also had nylon one with hex ends for some of the slugs that had hex holes

Thanks Brian. Interesting.

Bill

The ones I have aren't a very good fit for these cores and I don't feel like taking a chance on 50 year old cores. I would normally order some, but given the Xmas post and all the rest of the mess right now, I'm going to roll my own this time and go for a nice, snug, bespoke fit.

As I said, any plastic rod...and a nailfile...

Sounds like you know what you're on about here, Brian. I know there are differing philosophies when it comes to realignment. I keep a ton of high-end test equipment which comes in handy as I already have everything I need. I like to go through stage by stage with a sweep generator and examine the outputs of each with a spectrum analyser to get the 'humps' of the passband all evenly distributed around the relevant IF. People who just go through the stages peaking each core for maximum volume risk sending the thing into feedback - and ending up with such a narrow 'sweet spot' that the slightest temperature change will knock the receiver off, requiring frequent re-twiddling of the tuning knob. Worst of all are the screwdriver jockeys who leave a trail of fractured and jammed pot-cores in their wake. Grrrrr!!

I like the idea of the plastic knitting needle Brian mentioned. I think that should do the trick and I do have an emporium for haberdashery items within walking distance...

You can buy them for not much. Try EBay. Typically they are double ended with bronze blades.

I mentioned it actually.

That is a rare and valuable thing.

I generally use ebay or amazon

Very helpful as usual Mr Reay....good man

Take a month of Sundays to arrive at this time of year. Hence the original question. And this is supposed to be a DIY group!

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