Fault finding and likely faults in the if stages

There are many reasons why you may get little or no stations on a radio. Once again the WAXY CAPACITORS are a source of problems,its best to change them all on spec.

As mentioned before the METALLISED COATING on the outside of valves tends to flake off and frequently causes what they call self oscillation which is a sort of instability within the valve,the metallised coating acts as a screen. The valve itself is usually ok and rather than just buy another one,my cure is to wrap tin foil around the glass envelope then wrap fine fuse wire a couple of times around the bottom of the glass envelope then soldering a blob to the wire and soldering this to the correct pin on the valve. This should effect a good cure. And save you money!

Another major cause of poor reception is POOR ALIGNMENT OF THE IF TRANSFORMERS,usually because somebody has"twiddled" with them. To set these up properly you need a non metal trimming tool,a signal generator and preferably a circuit diagram.i will deal with alignment on a seperate page.

Yet another cause can be the IF TRANSFORMER CORES NOT PEAKING when you try to align them with a signal generator. I have found that the SMALL LOW CAPACITY MICA CAPACITORS within the metal can,often tend to "drift" capacity causing a sort of "unpredictable I.F. effect". Changing these is not an easy job,they are usually inaccessible,you have to remove the metal can,and to get at the screws can be and often is...a nightmare,they are usually buried under piles of wires or in the case of Bush radios...paxolin boards. Its best to draw the pin connections on a bit of paper to assist your memory as well. Another cause of non peaking also can be a BROKEN IF CORE,i have had them where they have snapped inside the core housing and the act of turning the radio upside down makes the broken core slide up and down inside the core housing. The cure here is to unscrew the top half and turn the radio upside down and push the bottom half out. Sometimes though its not as easy as this and you will have to remove the entire i.f. can. When you have the two pieces simply superglue the two pieces together wait until they both are firmly bonded and put it back into the if transformer....magic. You will obviously have to realign the if stages now though.

Just a note to conclude regarding the cores of if transformers,DO NOT ATTEMPT TO ALIGN THESE WITH A METAL SCREWDRIVER FOR THREE REASONS.
1.You are more likely to round the slot on the core if it is a plastic topped one.
2.Screwdrivers are metal and will give you false readings when tuning the core due to magnetic effects
3.The third and most important reason is,if the core is stiff and the core is a ferrite one it will almost certainly snap inside the core housing. To remove is a difficult job,its best to apply a little bit of heat quickly to the core..not too long though!! then turn using a plastic trimming tool. THIS TIP COULD SAVE YOU HOURS OF HEARTACHE!! i can supply these trim tools if necessary. please USE THE CONTACTS PAGE FOR MORE INFO.

Also make sure that the AERIAL you are using is a decent length. Many sets produced did not have a great deal of gain as opposed to the modern radios of today.