Westminster CTA5350

[ViragoRider]

I have replaced R5 and R15 and the voltages have increased. HT supply is now sitting at around 190v and V3 Anode is now at 98v and I can now hear feint stations on MW.

I have gone as far as I want to with regard to changing components and I think the set could use an alignment but I don't have a procedure for aligning this set. Is there a generic alignment procedure that I could do to see if it will improve reception? I get background hiss on all stations including Radio 4 on LW, which is the strongest station the set can see at the moment. SW has a rapid popping sound when off station which never completely goes away and MW stations are very feint.
Pat

[cathoderay57]

Hi Pat, the rapid popping noise on SW is maybe just local interference from LED power supplies etc. You might be able to improve SW reception using a long wire aerial outside the house. For MW the first thing to do is to work out if the stations you can receive are at the right point on the dial. Suggest R5 Live might be best on 909kHz (330m) or 693kHz (433m). If the dial position is correct then you can leave the oscillator alone and only the MW mixer coils and trimmers might need adjusting. Next step is to identify these and find out whether the tuning slugs are in good enough condition to be tweaked or whether they are sealed with wax. Some photos would help. Cheers, Jerry

[cathoderay57]

In your earlier posts it sounds like you are only using a short length of wire as an aerial. That is never going to give you decent reception with this set so try a better aerial before you start tweaking any trimmers. Also give the wavechange switch contacts a good squirt of switch cleaner and exercise the switch. If that doesn't improve things on MW then also check the continuity of the MW aerial/mixer coils, and the soldered connections to the wavechange switch. Jerry

[Gabe001]

I get popping on SW too, and bursts of hiss
That's local interference as Jerry said, nothing to worry about.

I don't know whether it's relevant but the 2 MW stations I receive (talksport and BBC) seem to be "weaker" recently than I remember, and I've been having difficulty receiving them on various sets using a short aerial indoors.

What I'm trying to say is that this may be as good as it gets with the aerial you're using. Many people use small Medium Wave transmitters called minimods to stream their own music and that should be received loud and clear even with a short aerial length. Alternatively use the gram input and your phone or a small external Bluetooth receiver.

[ViragoRider]

I've rigged up a "T" aerial outside the house using some speaker wire. The arms of the T are about 10 feet in length each side. It's all I can work with unfortunately. It hasn't really improved reception a great deal so it could be that I'm in a dead spot, although other radios I have seem to receive better than the Westminster.

I have attached a couple of photos for reference. The first photo shows the "coil pack" which is slightly different in design to the one in Jerry's photo of his set and is perhaps a design revision.

In the second photo, I have ringed a 4k7 resistor which is attached between the aerial input and ground. I can't find this resistor in the schematic and the only 4k7 resistor listed is the 2W one that I replaced, also seen in the picture above the one I have ringed. There is also a capacitor connected between the aerial and the coil pack which is not on the schematic. I bypassed this with a jumper wire and it seemed to have no effect on the received signal.

The slugs in the coil pack are wax sealed and today I am struggling to receive on MW. I think I'll try tonight as the reception improves slightly after dark.

[Station X]

These sets have a foil type aerial stuck to the back cover. There's a wire running from it to a 1/8" diameter banana plug which you plug into the aerial socket. THIS AERIAL IS USELESS.

With my sets I use a 60 foot long wire aerial and it works well on all bands. Even back in the 1960's, when my parents had one of these sets, a long wire aerial was needed.

As I said these sets perform well and I can receive many MW stations loud and clear at my location.

[cathoderay57]

I would check the continuity of the MW aerial coil (primary and secondary). The position of this within the coil pack is shown in the diagram against the circuit. If continuity is OK then tune to the short wavelength (190-200m) end of the MW band (with no station tuned in) and carefully adjust the MW aerial trimmer capacitor; this is the brass metal screw situated on top of the small porcelain square (not the slug inside the coil). Do not overtighten it because you could crack the porcelain. Slowly adjust the screw anticlockwise then clockwise to reach the position that gives maximum background noise. The wax sealant should separate easily and after you've finished tweaking you can reseal it by holding the tip of a soldering iron close by. The tuning slug inside the coil is likely to be much more reluctant to release from the wax and you'll risk damage if you try to turn it or melt it. If you get increased signal and noise by adjusting the trimmer alone then it's time to call it quits. There are ways of releasing the coil tuning slug if you absolutely need to, but it's better to leave it alone if poss. J

[ViragoRider]

I adjusted the MW aerial trimmer capacitor and it woke MW up a fair amount. I can now hear a few stations. I'm calling this set finished now as I don't want to run the risk of breaking any of the tuning slugs. I'm going to use this set primarily for it's SW capability and won't be using it on MW. Thank you all for your help and guidance in getting this radio working. Pat