Page Four


Even so,it wasn't much to look at, but at least it WAS a raster.

I eventually twigged that the tube wasn't cut off as a fault... the Brightness was simply turned down!


At this time, EHT weighed in at 8Kv. Later on, tweaks and a steadily de-gassing tube improved this to 10Kv.


As for getting some sort of picture, I'd need a suitable signal.

From the Tuning Indicator, it looked like this would have to be a Channel 4 or 5 signal.


This is what I saw on Channel 4. Hopelessly out of alignment though, both picture-wise and tuning-wise.


Always a good idea with these Bushes is to take out the two subsidiary user tuning cores and inspect them for condition.

Here, I'm removing the one in the middle. This tunes the anode side of the first RF stage.

The one to the left of this tunes the grid side of the first stage, at the aerial input, and only has a broad effect.

The spring-loaded button to the right - the 'main' one with the scale - adjusts the local oscillator frequency. It is supposed to be set to give maximum sound. If the rest of the alignment is correct, this should automatically also provide the best picture.


Well what do you know.. The check was worth it. The left hand core is mostly missing.


I wonder if the rest of the core is still inside the coil?

Let's have a poke through with the screwdriver.

Nope... it comes straight out the other end without any sign of core.


What a shame I have now given all my spare TV22 chasses away... might have yielded a core.

Never mind. I make one out of a piece of another core, stuck to the old one with epoxy and all wrapped up with paper tape.

It doesn't look the business, but it works! I can now re-tune all the adjustments to Channel 1.


Want to see the picture? Wait a little longer. Here is a 'dogbone' resistor which measures only slightly low but looks generally distressed. It feeds the screen grid of the line output valve, the part of which also doubles as the line oscillator. It is replaced.

Talking of the line stage, the 'line drive' level also has to be set up on this circuit. This is duly done.


I have to say I'm not hugely impressed with the picture on the screen. It is exhibiting a deficiency in the LF video response, as evidenced by smearing on the 'letterbox' on the Test Card.

This is bad news. Nothing in the video amplifier seems to be causing it. I am reluctant to consider a full IF realignment... thinking of stuck and broken cores etc. It was all very well in 1953, but now...

So I do something really naughty as a temporary solution. I solder in a short piece of lead to the final IF stage anode, to provide some capacitance to alter its tuning.

You can see this taped to the upper side of the chassis.



While this has a beneficial effect, it is clearly a bodge that'll have to be put right later.

After ten hours (so far) of 'burning in', the picture is still steadily improving.

Another remaining fault is a tendency of the frame to bounce at some positions of the height and linearity controls. I'll be looking into this next.

Then maybe to try fitting the Mullard tube out of my Baird Townsman, if it proves practicable, to compare it with this one.


The frame bounce was cured by changing this ECL80 frame valve... twice.

The first replacement I tried also proved faulty. These ECL80s are not the best of valves in my experience.


The Bush chassis - to top - now meets the Baird chassis it will replace.

Somehow I'm going to have to mount the Bush in the Baird cabinet. The main mass of this cabinet is not seen here.



I had previously fitted a non-standard Mullard tube to the Baird and I had high hopes for this.

However the tester showed it had an intermittent partial short on the heater, so that's another rare early round tube that will have to be scrapped.



Here's an old treasure found in the bowels of the Baird that I intend to re-use. It's a valve audio amplifier complete with bass and treble tone controls.


Two changes on the Bush chassis are needed to accommodate this.

On the left, a 3 ohm power resistor replaces the connection to the Bush's original speaker. On the right we see the new sound output socket. This is connected into the volume control.

The amp uses a Belling-Lee 'aerial' socket for the audio input, so I have stuck to the same convention. This will allow the convenience of using a simple aerial lead to connect up.