Advance E2 valve bases

[Dursban]

I have bought a Advance E2 and want to get it working as it should. I have been looking at the valve bases and tying to compare them to the circuit diagram. This has resulted in total confusion as extra diodes and resistors seem to have been added (see photo)

I would be very grateful if someone could post a photo of the valve bases so I can make sense of it all. Please forgive me as I am a complete amateur when it comes to vintage equipment.

[AdrianH]

Welcome to the forum
Perhaps this will help
http://www.thevalvepage.com/resource...&id=a2kpN2FoHX

That is if I have got the correct thing, not a diode in sight, perhaps someone tried to replace the valves with diodes?

Adrian

[AdrianH]

In addition if you use the search function at the top of the page you should find a feew other threads on the Advance E2 some with pictures of the inside like this one.
https://www.vintage-radio.net/forum/...d.php?p=998629

Adrian

[Jez1234]

Yep looks like someone decided solid state rectifier would be a good idea but the socket looks like 'a valve in place also! A component, probably a resistor, seems completely depleted of its original magic smoke content by the looks of things also.

[60 oldjohn]

Looks like 3 diodes on two valve bases

John.

[Silicon]

Are the square rectifiers BY234s?

I can't find any data for them. What are the other rectifiers?

Several components look like they have overheated.

I don't like soldering components directly onto the valve holder tags.

You can buy Octal valve bases that will plug into the valve holders.
Mount the rectifiers, resistors, etc on the valve bases and you will then have a removable solid state rectifier.

Use rectifiers like the UF4007 which are rated for 1000V.

[Jez1234]

It shouldn't be over difficult to just put it all back as Advance intended and then take it from there really. As well as keeping things original this avoids issues with over voltage stressing the smoothing caps etc whilst the valves warm up and start drawing current, also it's necessary to add a series resistor when going SS to compensate for the forward voltage drop of the valve rectifier. If this is not done then again there is a risk of over stressing capacitor, but also the circuitry will be operating at a higher voltage than intended which may effect linearity and calibration.

Personally I'd put it all back to original but with leaky old waxies and PIO caps replaced, resistors too where gone high in value, smoothing caps etc checked out and sorted if required, some contact cleaner worked through switches and valve bases etc then a re-calibration (assuming info available on that. Otherwise wing it with advice on here).

I have quite a regard for this era of valved Advance test gear. It is usually intelligently designed to get the very best out of the basic topology used and with a robust reliability.
Can often give 80% of what the likes of Marconi Instruments or HP had in the day (usually within a more limited, but adequate, range) for what would have been a much lower price.

[Leon Crampin]

I would suggest that the original 6X5 rectifier should be replaced with an EZ80/6V4 for reasons of reliability. Fit 5 single strand thickish wires to the relevant pins of a B9A socket, feed them through the existing octal spigot hole and solder as appropriate to the tags of the octal base. The new valve then sits just above the original.

These are good generators. Apart from the suicidal 6X5 which can cost you a mains transformer, replace also the incoming mains RF filter capacitors - they will be leaky, which can endanger other test gear.

Leon.

[60136 Alcazar]

I acquired the outwardly similar E1 in the early 1980s and must have replaced it with an Altai or something later on. I remember subsequently checking the calibration of both generators at some point and establishing that the E1 was far more precise in both frequency, calibration and waveform. I still use the E1 as a second generator when I need one for waveform and one for a marker frequency. The changes made for the E2 involved the 6X5 changing from full-wave rectifier delivering 200VDC to half-wave delivering 300VDC (with greater strain!), revised mains transformer, redesigned AF modulator and a new RF oscillator which looks like they had a struggle to get to the result they wanted..

If you need to adjust the trimmers in the coil box, then the use of a non-metallic insulated tool is necessary - there should be holes in the screening box to allow these adjustments. It looks likely from the circuit diagram that there will be some interdependence between ranges in the E2, so it is likely there is a particular order of adjustment required - typically low f to high f, but possibly the other way round. There is also a trimmer on the main tuning control which further complicates matters, since it is active on all ranges.

[Kentode]

Originally Posted by Dursban

I would be very grateful if someone could post a photo of the valve bases so I can make sense of it all. Please forgive me as I am a complete amateur when it comes to vintage equipment.

The advice given so far may be a bit beyond the OP's skill set!

On this forum in 2017, thejazzageuk had a thread titled "Advance E2 Signal Generator repair".

This has a good picture of an unadulterated E2 which may be worth studying. It can be found using the search facility at the top of the page.

Hope this helps.

[Station X]

Originally Posted by Kentode

The advice given so far may be a bit beyond the OP's skill set!

On this forum in 2017, thejazzageuk had a thread titled "Advance E2 Signal Generator repair".

This has a good picture of an unadulterated E2 which may be worth studying. It can be found using the search facility at the top of the page.

Hope this helps.

Or just click on this link:-

https://www.vintage-radio.net/forum/...d.php?t=142037

[Kentode]

Thanks Graham, I can't hyperlink with this 'phone, hence the long-winded explanation!

[Dursban]

Originally Posted by Silicon

Are the square rectifiers BY234s?

I can't find any data for them. What are the other rectifiers?

Several components look like they have overheated.

I don't like soldering components directly onto the valve holder tags.

You can buy Octal valve bases that will plug into the valve holders.
Mount the rectifiers, resistors, etc on the valve bases and you will then have a removable solid state rectifier.

Use rectifiers like the UF4007 which are rated for 1000V.

Well spotted, the square rectifiers are both BY234s.

[Dursban]

Thank you all for your comments so far.

You are correct Kentode, many of the comments ARE above my skill set!

I have removed the non standard rectifiers and resistors, with my aim to put it back to standard, but using modern components. Gaining a deeper understanding and getting the E2 working again is my priority.

I'm not sure what the previous owner has done, but a couple of the resistors on the valve bases have been ""cooked" and broke in half as I removed them.

I now move on to what might be a bigger problem. The "Supply RF choke" (L11) seems to be a little crispy....

What can this be replaced with? Does anyone know what size choke this is? Is there a modern alternative that I can use (anything available at RS Components would be very handy). Thank you in advance for your help.

[Ed_Dinning]

Hi, it looks like a fairly standard bi-filar wound supply choke of a few uH value.
There should be plenty of suitable types about, the value is not critical and is to reduce RF getting onto the mains.
Modern common mode chokes should do if of a suitable current rating and will have many more uH (not a problem) than the original

Ed

[Leon Crampin]

The chokes were probably cooked by the leaky RF filter capacitors referred to above.

Leon.