Avo RF Signal Generator HF 134

[AlanBeckett]

This, on the other hand is a bit silly - http://www.ebay.co.uk/itm/Advance-Electr...uipment_ET&hash=item43c6d5e7b6

It might be worth it if it was just round the corner. Generally the old Advances are very well sealed up, as they should be, so external appearance, within reason, is of little consequence.

Alan

[Yorkie]

That Avo 'Wide Range Signal Generator' was a gift at £12.50 - the valves inside it are worth that! The full manual is on the forum here:

http://golbornevintageradio.co.uk/forum/...p?tid=2773&highlight=AVO+Wide+Range+Signal+Generator

They often come minus the output probe but one is easily made in a small can from the values of components shown on the circuit (200pF & 400pF caps, a 400 Ohm resistor and a 20uH choke).

As to the TECH TE20D, it's a more modern piece of kit (1970s on) - I've owned two of them and I had a not very good copy of the manual - the only one to be found on t'internet, so I cleaned it up and posted it on this forum (or rather Joe did!). It can be found here:

http://golbornevintageradio.co.uk/forum/...p?aid=9581

TE20Ds sometimes fetch quite high prices - other times not so, as with the AVO. Well worth £25.00. The one at the listing looks in very good condition.

[tim.54]

Drat ,just got in from work and missed the first one! have got my eye on the TE-20D ,looks to be in good condition , will let you know how i get on.
regards, tim

[Skywave]

Seriously, it all depends on what you want to do with it and what you expect from it by way of accuracy, purity and facilities.
Alan

That is a good set of criteria to determine what to buy - along with what you want to use it for - and how deep your pocket is. I'll expand on that: depending on what you want to use it for, the following factors are relevant.

1. Accuracy & resolution of frequency indication.
2. Purity of waveform and freq. stability.
3. Frequency range.
4. Modulation facilities.
5. Range of the attenuator (dB), its accuracy & its resolution.

Of those, 1,2 and 3 don't really require any comment: it is almost sufficient to say "the more & the bigger, the better".
4. In addition to A.M., #4 includes the ability for F.M. and if it will handle an external input signal that will sweep the frequency over a substantial range - say, adequate sweep for nominal 465 kHz and 10.7 MHz IFs.
5. This is probably one of the most difficult specs. for any manufacturer to achieve, especially if an output down to the µV level is required. The main reason for that is screening: substantial screening and filtering. It can be very difficult at high frequencies to avoid a substantial part of the signal that is entering the attenuator to by-pass that attenuator and arrive at the output socket. It can also be difficult to arrange matters so that the output impedance of that attenuator remains substantially constant over the freq. range of the generator - especially if that freq. range is a substantial one.

In conclusion, they are the main reasons why lab. standard sig. gens. are so expensive. But as I said, it depends what you want to use your sig. gen. for. For example, if you wish to use it for reliable, repeatable and meaningful sensitivity tests on comms.-type radios and measure S/N ratios, then a lab. standard sig. gen. is required. However, for most domestic radio service, a basic (and much cheaper) type of sig. gen. will be perfectly adequate.

On a general note, when it comes to buying any item of test gear, by using the adage "buy the best (= most expensive) that you can afford", you usually won't go far wrong.

Al. / March 13, 2014 //

[AlanBeckett]

On a general note, when it comes to buying any item of test gear, by using the adage "buy the best (= most expensive) that you can afford", you usually won't go far wrong.

Along with a bit of research I would suggest. I've seen quite basic ones advertised for quite fanciful prices.

Alan

[Yorkie]

Out of curiosity I've been watching this Advance 'E2' described as in 'GWO' with a starting price of £29.99. The auction closed late last night - no bids, so it's been re-listed - again with a starting price of £29.99. Well worth a punt. (Dare I say that the three valves and mains transformer are worth that alone?). They're well made and though externally they're often a little weathered cosmetically, they're immaculate inside. Well worth a punt, it seems to me:

http://www.ebay.co.uk/itm/Advance-Electr...4897.l4276

Covers 100KHz - 100 MHz in six bands, claimed accuracy 1%. (Int/Ext modulation, attenuator etc). The manual can be downloaded FOC from Jon's site here:

http://www.thevalvepage.com/download/dow...dva_e2.pdf&dir=advance

[Joe]

The manual can be downloaded FOC from Jon's site here:

http://www.thevalvepage.com/download/dow...dva_e2.pdf&dir=advance

Or our Archive.

- Joe

[tim.54]

Thanks for everyones help , i`ve bought the Tech TE-20D ,(looks to be in good condition , have yet to download the manual . last Sunday i collected a Bush vhf 81 ,(already have a couple but this one i`m doing up for my mother in law )from a bloke in Heysham (won on e bay ) £10 (it works but has the usual blown mains cap ! etc )he also threw in a Hacker Helmsmann (a bit tatty but still interesting , was wondering as heysham is a port ifit was possibly used on a boat ?) for nowt . we had a look round Morecambe and there is an antique shop on the front , i came out with a Avo meter 8 MK 5 in superb condition with leather case and leads ! with manual and original guarantee card. (the 15v battery needs changing , does anyone know of a supplier ?)
Regards, tim.

[Joe]

e-Bay or The Small Battery Company, if you've got deep pockets.

I made my own: http://golbornevintageradio.co.uk/forum/...p?tid=1317

- Joe

[tiv48]

Tim 53
I still have some of these batteries if you would like one let me know they are NOS but 4 years old
Rob T