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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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19th Oct 2014, 6:44 pm | #1 |
Nonode
Join Date: Dec 2012
Location: Bocking, near Braintree, Essex, UK.
Posts: 2,068
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Signal Generator RF
Here is a nice little project for home construction I thought others might like to have a go at building, this one is my mark two version as the first one simply would not go no matter what I did. The case came from a factory that was shutting down so here are some pictures of the progress, I have included the circuit details which will not need much explanation, the veroboard that covers a hole is for a little three inch LS for a built in practice oscillator (Morse)
Regards Ken |
19th Oct 2014, 7:08 pm | #2 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,923
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Re: Signal Generator RF
Something that you might need to address later is control of the output level. Very often when aligning a radio, or fault finding, you need to start by injecting a high-level signal, then reduce to very low level as you progress. That means that the oscillator needs to be really well screened and the power cable well filtered and decoupled. Without those features, you'll radiate so much RF that it will limit the usefulness of the sig gen.
B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
19th Oct 2014, 11:50 pm | #3 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: Signal Generator RF
An attenuator which 'tells the truth' over the required freq. and voltage-level ranges, and adequate screening, are probably THE two biggest challenges in the design and build of any signal generator. Moreover, as the freq. goes up, the problems also rise - and usually disproportionally. (Double the freq., quadruple the problems - or something like that. )
And it's those two factors (attenuators and screening) that significantly contribute to the cost of lab. type sig. gens. Al. |
20th Oct 2014, 3:18 pm | #4 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,060
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Re: Signal Generator RF
May I put that PDF document on http://www.vintage-radio.info/ please? It could be of interest to others.
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7th Nov 2014, 2:32 pm | #5 |
Nonode
Join Date: Dec 2012
Location: Bocking, near Braintree, Essex, UK.
Posts: 2,068
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Re: Signal Generator RF
Hi Paul, yes of course by all means put the PDF of the circuit on your site, in fact anyone can copy it as far as I am concerned.
There are a couple more pictures that members might like to see so here they are, and it completes the project.. Regards Ken |
7th Nov 2014, 3:48 pm | #6 |
Nonode
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,571
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Re: Signal Generator RF
This looks like the same circuit as the one in this thread
https://www.vintage-radio.net/forum/...ad.php?t=27184 There's also another version using the now unobtainable Denco coils. Keith |
11th Nov 2014, 5:49 pm | #8 | |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,498
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Re: Signal Generator RF
Quote:
To make a reliable attenuator over a wide range usually requires some machining facility to isolate the switch sections and resistors. One of the best examples I have seen being the Marconi TF801 (I think!) VHF/UHF gen. Les. |
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