Soviet East German Radio

[pwdrive]

Yes, but surely regarding the Saalburg we can help him if needs be with circuit descriptions, it's not much different to a UK receiver, it's just that the schematic layout might be a bit...Errr....different from what we might be used to.

For learners It's recognising the circuit chunks and what to expect in and out of them that's initially important to grasp.

Lawrence.

[Nowhere-Man]

No need to panic. Anyt problems with this I will detect. The more you go over something, then you find the questions. At the moment it's the modulation index I am scrutinizing. The example itself is simple. If there's a maximum carrier frequency deviation of 3000 cycles yet the modulating frequency is 1000, the index is 3. Mathematically you can use the index to calculate the carrier deviation. I tried to convert the books frequencies into megacycles to get carrier 29.5 Meg, modulating frequency 2000 Kilocycles and 29.506 (6000 K deviation quoted + cycle. So if I have got this right the modulating index is 3 because 2000 into 6000 goes 3 times.
I still have an issue with the modulation index. There is a graph that shows the indexes in fractions.
This may take a few days...

[Nowhere-Man]

P.S look on these as nocturnal tweets. Very late is when I think more clearly.

[Nowhere-Man]

I had a look at some online references but some of these stray much more into physics. Also Lawrence has filled in the gaps so just need a bit of time for it to sink in. I mean, this FM and PM venture is just days old. It's almost 3 am so time to switch off.

[Terry]

Our patience is not limitless.

Please humour us by explaining why you would need to understand what the modulation index is in order to repair a radio?

If you wish to design a completely new transmission system from scratch, that is a little bit beyond the scope of this forum, I fear ...

[Nowhere-Man]

There are some 8 pages in total. I start from the first pages but try to understand as much as possible before carrying on. Graduated steps. The end bit will give me a basic but small schematic. Once that is understood, it can be used to better clarify the Saalburg schematic. I'd been meaning to address FM for some time but tended to put it off. Then once I got to the variometers and IF circuit, I though the truth is the background here is lacking. So I crammed the information and practised a bit of maths too. I used to have dyscalcula issues so I deliberatly hit the maths to try and knock out the cobwebs.

[pwdrive]

The variable inductor tuning in VHF tuners is usually known as permeability tuning, if that helps.

Lawrence.

[Nowhere-Man]

It helps. I have all I need in the posts you typed earlier and much appreciated, thanks. In fact I always find your posts helpful.
A book such as ARRL I think is middle level technical. You don't find formulae or calculus. Just maths and square roots and ratios. It's now my favourite reference book but maybe not many people use it as it's Americanised, and geared to HAM. It's very big on graphs and I like the way they throw in a couple of questions to consolidate each point. The FM section is pretty thorough for a book that age but some points needed padding out a bit.

[pwdrive]

I used to have some ARRL books, always preferred them to the RSGB ones, maths is not my best subject but I manage, plenty of online calculators these days which makes things a lot easier.

Ref the Saalburg, have you figured out why a tapped primary audio output transformer is used yet, that system is used in many valved receivers.

Lawrence.

[Murphyv310]

Hi.
I've been is bed the last week with the real flu yes not the man variety. I've been on the car forums and at least my brain isn't to befuddled but coming back here and reading the posts has given me a pounding headache.
My feeling is simple....... NWM you are going round this the wrong way, you need to learn to walk before you run and you are learning electronics backwards, please learn from those that have been involved with electronics all their lives from designers to service engineers, come off your pedestal be honest and accept the help from those here that are giving up their time to help. Many have wives and kids and other things to do............. so please listen to the advice, it's unfair to those helping if you dont follow the correct way they do things...... which simply IS the right way!!!!!