WA Radio Scanner Users' Group

OK so there's a thread for people thinking of or having done a Foundation course, and now it's time for a thread for people considering or doing a Standard level course.

Tonight, the Ham College Standard class of 2009 commenced. Eight students have started the course - two of them WARSUG members First up was some brain-bending regs and maths. What a way to start, on a very warm night

OK here's a couple of questions in an exam for someone to answer for me

Question 3.1415926

The bias used in this amplifier circuit is
A) fixed bias
B) grid leak bias
C) cathode bias
D) combination bias

Question X

Which of the following statements is incorrect in relation to a full wave bridge rectifier circuit

A) It's transformer does not require a centre tap
B) The circuit requires two diodes
C) All diodes conduct at the same time
D) The output ripple frequency is 100 Hz

No circuits to go with the questions

Errrrrrrrrr

We're up to resistors in series and parallel

Zebedee wrote:We're up to resistors in series and parallel

And frankly my head is hurting already!

robbage wrote:OK here's a couple of questions in an exam for someone to answer for me



Which of the following statements is incorrect in relation to a full wave bridge rectifier circuit

A) It's transformer does not require a centre tap
B) The circuit requires two diodes
C) All diodes conduct at the same time
D) The output ripple frequency is 100 Hz

A bridge rectifier requires 4 diodes.

ooo I haven't done resistors in series or parallel for ages...well since I left school...

Nick wrote:No circuits to go with the questions

Yeah, that's how the question was presented to me

VK6ZMS wrote:A bridge rectifier requires 4 diodes.

That's what I thought too.. also only two diodes conduct at any point in time, no?

You can attain full wave rectification with two diodes and a centre tapped transformer as well

Nick wrote:You can attain full wave rectification with two diodes and a centre tapped transformer as well

True - but the question specifically referred to a bridge rectifier, which makes a centre-tapped transformer no good - as far as I understand it anyway.

Had the question said "which of the following is correct" then answer A would be the one they are looking for I believe... As B is false - a bridge rectifier uses four diodes. C is false, as only two diodes conduct at any one time. And D is false, as the ripple frequency would be twice the input frequency, not always 100Hz.

So, I'd say that it was a misprint in the question, that's my best guess.

Correct. It is all about taking the time to read not flick through the questions like I did.The first question needs a schematic to refer to to give an answer to.

It might be a bug in the website where the questions were. All I know is I need to do a lot more reading on transmitters and receivers. And propagation.

robbage wrote:All I know is I need to do a lot more reading on transmitters and receivers. And propagation.

Oh???

What are we up to?

For propogation (HF) try here:
http://www.ips.gov.au/HF_Systems.
It has a host of information and can be useful also if you wish to find info like what frequency to use at a particular time to travel any distance world wide...

Zebedee wrote:

robbage wrote:All I know is I need to do a lot more reading on transmitters and receivers. And propagation.

Oh???

What are we up to?

I booked in for the exam in late March [-o<