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Hi and Coax Advice Please (8 replies)

M7 WFR
1 month ago
M7 WFR 1 month ago

Hi,

Let me introduce myself, I am Geoff Kirby based at West Mersea.  I have been meaning to get into ametuer radio for a while now and have finally got around to it at long last.

With the help of Essex Ham and the excellent online training hosted by Pete, I have just passed my foundation (10th May 2021) M7 WFR

I would like to to get my shack setup asap and start making contacts.  I would appreciate some coax advice please.  I want to connect a IC9700 to a Daimond 2m vertical using N connectors, I know it has to be 50ohm coax, but when I go onto websites like Nevadaradio it gives me several coax options?  This is a 6 metre run of coax from antenna to shack, so cost is not an issue, I would greatly appreciate some direction as I do not what gauge I should be looking at?

 

Geoff

Peter M0PWX (2E0PWX)
1 month ago

Hi Jeff

well done in passing your exam, and welcome to the world of amateur radio

for such a short run you can use pretty much any 50ohm coax, 

a usefull tool is one of the coax loss calculators, loads of them online such as Coax Loss Calculator | KV5R.COM

on the navada site look for the loss at 100mhz, it will be either in 10m or 100m distance, 

on the calculator select the correct cable type, enter 144 for the frequency and the length of your cable run, you will then see how much of your power from your rig will reach the antenna to be radiated out for the different cable type

just remember the thicker the cable generally the lower the loss, BUT the bigger the hole you have to drill to get it outside to the antenna and the harder it is to bend to a radius, 

as you have an estimated 6m run i would suggest 10m of cable, as if you move your rig in the shack or have a measurement slightly wrong you can easilly cut a bit off, but you will be frustrated if its a foot short, and don't leave it with little slack, you can always lose a metre or 2 in a small coil held with a couple of cable ties

also the higher the frequency the higher the loss, and if your antenna is a dual band 2m/70cm a good coax like RG-213 will mean you just need to plug it in the relevant socket at the back depending on the band you want to operate on, or get a 2 way antenna switch and use a few offcuts of coax to make a couple of patch leads to the 2 sockets on the switch and rig

have you start looking at intermediate exam yet? its not a massive jump, just covers the same topics as foundation in a bit more detail

peter

M0PWX

M7 WFR
1 month ago
M7 WFR 1 month ago

Hi Peter,

Thank you for the warm welcome and the good advice.  I will get on to that first thing tomorrow.

Yes, I am looking to do my intermediate asap while I still have all the foundation stuff fresh in my head.  I have started going through one of the intermediate training sites provided by GM6DX https://gm6dx.thinkific.com/users/sign_in, but I am having to learn circuits in more detail, resistors in parallel etc, but I am sure I will be able pick it up.  I work full time, so I have to find time to fit it all in.

Once again thank you for the warm welcome and sound advice and I hope to speak to you over the air some time soon.

 

Kind regards

 

Peter M0PWX (2E0PWX)
1 month ago

Geoff

i used the GM6DX course for my intermediate which i took only 5 weeks after passing my foundation last october, its a good course, 

then used the cornish radio amateur club videos on youtube with the exam secrets for my full license in february

i should say i have a background in electronics and computers, so the electronic theory side was not bad for me

do the practice papers on the RSGB site (Mock exams - Radio Society of Great Britain - Main Site : Radio Society of Great Britain – Main Site (rsgb.org) ), then go through ALL of the questions one at a time to work out why the answers are correct (note the formula used or the license paragraph / clause, you will see areas that get concentrated on) , i found this caused me to look at the license clauses in great detail, and the formula sheet, and in doing so understand how and importantly when to use them in the exam

doing this also shows which areas you need to do more study and go back over the gm6dx modules for those areas

the exam secrets book (Exam Secrets for Radio Amateurs (rsgbshop.org) ) is very useful as it has lots of extra example questions for all 3 exams and the reason why answers are correct

as with most multi choice exams with 4 answers per question, 2 can normally be discounted easily,  leaving a straight choice between two remaining, read them carefully and often you can work out the more likely even if you are not certain

Peter

M0PWX

M7 WFR
4 weeks ago
M7 WFR 4 weeks ago

Hi Peter,

I really appreciate the advice.  I have joined the GM6DX site and I am finding it it very useful, I am not sure I will get anywhere near your impressive five week post foundation intermediate exam result.

I unfortunately do not have a background in electronics and I am finding the electronics challenging and I am on a very steep learning curve at present, but I am quite tenacious and will be tackling the intermediate exam as soon as I feel confident enough to do so.

I will certainly checkout the links and advice you have given and thank you again for taking the time to put this advice together for me.

Apologies for the delayed response, as work commitments persist.

Kind regards 

Peter M0PWX (2E0PWX)
4 weeks ago

the level of knowledge of electronics at intermediate is not excessive,

it is limited mainly to calculate the value of components in series and parallel, and the basic concepts of what each component does

don't over complicate what you need to know

using a meter the main things to  remember are voltage you measure across a component (in parallel) and current you measure inline (in series)

transistors in their simplest form are switches, 

diodes are one way valves for electrons (LED's light up to show electrons are flowing)

resistors are restrictions to flow of electrons, 

capacitors are reservoirs that store charge, they allow AC current to flow but block DC

inductors store energy in magnetic fields

how inductors and capacitors resist the flow of current at different frequency is reactance

youtube and google are you friends, buy a basic multimeter, a small bread board and some basic components and play, radio is all about learning by experimentation, 

buy a simple / basic kids electronic kit from amazon/ebay loads are available

create an LED circuit with a 3v battery, 220 ohm resistor and LED

turn the LED round you find it only lights up in one direction,

change the 220ohm resistor for a 100 ohm one, does it get brighter or dimmer

what happens, try a 330 ohm one, put the 220 ohm and 330 ohm resistors in series and parallel  and see what happen

use you multimeter to measure the voltages and currents, to see what happens to the current and voltages and how they relate to each other (clue ohms law)

when you see things like that and can predict what will happen when you change things makes understanding what's happening so much easier than learning parrot fashion from just reading

you get the idea

just remember the KISS principle and don't over complicate it as the level of knowledge at intermediate level is basic

(KISS = Keep It Simple Stupid)

you only need to get 2/3 of the questions right to pass, or put the other way you can get 1/3 wrong and still pass, so if you struggle with one small topic don't panic it don't stop you passing

Peter M0PWX (2E0PWX)
4 weeks ago

something like this on amazon has all you need

https://www.amazon.co.uk/Electronics-Starter-Kit-Experiments-Transistors/dp/B08KSD8DDK

and a basic meter like ULTRICS Digital Multimeter, Voltmeter Ammeter Ohmmeter Circuit Checker with Backlight LCD Test Leads, Portable Multi Tester Measures OHM AC DC Voltage Current Resistance Continuity Diodes Transistor: Amazon.co.uk: DIY & Tools

these are just examples i found quickly, nothing fancy, as if you do break them not much lost

oscillators are good fun for learning about series and parallel resistors and capacitors, put higher and lower values in the circuit and see how it alters the sound produced, once you understand that, then put them in series and parallel and the tone produced will tell you if there combined values are higher or lower

or use the meter to measure the values after you use calculation to predict the answer, basically use the meter to confirm if you got the calculation correct

have a play and have fun learning, i find things make much more sense if i can get my hands on them to understand how they work

peter

M0PWX

M7 WFR
4 weeks ago
M7 WFR 4 weeks ago

Hi Peter,

I am starting to get through the GM6DX online course, I am already down to the first reactance module.  I have had to learn to use a scientific calculator (fun).  I am having to go over each module several times, but It is all starting to come together, it has taken me a few days to get back into serious learning mode and I have to say I am beginning to enjoy the challenge.

I have ordered the kit and I already own a multimeter, so I am looking forward to putting some theory into practice and like you said for the price of the kit, it is worth creating some basic circuits and then be able to go on to measure them using the meter.

Thanks for the encouragement.

 

Kind regards

Peter M0PWX (2E0PWX)
4 weeks ago

no problems 

enjoy the challenge, if you set yourself up on QRZ.Com you will see my details and background, some pictures of my station etc

if you struggle with a bit of the electronics theory, drop me an email  at

mycallsign at outlook.com

and i will try to help

73

Peter

M0PWX

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