Ham Radio

(See also: Software-Defined Radio)

Ham Radio is an old hobby that has origins as far back as the late 1800's. It was formalized as a hobby in the early 20th century. It is an over-regulated piece of shit, but what isn't now a days.

Ham Radio

Testing In The US

Element 2 Technician 35 out of 426 questions from this pool

Frequencies

80m

40m

15m

10m

6m

2m

1.25m

70cm

33cm

23cm

Element 3 General 35 out of 462 questions from this pool

Frequencies	2200m	630m	160m	80m	60m	40m	30m	20m	17m
15m	12m	10m	6m	2m	1.25m	70cm	33cm	23cm

Element 4 Amateur Extra 50 out of 712 questions from this pool

Frequencies	2200m	630m	160m	80m	60m	40m	30m	20m	17m
15m	12m	10m	6m	2m	1.25m	70cm	33cm	23cm

Find Testing Locations In The US

Get Your FCC Registration Number

You will need either an FCC Registration or Social Security number in order to take the exam. It is not necessary to register beforehand with the FCC, but it will speed things along if you bring the paperwork.

FCC License Data Search

For a fee of $15 USD you may take one or all three tests in one sitting at no additional charge. If you fail a test, you may spend an additional $15 USD to retake it. Your license is good for 10 years with a 2 year grace period to retest after expiration. You are no longer required to know Morse code for any of these tests.

FCC Part 97 The US Amateur Rulebook

Maths You Should Know

Ohm's Law

Solve For Watts	Amp2 x Ohm	Volt2 / Ohm	Volt x Amp
Solve For Volts	Amp x Ohm	√Watt x Ohm	Watt / Amp
Solve For Amps	Volt / Ohm	Watt / Volt	√Watt / Ohm
Solve For Ohms	Volt2 / Watt	Volt / Amp	Watt / Amp2

Speed of Light Is a Constant 299,792,458 Meters Per Second

Wavelength is represented in Meters as λ

Frequency is represented in Mega Hertz as f

Speed of Light c (300MM) / Frequency f (MHz) = Wavelength λ (Meters)

This is the basic formula to find full wavelength in meters for a given frequency.

Antennas

Loop Antennas are full wavelength with one element.

c/f=λ Element Length

Dipoles are half wave with two elements.

c/f/2 = λ/2 Element Lengths

Ground Planes must be at least quarter wave with one vertical and four radial elements.

c/f/4 = λ Vertical Element Length

c/f/4 = λ Radial Element Lengths

3 Element Yagi Yagis are directional antennas consisting of a boom with reflector, driven, and director elements.

c/f = λ*.495 = Reflector Element Length

c/f = λ*.125 = Boom Separation Length

c/f = λ*.473 = Driven Element Length

c/f = λ*.125 = Boom Separation Length

c/f = λ*.440 = Director Element Length

ITU Radio Bands

VLF	LF	MF	HF	VHF	UHF	SHF
3 to 30 kHz	30 to 300 kHz	300 to 3 MHz	3 to 30 MHz	30 to 300 MHz	300 to 3 GHz	3 to 30 GHz

Feedline

RG6 is common and cheap, but higher resistance at 75 Ohms. You should not use this.

RG58 is cheap, 50 Ohms, and perfectly acceptable for HF.

RG8X is slightly more expensive than RG58, but lower loss.

RG213 is double the price of RG58 and RG8X, but lower attenuation at higher frequencies.

RG8U is almost identical to RG213 in price and attenuation, but has lower loss per 100ft.

LMR400 is exceptional at higher frequencies as well as low. If your software radio can do 1GHz-6GHz, this is what you get.

Lightning Protection

If your antenna is outdoors, you should take precaution to prevent yourself and your gear from becoming dead. Metal antenna mounts should be grounded using 10 gauge insulated solid core copper wire. Your coax should have a lightning arrestor between the antenna and your equipment. The arrestor should be mounted near the lightning rod it's grounded to. To prevent moisture ingress, the arrestor and coax connectors should be placed in a plastic electrical box. If you have a wire dipole antenna, you should use ceramic insulators at both ends and guy rope to tie between two points.