1. Chapter 25: UHV/VHF Operation

2. Introduction: First Contacts
For most amateurs, their first solo-contacts tend to be on 2m or 70cm (VHF/UHF respectively)
Recall: 2m = MHz & 70cm = MHz
Only basic qualifications required
Affordable equipment for under $100
Relatively simple operating procedures
Offers best introduction to local (established) amateurs

3. VHF/UHF: Basic overview2M
1.25m
70cm
Frequencies
MHz
MHz
MHz
Band Size
4 MHz
5 MHz
20 MHz
Maximum Bandwidth
30 kHz (FM-wide)
100kHz
12 MHz (DSS)
Calling Frequency
MHz – CW
MHz – FM
222.1 MHz – CW
222.2 MHz – SSB
432.1 MHz – CW
432.2 MHz – SSB
446.0 MHz – FM
Typical Repeater Offset
0.6 MHz
Common Uses
CW, Voice, APRS, Packet, Satellite (U/L)
CW, Voice, Packet
CW, Voice, Packet, Satellite (D/L), ATV
Less Common Uses
Remote linking, Moonbounce,

4. Operating: Basic Guidelines
Listen, Listen, Listen!
No matter what the frequency, ensure that you will not interrupt a contact in-progress before transmitting
By listening first, you learn the established etiquette on-air
Use only the minimum power necessary to conduct a contact
When using a “calling frequency” be sure to QSY once established
Determine a mutually agreed frequency and move to it to continue chatting
Always comply with the Radiocommunication Act

5. QSO: Methods of making a contact
There are three possible schemes for making a contact:
Simplex
Half-Duplex
Full-Duplex
Each method has benefits and drawbacks
Ease of implementation
Cost of hardware associated
Etc..

6. Simplex: The most basic QSO
Any method of communication which uses the same frequency for transmission and reception
Only one person may transmit at a time, otherwise, you are “doubling” over each other
Simplest form of communication
Ex: Walkie-Talkies as a kid

7. Duplex: Using different TX/RX Freq.
Duplex (half and full) is any method of communication which uses different transmit and receive frequencies
Half-duplex:
As with simplex, only one person may transmit at a time for effective communication
Repeaters commonly operate as half-duplex
Full-duplex:
Seldom used due to the technical challenges
Common example is the cellular telephone

8. Repeaters: A Primer
Repeaters are a very popular resource in amateur radio
Frequently used by local residents to improve their “coverage area”
Many local “nets” are hosted on repeaters because of their enhanced coverage area
May be used to link distant geographic locations via RF
Eg. VE2REH network in Quebec
Internet
IRLP, Echolink
147.3 MHz
147.9 MHz

9. Repeaters: Major Types
What:
Any radio station which automatically retransmits an input signal to increase the effective range of the original signal
Generally placed in a highly favourable location such as top of a tall building, mountain-top, etc.
Simplex
Half-Duplex
Full-Duplex
Cross-Band --
HT → Car → APRS iGate
Satellite Operation
Same-Band
“Parrot-Box”
Standard
Repeater
WiFi & Digital “repeaters”

10. Repeaters: Privileges
Basic licensee:
Use any open repeaters with operating frequencies which are within the permitted range of the user (ie. your privileges)
Basic (70% < 80%) can use only those repeaters which operate on: 6m, VHF, UHF
Basic+ (≥80%) may use any repeaters, even those which theoretically retransmit on HF
Own/operate a cross-band repeater
In addition to Basic privileges, an Advanced operator may
Own/operate a same-band repeater
Repeater is generally given its own callsign and the input/output frequency pairs are supposed to be managed by a repeater council
Must conform to all Radiocommunication Act requirements
Ie. station identification at least every 30 minutes

11. Repeaters: How It Works
Simply take an incoming signal and retransmit at higher power, generally in the same band but on a slightly different frequency (the offset)
Generally done with two commercial radios designed for this purpose (100% duty cycle)
Repeater is generally controlled via DTMF tones and a controller board
Handles on/off operation, CTCSS tones, identification
When operating in the same band, a cavity filter (very high Q) is frequently used so that the same antenna can be used for simultaneous TX/RX

12. Coded Squelch: Preventing Noise
Sub audible tones used in (RF) noisy environment to trigger a radio’s squelch only when a signal with the associated coded squelch is present
Two major code types:
CTCSS
Continuous Tone-Coded Squelch System
DCS/DTCS
Digitally (Tone) Coded Squelch

13. CTCSS: Most Common As many as 50 sub-audible tones
Originally only 32 tones, but was adapted to incorporate PL tones (Motorola)
67.0 Hz
94.8 Hz
131.8 Hz
171.3 Hz
203.5 Hz
69.3 Hz
97.4 Hz
136.5 Hz
173.8 Hz
206.5 Hz
71.9 Hz
100.0 Hz
141.3 Hz
177.3 Hz
210.7 Hz
74.4 Hz
103.5 Hz
146.2 Hz
179.9 Hz
218.1 Hz
77.0 Hz
107.2 Hz
151.4 Hz
183.5 Hz
225.7 Hz
79.7 Hz
110.9 Hz
156.7 Hz
186.2 Hz
229.1 Hz
82.5 Hz
114.8 Hz
159.8 Hz
189.9 Hz
233.6 Hz
85.4 Hz
118.8 Hz
162.2 Hz
192.8 Hz
241.8 Hz
88.5 Hz
123.0 Hz
165.5 Hz
196.6 Hz
250.3 Hz
91.5 Hz
127.3 Hz
167.9 Hz
199.5 Hz
254.1 Hz

14. DCS: Seldom Used
DCS superimposes FSK data (134.4bps) onto the transmitted signal
Similar to CTCSS, the DCS data serves to prevent squelch opening unless the correct data is received
Has great potential, however, control boards are more cumbersome to implement

15. Repeaters: How to start
To use a repeater, you need some information:
Repeater’s TX & RX frequencies
Repeaters are listed by the frequency at which they transmit
You must determine the repeater’s receive (listening) frequency by using the offset for the band the repeater is operating on
Control tone(s) (if used)
Often used in radio-congested areas to reduce unwanted retransmission of garbage
Generally listed with the repeater’s TX frequency

16. Repeaters: Simple Example
Let’s use VE3TWO as an example. It is listed simply as:
This is the repeater’s transmit frequency
Following convention, we know that repeaters which operate on 2m use 0.6 MHz as the offset value (unless otherwise stated)
The (+) means a positive offset frequency for the repeater’s receive frequency so we add 0.6 MHz to determine the “listening” frequency
147.3 MHz MHz = MHz
VE3TWO MHz (+)

17. Repeaters: Advanced Example
Suppose a repeater is listed as:
To use the repeater, set your radio to:
RX on MHz
using CTCSS tone on receive
TX on MHz
using CTCSS tone on transmit
*unless otherwise stated, assume that CTCSS tones are listed as (out/in)
VE3FAKE MHz (-) (151.4 / 110.9)*

18. A’s Incoming 70cm RF link locked out by 2m reception (in use)
Repeater Linking: RF
Repeaters may be linked to each other by an RF link to increase total coverage area
When you transmit on repeater A’s input (listen) frequency, all repeaters (including A) retransmit your signal
“Hi Tom..”
147.4 MHz
“Hi Tom..”
A’s Incoming 70cm RF link locked out by 2m reception (in use) B
Blue = 2m “open repeater” frequency
Red = 70cm “rf link” frequency
you
distant
station
(Tom)
PTT is pressed
MHz
MHz
MHz
“Hi Tom..”
147.4 MHz(-)
MHz (+0.6) A C
146.3 MHz
MHz
MHz
“Hi Tom..”
MHz(-)
MHz (-0.6)
146.3 MHz(+)
MHz (-0.6)

19. Repeater Linking: Internet
IRLP
Internet Radio Linking Project
Radio↔ Repeater (A)
Repeater (B) ↔ Radio
MHz(+)
Node: 2001
146.7 MHz (-)
Node: 2002
Internet
Using your radio which is set to: (TX MHz, RX MHz) you would link to the distant repeater by pressing: “2002” on the DTMF keypad while holding the PTT button
Once the IRLP link is established, you could then transmit to your local repeater and have the distant repeater (B) retransmit at 146.7MHz

20. Repeater Linking: Echolink
Echolink is similar to IRLP with the exception that you can link to distant repeaters directly from a computer, dropping the radio-to-repeater portion of the link
Theoretically possible to have straight echolink-to-echolink contacts without even using a radio
Not really radio any more, huh?