This page has recently been reorganized.
Everything is still here; the articles just got grouped together by function.
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The
"Standard Radio Communications Manual" by Harold Kinley WA4GIB (SK) 44MB PDF download.
This excellent book tells how to be a good two-way radio technician with practical examples!
400+ pages of solid info. Well worth reading. Scanned by Skipp for all to enjoy.
Rutger de Haan VA6WOF ran it past a good optical character recognition (OCR) system in June of 2024 and made it text-searchable. THANKS to both!
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Repeater Application notes and Articles offsite link to the Chip Angle N6CA web site.
Look for the "Repeater applications notes" - proven repeater system design techniques from a VHF / UHF / weak signal / contesting fan and RF design guru.
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While it's not worth a separate article, you don't want to have a UHF repeater input in the 100 KHz block between
446.0 and 446.100 in any area frequented by foreign tourists. Why? Personal radio frequencies are not standardized world
wide, and tourists frequently bring their personal radios with them.
The European "PMR 446" service uses 8 channels in the 446.0-446.1 MHz range (complete
with user-selectable CTCSS / DCS codes), specifically: (1) 446.00625, (2) 446.01875,
(3) 446.03125, (4) 446.04375, (5) 446.05625, (6) 446.06875, (7) 446.08125 and (8) 446.09375...
sounds like a good area for digital, Dstar, Fusion, P25 repeater outputs or point-to-point packet links. The same eight frequencies are
used in radios made and sold in Singapore, maybe elsewhere.
Update 2024: It's now 40 channels in the block between 446.0 and 446.200. More details here:
https://en.wikipedia.org/wiki/Personal_radio_service
Japan has a digital "Low Power Community Radio" service that allows 1/2 watt handhelds in the 50 KHz between 142.934375 to 142.984375 MHz
and another 50 KHz between 146.934375 to 146.984375 MHz range... The 142 MHz set is in the USA "government range" and
the 146 MHz set is in the USA two meter repeater band.
South Korea has a personal radio service allowing
5 watts on 25 channels across 0.5125 MHz between 448.75 and 449.2625 MHz (complete with user-selectable CTCSS / DCS codes).
The eleven highest frequencies can be paired with frequencies in the 424 MHz range.
Other countries have other personal radio services but these are all that I know of that affect USA amateur radio frequencies. Updates are welcome.
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Monolithic Crystal Filter
Application in Amateur VHF Repeaters 208 kb PDF by Joseph M. Hood K2YAH
Mr. Hood describes how a crystal filter can be placed in front of a VHF repeater receiver to
reduce desense and intermod. Filters have insertion loss, you will want to have enough signal there to start with.
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Some thoughts on low band (6 meter and 10 meter) repeaters by Mike Morris WA6ILQ
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How about 1200 MHz? Any thoughts on this? A reply by Jeff DePolo WN3A.
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1200 MHz / 23 cm repeaters in the U.K. by Andy G8VLL
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Terminology used around repeaters
An ongoing glossary updated semi-regularly. Contributions / Critiques / Corrections / Updates welcome.
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Why should you really spend $50 to re-crystal a Motorola channel element
or GE ICOM? by Kevin Custer W3KKC, Jeff DePolo WN3A, Robert Meister WA1MIK (SK), Eric Lemmon
WB6FLY (SK), and Mike Morris WA6ILQ.
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Temperature-Compensated Xtal Oscillator (TCXO) tutorial 228 kb PDF by Vectron
Vectron is a company known for precision crystal oscillators. This is good reading along with the above article.
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Crystal Technology Design Guidelines 2.4 MB PDF by Motorola, dated May 1990
This is the very technical information they used to send to crystal manufacturers. There is a LOT of good theory here.
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Amateur FM and Repeaters from QST magazine October 1969 513 kB PDF by Les Cobb W6TEE and Jay O'Brien W6GDO (SK)
This article is an overview of Amateur FM and repeaters and despite the date, the ARRL didn't "get"
repeaters and remote bases until about 10-15 years later (Wayne Green W2NSD and 73 magazine were the
driving force as he ran a slew of FM and repeater articles in the late 1960s and all of the 1970s).
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Modulation Standards For VHF FM from Ham Radio magazine June 1970. 5.6 MB PDF by Les Cobb W6TEE
Subtitled "A discussion of modulation circuits and techniques to improve the performance of FM systems."
This article is a technical analysis of the wideband (+/- 15 KHz) and narrowband (+/- 5 KHz) modulation standards.
With the conversion from narrowband to even lesser deviation standards today it's worth reading to understand the
history and to see where things have come from.
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The Remote Base - An Alternative to Repeaters from Ham Radio
magazine April 1977. 2.2 MB PDF by Gordon Schlesinger WA6LBV, and William F. Kelsey WA6FVC
Recommended reading for those wishing to relieve congestion on the VHF bands - a definitive description of the difference
between remote-base stations and repeater stations.
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Two Meter FM repeater separation - 20 KHz Yes, 15 KHz No from Ham Radio
magazine August 1985. 627 kB PDF by Chris Kelly WD5IBS and Virgil Leenerts WØINK
Transmitters with 5 KHz deviation and a 3 KHz audio cutoff create a signal at least 13 KHz wide (and with 4 KHz cutoff
it goes out to 16 KHz), counting only the first set of sidebands. This clashes with 15 KHz channel spacing and is why the
145 MHz repeaters are 20 KHz spaced and why many states went from 15 KHz to a 20 KHz channel bandplan on
146-147 MHz repeaters. This article gives both theoretical and practical information and proves the point (through actual
VHF FM receiver selectivity measurements - don't believe the manufacturer's specs) that you have more usable repeater
pairs using 20 KHz spacing than with 15 KHz spacing.
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Receiving System Degredation in FM Repeaters
228 KB PDF by J. A. Murphy K5ZBA (SK)
An excellent writeup on how to improve the performance of your repeater receiver (10 meters, 6 meters, VHF,
220 MHz, UHF and 1200 MHz). From Ham Radio magazine for May 1969.
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How do I link two or more systems together? by Kevin K. Custer W3KKC and Mike Morris WA6ILQ
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How can I bring a phone line to my hilltop repeater site? by Kevin K. Custer W3KKC and Mike Morris WA6ILQ
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Programming your repeater controller without a radio or a phone line by Mike Morris WA6ILQ
The S-Com 7K controller is programmed with DTMF and is a "write-only" device. Mike needed to program his with a computer... and he wrote the article so that you could use the techniques and circuits to program ANY DTMF device.
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Repeater Courtesy Beeps by Mike Morris WA6ILQ
A table of sample tone info plus telephone call progress tone specs.
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How do receiver voting receivers and voting comparators work? by Mike Morris WA6ILQ
What is a voter? How does it work? An overview of receiver voting systems.
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How does a Voter and Remote Receiver work? by Duane Hall and Kevin Custer W3KKC
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Some Thoughts on Solar Power and Other Off-The-Grid Repeaters by Mike Morris WA6ILQ
Some ideas on what to do when there's no mains power line...
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Adding a Separate Control Receiver to a System That Doesn't Have a Spare Controller Port By Mike Morris WA6ILQ
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Weather radios, SAME decoders, and amateur repeaters by Mike Morris WA6ILQ
Yes, you can have a weather alert or warning receiver automatically activate your repeater - as long as you stay within the rules...
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A Phone Line Busy Sensing Circuit by Monte Smith, WDØDIR
Originally from ACC Notes, April 1986.
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A DTMF / TouchTone / Touch-Tone / Touch-Code Signaling Primer by Mike Morris WA6ILQ
"TouchTone" was the Bell System trademark, so the industry used DTMF as the generic... (but Bell later placed "Touch Tone" and "TouchTone" (without the space) into public domain). "Touch Code" is Motorola's trademark...
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A very interesting Pacific Bell press release from 1990 that
a number of California repeater and remote base operators have used to force Pacific Bell to grant residential phone rates
to mountaintop radio sites. The arguments made are simple and compelling and might work anywhere. Well worth reading!
(The monthly rate certainly has changed!)
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Why every repeater-using ham owes Art Gentry W6MEP a debt of thanks 390 kB PDF by Bill Pasternak WA6ITF, from QST March 2004.
The true story of how one man started a repeater revolution. Hoist a beer and toast Art each May 10th. If you own or use a repeater (on any band) you owe him.
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A collection of repeater-oriented articles by Peter Policani,
K7PP
These articles were published on his own site that has since left the web. Peter graciously gave Repeater-Builder permission to host them here.
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P25 Training Guide 514 kB PDF
Written by Daniels Electronics, Ltd. This 100+ page file is a basic education on P25 digital radio systems. It all started with IMBE (Improved Multi-Band Excitation).
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Some notes on Simulcasting by Richard Cohen K6DBR and Steve Bosshard NU5D
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A Comparison of the HamGadgets ID-O-Matic and the Com-Spec ID-8 and the Midian ID-1 by Robert Meister WA1MIK (SK)
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USA Spectrum Allocation Chart 95 kB PDF
The official chart straight from the US National Telecommunications and Information Administration (NTIA) Office of Spectrum Management (OSM)
Alternate source - from the NTIA server: http//www.ntia.doc.gov/osmhome/allochrt.pdf
(offsite link)
If anyone has pointers to other countries please share them with the page maintainer.
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How to look up an FCC ID number
Sometimes being able to determine who made that device is sometimes very useful... (offsite link - to the FCC server)
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How to look up towers
Search all of the FCC registered towers - broadcast, cellular, everything... (offsite link - to the FCC server)
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Tower lookup page at the FCC web site
(offsite link - to the FCC server)
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VHF Marine channel application and frequency table
USA Use
(offsite link to the US Coast Guard Navigation Center web page)
USA FCC marine channel list
(offsite link to the USA Federal Commmunications web page listing the VHF marine channels)
International Use 20.5
kB PDF
While marine channels are not amateur repeater oriented having a little knowledge of the marine channels is useful so that you know where
your spurs are and what they are landing on...
And these frequencies are sometimes used for something else, especially away from waterways - for example 156.075 MHz is a marine
frequency but it's also "CALCORD - California On-Scene Emergency Coordination - to be used in mobile and portable units at the scene of
any emergency incident requiring coordinated action by more than one agency. Yes, it is also Coast Guard channel 61A, but (the state)
licensed it out of the old Highway Maintenance pool in the early 1960s long before VHF marine was popular. No base stations are allowed (FCC regulation)."
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The FCC Class of Station Code list 35 kB PDF
Ever wonder what an FB2J, or an FB4, or an FB6L is? And why an FB8 is preferred over an FB6?
This is a local copy of the one at the Percon Corporation web site.
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Understanding the FCC Transmitter Emission Codes
Ever wonder what 20K0F3E means, and how it was invented? This is a "Rosetta Stone" article.
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FCC Transmitter Emission Codes 52 kB PDF
A full explanation of the each position of the seven-character emission code.
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A list of the USA Television Channels 3 KB PDF
This is from back in the days when there were 83 channels and 800 MHz was TV, television stations once had
Channels 2 to 83, except for 37 (609.25 MHz to 613.75 MHz), which is reserved for radio astronomy. Channels 14-20 (470-512 MHz) were reallocated
to Land Mobile radio in many areas (the so-called "T-band" or "top" band - and the TV people want it back).
Channels 70 to 83 (807.25 MHz to 889.75 MHz) disappeared in the 1980s and have been reassigned to other uses, including
public safety. The broadcasters gave up channels 52 to 69 (699.25 MHz to 805.75 MHz) in 2009 as part of the transition to digital TV,
and much of that has already been reassigned. As of Febuary 2012 channels 31 to 51 (573.25 MHz to 697.75 MHz), excluding 37 (609.25 MHz to 613.75 MHz), could be reallocated.
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An explanation of Audio Processing by Jeff DePolo WN3A
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Flat Audio, and Pre- and De-Emphasis explained
by Morris, DePolo, Schmid, and Custer
Summarized (and expanded on) from a 1999 email discussion on the Repeater-Builder mailing list.
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Explanation of "Flat Audio" 300
kB PDF by Jeffrey "Shorty" Stouffer K6JSI
This is an 11 page article written in 2004 for a club newsletter. Shorty describes how FM two-way radio works,
why we have pre- and de-emphasis, then he gets into repeaters and when and why to use flat audio. It looks
like he borowed a lot from the Morris, DePolo, Schmid, and Custer article immediately above.
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Pre- and De-Emphasis, Explanation and Assistance:
Running the Numbers by Matt Lechliter W6XC
Matt builds on the principles from the Morris, DePolo, Schmid, and Custer article above.
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More on why Pre-emphasis and De-emphasis, with examples on the Motorola MICOR by Paul Sexauer K3VIX
Paul contributes to the topic with info based on 26 years in engineering with Motorola.
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A Discussion on Repeater Audio Standards by Karl Shoemaker, AK2O (offsite link - will open in a new window)
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Some Thoughts on Radio Programming
Computers and Laptops If you do a lot of radio programming you might want to consider dedicating a laptop to radio programming.
This article describes what the author uses and why…
He has equipment at several mountaintop repeater sites, and prefers the CF‑series Toughbooks.
Note that the above article is an opinion piece… What works for him may or may not work for you…
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ChipDir The Master Chip Lookup Web Site (offsite link to a Dutch server)
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A Comparison Table of Capacitance Values by Mike Morris WA6ILQ
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A catalog of GE miniature and sealed beam lamps 12.4 MB PDF
Info on pilot lights, round and rectangular sealed beam headlights, PAR series lights,
Festoon lights, neon lights, electronic discharge fluroescent lamps, and more.
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Poor Man's Spectrum Analyzer Spectrum
Analyzer Kit by Science Workshop
This web pointer goes to an archived web page (from November 2017 that is at www.archive.org), NOT to the actual science-workshop.com
server as they don't exist any more.
This link is offered only as information, there are SDR receivers and software applications that function as a inexpensive spectrum analyzer.
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Modulation Spectrums by
Robert W. Meister WA1MIK
How audio frequency, filtering, and deviation affect your transmitted FM signal, how to prevent excessive deviation and
splatter, shown with dozens of spectrum analyzer traces.
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A very good primer on basic, single-supply, op-amp circuits 160 kB PDF
A Texas Instruments Application Note (number SLOA058 dated November 2000).
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Op-Amp Design Reference 2 MB PDF
Another Texas Instruments Application Note (number SLOD006B, dated August 2002). This
one has a lot more technical detail info than the primer above.
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Allied Electronics Data Handbook, 2nd
edition (1958) 6.7 MB PDF
A classic electronics reference, about 64 pages. Chock-full of old component and wiring color
codes, formulas, conversion tables, coil winding nomographs, tube substitution data, etc.
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Allied Electronics Data Handbook, 4th
edition (1964) 3.8 MB PDF
Newer version of the above reference, about 88 pages. This one includes transistor circuits.
Sold for a whopping fifty cents when new. Very nice scan.
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Allied Electronics Data Handbook, 5th
edition (1969) 4.5 MB PDF
Yet another edition of this classic electronics reference, 112 pages. Chock-full of all
sorts of useful information from the vacuum tube era.
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MIL Handbook 413 12 MB PDF
A design handbook for high frequency radio communications systems. Has info on just about every modulation system known to man,
as well as antenna systems, transmission lines, ground systems, modems, etc.
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FAA Advisory Circular 20-136B: Aircraft Electrical and Electronic System Lightning Protection 125 kB PDF
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FAA Standard 019e: Lightning and Surge Protection,
Grounding, Bonding and Shielding Requirements for Facilities and Electronic
Equipment 1 MB PDF
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Grounding in Central Office and Remote Electronic
Equipment Environments 5.4 MB PDF
A CenturyLink Technical Publication.
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The application of relay coil suppression with
DC relays 33 kB PDF
An application note from the back of a Leach Relays catalog.
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Glossary of Tone Signaling terms 300 kB PDF
As used with Tone Signaling, Data Signaling, Remote Control, Voice Scrambling, Radiotelephone
Interconnect. From Midian Electronics.
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Motorola Semiconductor Data Book 22 MB PDF
Diodes, transistors, digital and linear ICs from this 1966 version. Over 1,500 pages.
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Motorola Semiconductor Data Book 29 MB PDF
Diodes, transistors, digital and linear ICs from this 1988 version. Over 2,150 pages.
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Motorola Communications Parts and Data
Book 16.4 MB PDF - will open in a new window
Mike WA6ILQ scanned all 222 pages of the so-called "Silver Book" (from the color of the silvery cloth binding).
This hard-back book was limited in circulation (Mike got his as a gift from a repair shop owner that ended up with two by accident).
It contains conversion charts, antenna data sheets, radios, accessories, replacement part lists, you name it. Chock-full of stuff
for Motorola radio products from the late 1970s including the Micor and Mitrek. Not the best scan but definitely usable.
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National Semiconductor CMOS Data book (1988 version) (offsite link -
local copy - downloadable - will open in a new window)
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Motorola Semi - RF Device Data Volume 1 (1998 version) (offsite link -
local copy - downloadable - will open in a new window)
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Motorola Semi - RF Device Data Volume 2 (1998 version) (offsite link -
local copy - downloadable - will open in a new window)
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Motorola CMOS Data Book DL131/D Rev 3 (1991) 6.9 MB PDF
This is a scan of the actual data book on Motorola’s entire MC14000 series CMOS products.
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