Technical Information Index (2024)

Contributions / Critiques / Corrections / Updates are ALWAYS welcome!

There are other good articles on the Construction Projects page.

This page has recently been reorganized.
Everything is still here; items just got grouped together by function.

Repeater-Related Information:

	The "Standard Radio Communications Manual" by Harold Kinley WA4GIB (SK) 44MBPDF 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. Note: This PDF was created by scanning the book and hence is an image scan, therefore it is not text searchable)
	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.
	While it's not worth a separate article, you don't want to have a UHF repeater input in the 100KHz 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 "PMR446" service uses 8 channels in the 446MHz 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. Japan has a digital "Low Power Community Radio" service in the 50KHz between 142.934375 to 142.984375MHz and another 50KHz between 146.934375 to 146.984375MHz range... The 142MHz set is in the "government range" in the USA, the 146MHz set is in our 2meter repeater band. South Korea has a personal radio service allowing 5 watts on 25 channels across 0.5125MHz between 448.75 and 449.2625MHz (complete with user-selectable CTCSS/DCS codes). Other countries have other personal radio services but these are all that I know of that affect USA amateur radio frequencies. Updates are welcome.
	Monolithic Crystal Filter Application in Amateur VHF Repeaters 208 kbPDF 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.
	Some thoughts on low band (6meter and 10meter) repeaters by Mike Morris WA6ILQ
	How about 1200 MHz? Any thoughts on this? A reply by Jeff DePolo WN3A.
	1200 MHz/23 cm repeaters in the U.K. by Andy G8VLL
	Terminology used around repeaters An ongoing glossary updated semi-regularly. Contributions / Critiques / Corrections / Updates welcome.
	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.
	Temperature-Compensated Xtal Oscillator (TCXO) tutorial 228kbPDF by Vectron Vectron is a company known for precision crystal oscillators. This is good reading along with the above article.
	Crystal Technology Design Guidelines 2.4MBPDF 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.
	Amateur FM and Repeaters from QST magazine October 1969 513kBPDF 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 73magazine were the driving force as he ran a slew of FM and repeater articles in the late 1960s and all of the 1970s).
	Modulation Standards For VHF FM from Ham Radio magazine June 1970. 5.6MB 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 (+/- 15KHz) and narrowband (+/- 5KHz) 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.
	The Remote Base - An Alternative to Repeaters from Ham Radio magazine April 1977. 2.2MB PDF by Gordon SchlesingerWA6LBV, and William F. KelseyWA6FVC 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.
	Two Meter FM repeater separation - 20KHz Yes, 15KHz No from Ham Radio magazine August 1985. 627 kBPDF by Chris KellyWD5IBS and Virgil LeenertsWØINK Transmitters with 5KHz deviation and a 3KHz audio cutoff create a signal at least 13KHz wide (and with 4KHz cutoff it goes out to 16KHz), counting only the first set of sidebands. This clashes with 15KHz channel spacing and is why the 145MHz repeaters are 20KHz spaced and why many states went from 15KHz to a 20KHz channel bandplan on 146-147MHz 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 20KHz spacing than with 15KHz spacing.
	Receiving System Degredation in FM Repeaters 228KBPDF by J. A. MurphyK5ZBA (SK) An excellent writeup on how to improve the performance of your repeater receiver (10meters, 6meters, VHF, 220MHz, UHF and 1200MHz). From Ham Radio magazine for May 1969.
	How do I link two or more systems together? by Kevin K. Custer W3KKC and Mike Morris WA6ILQ
	How can I bring a phone line to my hilltop repeater site? by Kevin K. Custer W3KKC and Mike Morris WA6ILQ
	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.
	Repeater Courtesy Beeps by Mike Morris WA6ILQ A table of sample tone info plus telephone call progress tone specs.
	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.
	How does a Voter and Remote Receiver work? by Duane Hall and Kevin Custer W3KKC
	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...
	Adding a Separate Control Receiver to a System That Doesn't Have a Spare Controller Port By Mike Morris WA6ILQ
	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...
	A Phone Line Busy Sensing Circuit by Monte Smith, WDØDIR Originally from ACC Notes, April 1986.
	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 TouchTone into public domain). "Touch Code" is Motorola's trademark...
	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!)
	Why every repeater-using ham owes Art GentryW6MEP a debt of thanks 390kBPDF 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.
	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.
	P25 Training Guide 514 kBPDF Written by Daniels Electronics, Ltd. This 100+ page file discusses and explains just about everything you'd ever need to know about P25 digital radio systems. It all started with IMBE (Improved Multi-Band Excitation).
	Some notes on Simulcasting by Richard Cohen K6DBR and Steve Bosshard NU5D
	A Comparison of the HamGadgets ID-O-Matic and the Com-Spec ID-8 and the Midian ID-1 by Robert Meister WA1MIK (SK)

Tone Squelch (CTCSS, PL, CG, QC, QT, etc) Information:

	How much PL Deviation should I run? by Kevin K. Custer W3KKC
	Eliminating the long squelch noise bursts when using CTCSS (PL / CG) by Kevin K. Custer W3KKC The use of "AND Gating" of the logic signals.
	A Historical and Technical Overview of Tone Squelch Systems by Mike Morris WA6ILQ A primer on tone systems, with a little on digital systems.
	Two-way Radio CTCSS and DCS Codes Compiled by Robert W. Meister WA1MIK (SK) This started as the standard list of Motorola PL and DPL codes extraced from an RSS Help file but it has been expanded to include lists from Icom, Kenwood, and Yaesu. Updates are welcome.
	CTCSS Frequency vs Decode Time by Robert W. Meister WA1MIK (SK) The myth is that lower PL frequencies take longer to decode than higher ones, and it was probably true a long time ago. This article shows the results of tests made with several microprocessor-controlled radios as well as one that still uses mechanical reeds. The results were surprising, and the answer is: it depends.
	CTCSS Doesn't Fix Anything! by Mike Morris WA6ILQ Why PL, CG or CTCSS is NOT a cure for interference.
	A Chart of CTCSS Tone Numbers by Mike Morris WA6ILQ Why tone numbers are useless!
	Analyzing Some Motorola PL Reverse Burst Circuits by Robert W. Meister WA1MIK (SK) Most radios use a 180 degree phase shift... except Motorola.

FCC-Related Information:

	USA Spectrum Allocation Chart 95 kBPDF 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.
	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)
	How to look up towers Search all of the FCC registered towers - broadcast, cellular, everything... (offsite link - to the FCC server)
	Tower lookup page at the FCC web site (offsite link - to the FCC server)
	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 kBPDF 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 156.075MHz 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 long before VHF marine was popular (early 1960s). No base stations are allowed (FCC regulation)."
	The FCC Class of Station Code list 35 kBPDF 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.
	Understanding the FCC Transmitter Emission Codes Ever wonder what 20K0F3E means, and how it was invented? This is a "Rosetta Stone" article.
	FCC Transmitter Emission Codes 52 kBPDF A full explanation of the each position of the seven-character emission code.
	A list of the USA Television Channels 3 KBPDF This is from back in the days when there were 83 channels and 800MHz was TV, television stations once had Channels 2 to 83, except for 37, which is reserved for radio astronomy. Channels 14-20 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 disappeared in the 1980s and have been reassigned to other uses, including public safety. The broadcasters gave up channels 52 to 69 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, excluding 37, could be reallocated.

RF-Related Information:

	Comprehensive guide to understanding transmitter combiners with lots of theory and examples. by Neil Johnson WBØEMU
	How do I measure sensitivity on this FM receiver? by Jeff DePolo WN3A
	Measuring Sensitivity - SINAD vs Quieting by Robert W. Meister WA1MIK (SK) There are two standard ways to measure sensitivity, and this article compares them, complete with clickable audio files.
	Measuring Receiver Effective Sensitivity by Chris Boone WB5ITT Repeater receiver sensitivity measurements on the workbench are irrelevant - all that really counts is how well it works at the repeater site.
	Speaking of Preamps... An interesting discussion thread about 900 MHz preamps extracted from the AR902MHz Yahoo! Group. The information presented herein is applicable to other bands as well.
	Fundamentals of RF and Microwave Noise Figure Measurements 712 kBPDF Appnote 57-1 by Agilent Technologies (the old HP Instrument Division)
	10 Hints for Making Successful Noise Figure Measurements 967 kBPDF Appnote 57-3 by Agilent Technologies (the old HP Instrument Division)
	Practical Noise-Figure Measurement and Analysis for Low-Noise Amplifier Designs 1.7MB PDF Appnote 1354 by Agilent Technologies (the old HP Instrument Division)
	Receiver Noise Figures 458 kBPDF by Richard J. Mohr
	Resolving high-band paging transmitter interference by Bryan Dorbert N3ST
	900 MHz Frequencies to Avoid When You Set Up Your New Repeater There's a lot of grunge on 900 MHz and amateur radio is secondary there, and we just have to avoid it. Here's a list of channels to avoid, plus some important information that restricts amateur use in some areas of the United States. (This article is very dated, but still useful)
	How to install RF modules and transistors by RF Parts company A step-by-step procedure from the experts.
	But it's only a couple of dB! by Mike Morris WA6ILQ Feed line (and connector) losses really DO add up!
	dB to voltage conversion table (both 50 ohm and 75 ohm) by Mike Morris WA6ILQ
	dBm to watts, rms, peak, and peak-to-peak voltage conversion table for 50 ohm systems
	Decibel (dB) Tables (Common Ratios) 97 kBPDF
	Return Loss (dB) vs VSWR Table 30 kBPDF
	Building Your Own CATV Hardline Matching Transformers by Kevin Custer W3KKC 75 ohm TV hardline is cheap and here's how to match it to a 50 ohm system
	CANUSA Heat Shrinkable Tubing by Kevin Custer W3KKC Great for sealing antenna and coax joints
	Phase Noise Measurement Using the Phase Lock Technique 330 kBPDF AppNote 1639 by Freescale Semiconductor, Inc.

AC and DC Power-Related Information:

	AC Power Information - Safety Issues when dealing with commercial AC power by Mike Morris WA6ILQ
	Amateur Radio Bonding and Grounding by Dereck Campbell KF5LJW A very detailed analysis of bonding and grounding systems and methods you can use to improve the safety of your shack and mobile installations.
	Grounding and Bonding for Network Facilities - Design Fundamentals 1.3MB PDF by AT&T An official AT&amp&T document that describes the concepts they use when designing their own network facilities. You'll see examples of a lot of what Dereck talks about in his article above.
	NEMA Non-Locking plugs and receptacles configuration 480kBPDF published by Qualtek
	NEMA Twist-Lock plugs and receptacles configuration 590 kBPDF published by Qualtek
	Single and Three-Phase AC Power Distribution Configurations 1.1MB PDF published by Ametek
	Capacitors Age and Capacitors Have an End of Life 405 kBPDF from Emerson Corporation This writeup is oriented towards Uninterruptible Power Systems - the battery charger and inverter systems that back up hospitals, etc. UPS systems use large capacitor banks. Our repeater power supplies also use large capaciitors in the DC power supplies. This white paper discusses large DC aluminum electrolytic and AC polymeric film capacitors for use in a UPS application: specifically field aging, failure modes, expected service life and preventative maintenance.
	Power Supply Technical Guide 4.57MB PDF Written by XPPower, this 150 page file covers power supplies, UPSes, and other AC and DC power-related topics.
	Power Supply Load Tests by Eric Lemmon WB6FLY (SK) These load tests were uploaded to the repeater-builder group files section and were recently recovered and posted here. Some are duplicated on other pages of this site.

Audio-Related Information:

	An explanation of Audio Processing by Jeff DePolo WN3A
	Flat Audio, and Pre- and De-Emphasis explained by Morris, DePolo, Schmid, and Custer Summarized from a 1999 email discussion on the Repeater-Builder mailing list.
	Explanation of "Flat Audio" 300 kBPDF 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.
	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.
	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.
	A Discussion on Repeater Audio Standards by Karl Shoemaker, AK2O (offsite link - will open in a new window)

Reference and Miscellaneous Information:

	ChipDir The Master Chip Lookup Web Site (offsite link to a Dutch server)
	A Comparison Table of Capacitance Values by Mike Morris WA6ILQ
	A catalog of GE miniature and sealed beam lamps 12.4MB PDF Info on pilot lights, round and rectangular sealed beam headlights, PAR series lights, Festoon lights, neon lights, electronic discharge fluroescent lamps, and more.
	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.
	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.
	A very good primer on basic, single-supply, op-amp circuits 160 kBPDF A Texas Instruments Application Note (number SLOA058 dated November 2000).
	Op-Amp Design Reference 2MB PDF Another Texas Instruments Application Note (number SLOD006B, dated August 2002). This one has a lot more technical detail info than the primer above.
	Allied Electronics Data Handbook, 2nd edition (1958) 6.7MB 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.
	Allied Electronics Data Handbook, 4th edition (1964) 3.8MB 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.
	Allied Electronics Data Handbook, 5th edition (1969) 4.5MB PDF Yet another edition of this classic electronics reference, 112 pages. Chock-full of all sorts of useful information from the vacuum tube era.
	MIL Handbook 413 12MB 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.
	FAA Advisory Circular 20-136B: Aircraft Electrical and Electronic System Lightning Protection 125 kBPDF
	FAA Standard 019e: Lightning and Surge Protection, Grounding, Bonding and Shielding Requirements for Facilities and Electronic Equipment 1MB PDF
	Grounding in Central Office and Remote Electronic Equipment Environments 5.4MB PDF A CenturyLink Technical Publication.
	The application of relay coil suppression with DC relays 33 kBPDF An application note from the back of a Leach Relays catalog.
	Glossary of Tone Signaling terms 300 kBPDF As used with Tone Signaling, Data Signaling, Remote Control, Voice Scrambling, Radiotelephone Interconnect. From Midian Electronics.
	Motorola Semiconductor Data Book 22MB PDF Diodes, transistors, digital and linear ICs from this 1966 version. Over 1,500 pages.
	Motorola Semiconductor Data Book 29MB PDF Diodes, transistors, digital and linear ICs from this 1988 version. Over 2,150 pages.
	Motorola Communications Parts and Data Book 16.4MB 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.
	National Semiconductor CMOS Data book (1988 version) (offsite link - local copy - downloadable - will open in a new window)
	Motorola Semi - RF Device Data Volume 1 (1998 version) (offsite link - local copy - downloadable - will open in a new window)
	Motorola Semi - RF Device Data Volume 2 (1998 version) (offsite link - local copy - downloadable - will open in a new window)
	Motorola CMOS Data Book DL131/D Rev 3 (1991) 6.9MB PDF This is a scan of the actual data book on Motorola’s entire MC14000 series CMOS products.

There are some more good articles at http://www.ad5x.com/articles.htm and at http://www.ad5x.com/presentations.htm.

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This web page created 20-Aug-2004

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.