Login or register:
Login:
Password:
Register!


Imageserver Favorite:


Portfolio Galleries:
Animals
Architecture
Flowers
Landscape
People
Wildlife

Recent Subjects:
Landout
5-inch sky robot
Vacuum printing
e-bike
Farnsworth Fusor


Search:


Resources:
ImageServer

Friends:
Jon Sullivan
Mark Blair


New Articles:

Southern California Glider Landout Database
Soaring
5-Inch Sky Robot
FDM in Vacuum
Gin
Books
Hacktastic e-bike
Farnsworth Fusor
Land Anchor
Turchickentato
Bowmaking
Custom Discovery Roof Rack
August, 2012 - Sierra Backpacking
July 22nd, 2012 - Hiking in Santa Barbara
July 15th, 2012 - Valley of Fire
May 5th, 2012 - Afton Canyon
April 28th, 2012 - Devils Playground
Alpine Tripod
Convict Creek Trail
January 2012 - Mustangs
January 3rd, 2012 - Heart Lake
August 7th, 2011 - Kelso Dunes
August 5th, 2011 - Lundy Canyon Hike
August 2011, Mammoth Archery
Birds in the garden
June 4th, 2011 - San Gorgonio
May 29th, 2011 - Sequoia National Forest
April 23rd, 2011 - Living Desert
April 2nd, 2011 - Death Valley
March 8th, 2011 - Mountain Palm Springs
February 13th, 2011 - Iron Smelt
Blacksmithing
November 13th, 2010 - Mojave
October, 2010 - Mammoth
Android
September, 2010 - Mammoth
September, 2010 - Duck Lake Trail Backpacking
Red
Iron bloom forging
August 28th, 2010 - Mt. San Jacinto
OSM Import: US Designated Wilderness
July 25th, 2010 - Mojave Mustangs
July 17th, 2010 - Mojave Exploration
Bloomery furnace iron smelting
Open Street Map: Mojave Project
June 13th, 2010 - Mojave
June 6th, 2010 - El Cajon Trails
Wolf Mountain Sanctuary
Carrizo Gorge
March 28th, 2010 - Salton Sea
March 21st, 2010 - South Main Divide
March 13th, 2010 - Anza Borrego Wildflowers
March 7th, 2010 - CSULB Japanese Garden
February 2010 - Mammoth
GeoRSS
AISlib
OpenStreetMap
Dakota and Asha Celebrate Christmas, 2009
November 21st, 2009 - Mojave Road
November 14th, 2009 - Anza Borrego
Exploring The East Mojave: The Afton Canyon Area
Broken flex plate
Remote Image Serving
Astro/night photography in Inyo National Forest
Wild Mustang Sightings
RSS
September 26th, 2009 - Night Photography In Frazier Park
Whiskey
Brandy
August 15th, 2009 - Catalina dive trip
Astrophotography
Sensornet
January 24th, 2009 - Mojave Exploration
July 2008 Mammoth Vacation
AIS
President Barack Obama!
Rachel Maddow
Big Geek
Barack Obama
April 12th, 2008 - Wildflowers and Landmarks
My Grandfather's Alfa Romeo Spider
March 8th, 2008 - Carrizo Plain
Bridge To Nowhere
High Availability
October 20th, 2007 - Big Bear Camping
October 22nd, 2007 - Fire
Scottish Highlands, Aug 7th, 2006
Scottish Highlands, Aug 6th, 2006
August 5th, 2007 - Duck Lake Trail
May 26th, 2007 - Kelso Dunes
Culloden Battlefield, Aug 5th, 2006
May 20th, 2006 - Irwindale Renaissance Faire
Edinburgh, Aug 4th, 2006
The Clifs of Moher, Aug 3rd, 2006
The Burren, Aug 2nd, 2006
Bunratty Castle, Aug 1st, 2006
May 5th, 2007 - Mojave
Truck Audio/Data Network
2007 - Master Bath Remodel
Centrum: Exit
The Ring of Kerry, Jul 31st, 2006
Nikon D200
Victory in 2006!
Blarney and Killarney, Jul 30th, 2006
Dublin and Cork, Jul 29th, 2006
Dublin, Jul 27th & 28th, 2006
Married!
What Can I Do?
April 30th, 2006 - Anza Borrego
New desktop: Intel 805 D
Macro Photography
Jan 7th and 14th, 2006 - Hiking
Whiting Ranch Hiking
Engaged!
Digital Photography with Linux
September 5th, 2005 - Living Desert
August 19th, 2005 - Mammoth
Hiking and Photography
July 30th, 2005 - Tucker Wildlife Sanctuary
Nikon D70
Death, Fright and Photography
Mmmmmm Eggs
MythTV
Inova T4
May 14th, 2005 - Red Rock
April 2nd, 2005 - Death Valley
Count Every Vote Act of 2005
Image Archiving
Linear Logic ScanGuage
Gentoo Linux
November 6, 2004 - Mojave
Super Tuesday, 2004
John Kerry
Kayaking
Irish Stew
ImageServer
Ireland, 2004
Canon A80 Camera
Jul 25, 2004 - Death Valley
Chronic Hiccups
May 4th, 2004
Landscaping - My Front Slope
Stump Pullin' Yeeee Haw!
Feb 22nd, 2004
Feb 16th, 2004
PostgreSQL Logfile Analysis
Spam
Mountains? Desert? Jan 30th, 2004
Jan 28th, 2004
Encryption
Ceiling Cargo Basket
Front Bumper Version 2
Asha
Exide Orbitals
Land Rover Valve Jobs
Spirits
The Matrix: Revolutions
Halloween 2003
Greg Davis CDL Linkage
Ouzo
Democracy
Mom's Turkey Gravy
Grandma's Guacamole
Top Nodes
Julian Pie Company
DeCSS
The KB1DIG 2-meter Halo Antenna
Incomming searches
Gardening is hard!
Aug 13th, 2003
SQL and Perl
Cancun 2003
Jul 9th, 2003
Aprs intelegence
Jun 17th, 2003
Some People's Comments
Dakota is a silly dog
The Matrix: Reloaded
Chris' Stage Bottle Harness
April 23rd, 2003
Cracked Radiator!
Black Wednesday
DVD Burning Under Linux
My Satellite Phone
Wind!
My Near-Death Experience
Laser Cannon Revival
Front Bumper, Version 2
SpamAssassin
The Critters
Dakota
Milton
KPC 3 Plus and HTX-252
My House
Moving, moving moving...
Mobile 1
Portola Hills
New new house
Suse Linux
Database images
In Truck Dr. Pepper
My Favorite Toilet
Kelso Dunes
Desert Trips
Ifulmuh
Late Thoughts: Dr. Pepper Cooler
265/75-R16 Tires on a DII
Linux
George W. Bush
Rants
Driving
Reservations
Horses Sep 14 2002
Obsession
August 17th Yukon Dives
Less notifications
My Custom Front Bumper
Bracketless, Renamable Links
Discreet Winch
Welding
Jul 28 2002 Day Trip
My Firewall
Jedi Group, my T1 and money
A Bumperless Discovery!
My Custom Rear Bumper
Vanessa's 24th Birthday
Jun 30th Dive to Long Beach Canyon
PHP/PostgreSQL String Quoting
Tonsillectomy, Uvulaectomy and Turbinite Reduction
Searching functionality
240 Watt CO2 Laser Cannon
My Workspace
Dr. Pepper
The Tulsa Rib Company
The quality of hard disks these days
Email notification of articles
Email notification of comments
erikburrows.com source code
User Bios
User Preferences
Login feature
Renisance Faire Jun 9, 2002
Computers hate me, and it is mutual.
Star Wars Sucks!
Horses, Jun 1, 2002
Land Rover Mileage
Insomnia, Robin goes evil.
100 Watt Diode Laser Test Firing 1
Amateur Radio
The Matrix
2001: A Space Odyssey
TDI Deco Class
Horses, Apr 30, 2002
APRS
Movies
Blackbird
My Truck Batteries
My Truck
Vasquez Rocks
The Zope Bible
PSK31
Mojave Apr-12-2002
100 Watt Diode Laser
The New www.erikburrows.com
Hunter the Kitty
Horses
Geeks
Yukon May-13-2001
Computers
Matts Desert Pics
Mojave Feb-10-2001
Mojave Apr-01-2001
Programming Languages
Ironage Jul-4-2001
Mojave Jan-27-2001
Ironage Feb-03-2001
Mojave Jun-09-2001
SCUBA
Jedi Group
KPC 3 Plus and HTX-252   -   2002/12/09Viewed 108 times this month, last update: 2004/11/27


I've been asked how I wired up my Radio Shack HTX-252 2 meter FM HAM radio to my Kantronics KPC 3+ TNC.

Actually, I couldn't find out how to do it either, so I kind of had to figure it out on my own. The hard part is that the HTX-252 doesn't detect PTT as most radios do, by shorting PTT to ground. The HTX-252 detects PTT by shorting one of the mic pins to an isolated ground. The specifics of this mechanism are out on the 'net somewhere... I couldn't find it again. Sorry.
The basics are this:
  1. Connect the center pin of the HTX-252's audio out jack to pin 5 of the KPC 3+ DB9 connector
  2. Connect the ground of the HTX-252's audio out jack to pin 6 of the KPC 3+ DB9 connector
  3. Connect pin 1 of the HTX-252's DIN-8 microphone jack through a 5% 2200 k ohm resistor to pin 3 of the KPC 3+ DB9 connector
  4. Also connect pin 1 of the HTX-252's DIN-8 microphone jack through a 104k capacitor to pin 1 of the KPC 3+ DB9 connector.
  5. Open up the KPC 3+ and jumper the J9 center pin to the 'HT' pin.
  6. Optionally, connect pin 2 of the KPC 3+ to pin 2 of a DB9 connector, and pin 6 of the KPC 3+ to pin 5 of the DB9 connector to connect up to a GPS for position data, to be read from the GPSPORT of the KPC 3+
Here's my hand-made diagram:

Click to enlarge

Note: If I were to setup another APRS station, I would not use the Radio Shack HTX-252. It's signal is very noisy, and it's recive quality could be much better. Also, it's display uses quite a bit of juice, so, if I were to do it again, I would use one of the 'data radios' available, which operate at a set frequency and mode, and have no display. (Unless of course, this other radio may be used manually in an emergency.)

Update: 2004/09/01
Last week, I noticed that every time my radio transmitted a packet, my FM sterio would fuzz. Worse, when I was listening to my CD player via one of the fake-tape doohickeys, it would Fuzz too. Then I noticed that while working in my garage, the FM sterio on my workshelf woulf fuzz. It seems the HTX-252's noise gets worse with age. I've had to turn off my transmitter, since I'm certainly not licensed to transmit into the FM broadcast band!

Update: 2004/09/27
I need to take back the above. The HTX-252 did not die. It was another casualty of the Death Valley washboard roads. The antenna wire nut got vibrated right off! Yesterday I screwed it back on, and all is well.

Update: 2004/11/17
William Avery e-mailed me with lots of informational links about the HTX-252:
The HTX-252 Service Manual which you can order from Radio Shack is:
Cat# 12276358, MANUAL SERVICE 19-1127 ; NP Part # MS1901127

This was listed on a partial parts list at:
http://support.radioshack.com/support_electronics/doc59/59612.htm
from the official HTX-252 web-support site:
http://support.radioshack.com/support_electronics/59611.htm
"Product: Amateur Radios
Question: How do I get a schematic and/or pinouts for my radio?
Answer: For schematics or pinout information, you would need to reference the Service Manual for the radio. Service manuals can be ordered by contacting either your local RadioShack store or by calling RadioShack.com at 800-241-8742"

The second quote is from a more up-to-date-site at:
http://support.radioshack.com//support_tutorials/communications/67164.htm#A2

Additional Support is listed on:
http://support.radioshack.com/productinfo/DocumentResults.asp?sku_id=19-1127&Name=Ham+and+Marine+Radios&Reuse=N

The HTX-252 Microphone Pinout is at:
http://support.radioshack.com//support_tutorials/communications/67164.htm#190-1127a

The commercial unit called "RASCAL GLX" with a HTX-252 cable, which is for TNC/sound card use, is available at:
http://www.packetradio.com/cgi-bin/shopper.exe?preadd=action&key=CBL_HTX252

There is a site which sells Ham Manuals, including the HTX-252 (#19, for $16.00), at:
http://www.hamradiomanuals.com/view_manual.php?m=190
A free source of manuals is at:
http://www.hamanuals.com/miscmans.html , where the Owners Manual is at:
http://www.hamanuals.com/MMans/HTX252MAN.pdf
And the 50 page Service Manual (for Albrecht AE-540, which equals R.S. HTX-252):
http://www.hamanuals.com/MMans/HTX252SVC.pdf

Finally, the Microphone Manual is available separately from the Service Manual at:
http://www.hamanuals.com/MMans/HTX252MIC.pdf

There is a site which has a few related comments on HTX-252 modifications:
http://www.mods.dk/view.php?ModelId=582

There is a neat description of one man's efforts to make an interface, described in a newsletter called Smoke Signals [ http://www.qsl.net/k3smd/smok1001.pdf ], and the last article by Don Munson, W4GFQ, called "HOMEBREWING, A LOST ART?", has a link to another effort by Stephen A. Smith, WA8MLF, at: http://members.aol.com/wa8lmf/ham/tonekeyer.htm with 3 designs documented there.

Comments:
KD7PLU / trooper (2003-01-23): Yes- KPC3+ and HTX-252 was a great idea on paper. But the HTX-252 radios are not worth the effort. I was dumb enough to buy six of them on close-out for 99 bucks each. Two of them worked, three didn't. Alinco just came out with an inexpensive TNC-integrated radio, and the Vertex VX-150 with a 4-pin to standard Spkr/Mic adapter makes an ideal APRS radio if you're usually close to some kind of Wide node.

Rich/N2ROW (2004-01-14): Can you email me the mic wiring for the htx-252. Thanks velezrd@fdny.nyc.gov

k1lwi (2004-10-12): looking for a schematic diagram htx 252 can you help 73 wen k1lwi e mail k1lwi@aol.com

Erik (2004-10-13): Sorry, I don't know where you could get the full diagram for the htx 252.

anonymous (2005-09-12): My HTX-252 transmitts OK, but the receiving side seems to have a problem with the squelch opening. I get NO audio on regular signals, but a strong repeater in the local area open the squelch OK. Is there a control someplace inside the unit to rectify this condition?
w6ors@arrl.com

Erik (2005-09-13): W6ORS, you're saying your squelch is not opening enough? Maybe it's just the potentiometer, which can be replaced, if you're careful. Are you using this radio for APRS? If so, you can probably just short the squelch open, and let the TNC pick out the signals itself.

N0YXV (2007-10-17): APRS no longer uses 'WIDE' for digi's. To reduce QRM APRS now uses WIDEn-N in place of WIDE. To use WIDEn-N effectively you would replace the N's with a number between 1 and 3. (i.e. WIDE3-3). In place of RELAY APRS now uses WIDE1-1. Mobile paths are usually set with two settings WIDE1-1, WIDE2-1. I live in a sparcly populated APRS area and even a path as small as WIDE2-2 easily covers 200-300 miles.

Brian KJ4AGA (2008-11-21): Do you know where I could find another microphone for the htx252?


Thanks
Brian South
KJ4AGA

KB1GVR (2008-12-21): I've had my HTX-252 on APRS/PKT wired to an MFJ-1274 since 2001 and got the schematics from my local RS dealer.

BJ452 (2009-02-25): IS anyone still interested in the 252 - I bought one for $40, soldered a spare wire into the microphone plug to allow both Mic and TNC use. The Mic line has 5v so I let the PTT line form TNC ground it through a 2.2K resistor wiht a .02uf cap to decouple - works a treat for may packet stuff.

Don Keyes (2009-02-25): Will some please help!!! I have the PK-232 and HTX-252 radio to use for packet. Is there a mod or wiring for this? Don N7OTO email: siriusconnection@q.com

Joe N4SP (2010-04-12): Approximatly what levl should the audio out be set to to run into the APRS TNC?

Erik (2010-04-13): Joe,
I've found that the KPC isn't too picky. Some experimentation may be worthwhile, but I found "somewhere in the middle" works well. If you live in a high traffic area, just watch the "Rx" light on the KPC as you manipulate the volume knob on your radio.

Bill (2011-01-23): i have a problem with my htx232 when i add offsets to my radio
then i transmit an e shows after i try to save in memory

Paul (2012-11-15): I have an HTX-252 and a KPC-9612+. I'm trying connect the two, but I don't have any resistors or capacitors on hand. Will it brick the radio if I wire it up like you have it and don't use any resistors or capacitors?

Thanks, 73
Paul KJ4YOJ

Erik (2012-11-15): Paul, I don't know if building this circuit without the capacitor and resistor would fry your radio or TNC, but I'm pretty sure the circuit would not work, so it's probably not worth trying. I suggest going down to your local Radio Shack to get the proper components.

See also: APRS

permalink

Email me!


Erik Griffin Burrows and ErikBurrows.com are not responsible for any damage or loss caused by viewing this site, or actions taken as a result of reading any part of this site. Articles and comments on this site should not be taken as legal, medical, scientific, engineering, botanical, dietary or any other kind of professional direction. This site is not affiliated with any business institution.

You get the idea. This site is just another big pile of misinformed, uneducated, unsolicited opinion, and should be judged as no more truthful or accurate as anything else on the internet.

Don't Panic!