NQ4S McLean, Virginia, USA
Fairfax County
ITU Zone: 8 - CQ Zone: 5 - Grid: FM18jw

Distance to the DC area repeaters

Use this page to figure out how far you are from various repeaters in the Washington, DC area and what direction to point towards to reach these repeaters.

Enter your position

You must have the lattitude and longitude coordinates of your position to use this calculator. A site for looking up coordinates for a given address is available here. When entering the values, note that one arc second is equal to about 101 feet, so it doesn't really help to go past whole second values.

If you know your coordines in decimal (such as -77.1674 longitude) then enter that value for degrees and leave minutes and seconds empty or set to '0'.

You can also try one of these predefined locations:

  Degrees (°)  Minutes (')  Seconds (")  Direction
Lattitude  North South
Longitude  West East

Your grid location: (undefined)

Distance and direction to area repeaters

2-meter band
Repeater Freq (Mhz) Tone Miles KM Direction Club Location Lattitude Longitude
W3ETX 145.110-     (unknown) Washington, DC  
WB4MJF 145.150-     (maybe AARC) Arlington, VA  
W3DOS 145.190-     Department of State ARC Washington, DC  
N3EZD 145.230- 110.9   Central MD ARC New Carrollton, MD  
W3RCN 145.250-     Rock Creek ARA Rockville, MD  
N4NW 145.270- 103.5       SARA Stafford County, VA 38°27'53"N 77°27'15"W
K3YGG 145.290-     NIH RAC Bethesda, MD  
KF4QQP 145.310- 77.0   Dulles ARG Dulles Airport, VA  
KB3BOI 145.350- 156.7   (need research) Waldorf, MD  
WA3DVO 145.430-     (unknown) Washington, DC  
N3GKZ 145.450- 156.7   (need research) Rockville, MD  
WB4MJF 145.470-     Arlington ARC Arlington, VA  
W3EAX 145.490-     Univ of MD ARA College Park, MD  
KF4JPC 146.625-     Arlington Radio PSC Arlington, VA  
K4US 146.655-         MVARC Alexandria, VA 38°48'26"N 77°3'59"W
K4HTA 146.685-     Vienna Wireless Society Vienna, VA  
WA4TXE 146.700-     (unknown) Sterling, VA  
WA3DZD 146.760-     MD FM Association Washington, DC  
K4KXK 146.790-         No Va FM Assn Fairfax, VA 38°50'42"N 77°18'35"W
WA3NAN 146.835-         Goddard ARC Greenbelt, MD 38°59'33"N 76°50'50"W
K3GXF 146.880-     (need research) Greenbelt, MD  
KF4QQP 146.910-     (unknown) Tysons Corner, VA  
KV3B 146.955-     (need research) Rockville, MD  
W4OVH 146.970- 100.0       OVH Manassas, VA 38°47'2"N 77°30'29"W
K3VOA 147.045+         VoA ARC Washington, DC 38°53'15"N 77°0'58"W
KA3LAO 147.180+ 156.7   (need research) Silver Spring, MD  
WB5MMB 147.210+     (unknown) Vienna, VA  
WB3GXW 147.225+ 156.7   (need research) Silver Spring, MD  
W4IY 147.240+         WWRC Lakeridge, VA 38°41'16"N 77°17'53"W *
K4IWF 147.270+     (individual?) Germantown, MD  
WA4TSC 147.300+ 146.2       SVARC Bluemont, VA 39°6'40"N 77°50'4"W *
W4HFH 147.315+     (unknown) Alexandria, VA  
W4NFR 147.345+ 167.9   (unknown) Quantico, VA  
N3AGB 147.360+     (unknown) Washington, DC  
 
1.25-meter band
Repeater Freq (Mhz) Tone Miles KM Direction Club Location Lattitude Longitude
W4YHD 224.100-         No Va FM Assn Fairfax, VA 38°50'42"N 77°18'35"W
 
70-centimeter band
Repeater Freq (Mhz) Tone Miles KM Direction Club Location Lattitude Longitude
WA4TXE 442.100+   (need research) Sterling, VA  
N3EGO 442.150+   (need research) Bowie, MD  
W4OVH 442.200+   (need research) Manassas, VA  
WB3IUT 442.450+   (need research) Indian Head, MD  
WA3WZF 442.500+   (need research) Laurel, MD  
N3UEZ 442.550+ 100.0   (need research) Washington, DC  
N8BOR 442.650+ 156.7   (need research) Washington, DC  
KV3B 442.750+   (need research) Rockville, MD  
N4LXI 443.000+   (need research) Herndon, VA  
N8BOR 443.100+ 100.0   (need research) Dale City, VA  
N3EAE 443.400+ 107.2   (need research) Germantown, MD  
FM4FI 443.500+ 156.7   (need research) Tysons Corner, VA  
K3SMD 443.700+   (need research) Waldorf, MD  
WA3YOO 443.900+   (need research) Rockville, MD  
W3YTW 444.100+ 114.8   (need research) Washington, DC  
WB4MJF 444.150+   (need research) Arlington, VA  
KV3S 444.200+   (need research) Germantown, MD  
KF4LWJ 444.300+   (need research) Falls Church, VA  
K4HR 444.450+ 79.7   (need research) Stafford, VA  
WA3TAI 444.500+   (need research) Accokeek, MD  
K4AF 444.550+ 88.5   (need research) Arlington, VA  
W4HFH 444.600+ 107.2   (need research) Alexandria, VA  
WA3GPC 444.700+   (need research) Bowie, MD  
N4KOU 444.850+   (need research) Vienna, VA  
W4IY 444.900+   (need research) Woodbridge, VA  
KA3RQR 447.025- 100.0   (need research) Tysons Corner, VA  
WB4UNB 447.425-   (need research) Falls Church, VA  
WA3KOK 447.775-   (need research) Bull Run Mtn, VA  
N3LDM 447.825- 131.4   (need research) Washington, DC  
K3Ygg 447.925-   (need research) Bethesda, MD  
N3QEM 447.975-   (need research) Quantico, VA  
K4HTA 448.375-   (need research) Fairfax, VA  
W3ETX 448.575-   (need research) Washington, DC  
KD4DSX 448.625-   (need research) Arlington, VA  
WA3TOL 448.675-   (need research) Lorton, VA  
KC3VO 448.875-   (need research) Washington, DC  
W8HNT 449.325- 79.7   (need research) Arlington, VA  
WA4TSC 449.925- 146.2   (need research) Bluemont, VA  
WA3KOK 449.975- 107.2   (need research) Washington, DC  

Note: When one frequency is listed it is the output (your receive) frequency. The '+' or '-' following the frequency is the offset direction. Offsets are the standard amount of 600KHz for 2-meter band, 1.6Mhz for 1.25-meter band, and 5MHz for 70-cm band. If the frequency is followed by a 's', then it is a simplex frequency. If two frequencies are given, then the repeater uses non-standard offset and the second frequency is the input (your transmit) frequency.

* = Estimated position based on city

Abbreviations:
   ARA = Amateur Radio Association
   ARC = Amateur Radio Club
   ARG = Amateur Radio Group
   PSC = Public Service Club

How this was done

This page was done using JavaScript for the calculations. Originally, I scrounged the far corners of the Internet to find formulas for calculating the distance and heading between two coordinate pairs. The formula for finding the distance between two points was found here. The formula for finding the heading from one point to another was found here. Later, while reading in the ARRL Operating Manual (7th edition, paperback page 15-4) I found the two formulas sitting right together. Even better is that the heading formula in the Operating Manual is much better than the one I originally used.

A variety of techniques were used for finding the locations of repeaters and sample points. Where an address was known, that address was put into the GeoCode locator service, which yielded the lattitude and longitude. Coordinates for other sites were found using the Tiger Map Server. For some repeaters, all I had was a city name to go by, so these locations are only good to within a few miles.

If anyone has good location information for repeaters and notable ground points, or would care to double check points using a GPS unit, I like to be updated.

Any suggestions for improvements may be sent to me by E-Mail.

Formulas

To save you time sorting through all the JavaScript code, here are the formulas used for calculating distance and direction. Both lattitude and longitude are expressed in radians.

Distance

lng_dif = lng_a - lng_b
arc_dist = arccos(sin(lat_a) x sin(lat_b) + cos(lat_a) x cos(lat_b) x cos(lng_dif))

Direction (new formula)

lng_dif = lng_a - lng_b
arc_dist (from above)
bearing = arccos((sin(lat_b) - sin(lat_a) x cos(arc_dist)) / (cos(lat_a) x sin(arc_dist))

Direction (old formula)

a = sin((lat_b - lat_a) / 2)2 + cos(lat_a) x cos(lat_b) x sin((lng_b - lng_a) / 2)2
d = 2 x arctan2(a1/2, (1 - a)1/2)
Direction = arccos(sin(lat_b) - sin(lat_a) x cos(d)) / (sin(d) * cos(lat_b))


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This page developed by Delbert K. Matlock, NQ4S.

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