November 2003

THE SQUELCH BURST

We have had our meeting room changed several times over the past four months (four out of four actually) and we have had another change for the November meeting. Fortunately, we have again obtained the use of the Mural Room at the Stamford Senior Center

(Stamford Government Center). A nice room with the convenience of a nearby kitchen. I am trying to obtain this room as a regular meeting room.

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T-Hunting on 121.5

There was an interesting article on ELT’s (Emergency Locator Beacons) in the October issue of CQ magazine. The FCC has authorized the sale of PLB’s (Personal Locator Beacons) on July 1st, 2003. These are belt worn units for hikers etc. to be used only in extreme emergencies. They will broadcast on 406MHz for initial location and identification and will also broadcast on 121.5 MHz for local search and rescue operations.

The broadcasts on 406MHz will be used for identification purposes as all units are required to be registered. The initial use of EPIRB and ELT units resulted in 97% accidental activations. The new units will alert an MCC ( Mission Control Center) which will notify NOAA which in turn can telephone the owners emergency phone number to determine if a real emergency exists.

The 121.5 beacon is close enough to ham frequencies so that ham t-hunt equipment can be used with a proper receiver.

The Santa Barbara Radio Club has been doing 121.5 hunts for 14 years. They have a web site at www.sbarc.com  

WA1VUU

November 2003

ASK ELMER

Dear Elmer: I know that you have written on this subject before, but

would like to see a review on the matter of frequency counters and how to adjust them to WWV.

Signed , 39 and counting.

Dear 39,

It is important to periodically calibrate your equipment, whether it be your radios or a piece of test equipment. Both scientific and industrial laboratories maintain a rigid calibration schedule for their equipment to guarantee the accuracy of their tests and products. Many years ago, the industrialized countries of the world agreed upon a series of physical standards, so that something measured in one country will be the same in another. Our government agency is the National Institute of Standards and Technology under the Department of Commerce. Among the standards they maintain is the standard of Time, which by a simple bit of arithmetic becomes the Standard of Frequency. One of the many services they provide is the broadcast of a radio signal derived from the National Frequency Standard, housed in Fort Collins, Colorado. The frequencies that are broadcast are 60 KHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. The accuracy that is maintained is better than 1 part in 10^-14. This is far more accurate than you would need in practice unless you were manufacturing frequency or time standards. Even though the transmitted frequencies are so accurate, propagation effects degrade its accuracy by the time it reaches our location. For short term measurements, the local accuracy is probably somewhat better than 1 part in 10^-7. This translates to an error in the order of 3 Hz at 30 MHz. For measurements made on amateur radio equipment, this accuracy should be more than sufficient. Unless you have a laboratory grade frequency counter with a precision oven controlled reference oscillator, most counters are only accurate to 1 part in 10^-6 or 30 Hz at 30 MHz.

In order to calibrate your counter, you require a AM radio capable of tuning to 20 MHz. It in itself need not be accurate, as long as it receives the signal from WWV. Method 1: Connect an antenna consisting a short piece of wire to your counters reference oscillator output, and it should be near the AM radio’s antenna jack. You should be able to detect the harmonic of the counter’s reference oscillator in the radio at 20 MHz. At the same time the radio is receiving a signal from WWV. There will be a audio beat note present due to the mixing of the two signals in the receiver. Tune the frequency set trimmer in the counter to minimize the tone of the beat note. Ideally you want to hear a beat note of less than 1 Hz, which will sound like a popping noise in the loudspeaker or headphones. Counting the beats per minute will indicate how close you are to WWV. If there is no output connecter for the counters internal reference, it may be possible to pick up a signal by placing the counter close to the radio.

Method 2: In the event that your counter does not use a 1, 5 or 10 MHz internal reference, but operates from a 3.579545 MHz color burst crystal, an indirect method must be used. This requires an AM-SSB transceiver capable of receiving on 20 MHz and transmitting on 21 MHz and a dummy load. The radio will be used as a transfer oscillator. Set the power output of the radio to its lowest setting. Set the radio on SSB and tune the radio to 20 MHz. Zero beat the radio with WWV. Note the difference between the dial reading and the actual zero beat. Set the radio to 21.0 MHz, and loose couple the counter to the output of the radio near the dummy load. This may require some playing to obtain a large enough signal to operate the counter. Make sure the offset measured at 20 MHz multiplied by 1.05 is added to the frequency setting. The 1.05 makes up the frequency difference between 20 and 21 MHz. Switch the radio to AM and key the transmitter. Adjust your counters reference oscillator until the counter reads 20.000 00 MHz. With care, this calibration method should get you to within 10 Hz of the actual frequency.

A note of general caution. If your counter is not able to resolve 10 or 100 Hz, the trying to calibrate it to this precision may be a waste of your time. A basic rule of thumb is to calibrate your system to 1/10 its resolution.

Ordinarily, a standards laboratory tracks station WWVB at 60 KHz using specially designed receivers to obtain accuracies approaching that of the US Frequency Standard itself and can take several days.

I hope this gave you some insight into the rigors of calibrating frequency counters. Good luck on doing yours.

73,

Elmer

Send your questions to “ASK ELMER”, c/o Marv  N1AWJ,  e-mail .

 November 2003

EMPIRE SLOW SPEED NET

Join the Empire Slow Speed CW Net every evening on 3590 KHz at 6PM local time. CW speed is between 6 and 8 wpm. A great way to improve your CW proficiency and learn net operation. Joe, W1LUH is one of the rotating Net

YE OLDE JONQUE BOXXX

COMET CX-333, 3 Band Vert., 2M, 220 & 440, Like New, No Tuning Req’d., $ 100. Triplexer for use w/Comet Ant w/Leads $60; Icom T8A HT w/slow charger & 2 extra Batt’s., $150; Radio Shack HTX 242 2m 10/45W Mobile w/o mounting bkt., $85

Call Chris, N1YNO at (203) 359-0570 evenings

ESTATE SALE (N1CML) Yaesu FT-980 HF Xcvr, $475; Yaesu FT 726R 2M all mode Xcvr $325; Yaesu YS-60 SWR-Pwr Mtr, $50; MFJ Versatuner II (300W), $100; Tram Reflectometer, $15; Azden PCS3000 2M Mobile w/o Mic, $25; HP5301 10 MHz Freq Ctr. $25; Eldorado 1615 30 MHz Freq Ctr., $25; AEA PK-88 Packet TNC, $35; Leader LAC 897 2M Transmatch, $20.

Call Marv, N1AWJ, (203) 438-7889 or e-mail 

DIGITRAVLER Personal Navigation System w/ Delorme Street Atlas USA for a laptop computer. Will work with Tiny Track 3. New. $55

Call Bill, KB1IFY, (203) 353-8131 Evenings

DRAKE STATION: TR7 HFxcvr,RV7 remote VFO, PS7 pwr supp, WH7 watt meter, MS7 spkr. Astron RS12A pwr supp, ETO Alpha 76A HF Amp, Nye Viking MB II match box, Nye Viking phone patch, Heathkit SB 610 monitor scope,

Daiwa CN 720 SWR/Power meter. Stan, WA2NRV 914-949-6838

ICOM IC-2AT 2m HT w/Charger, Batty., & SS-32MP micro-min. CTCSS Encoder kit, VGC, $100; Simpson 260 VOM, VGC, $50.

Call Geoff, N1CAT, (203) 966-7444 evenings

HALLICRAFTER SX-28A RECEIVER, recapped, $275. Works good.

Call Joe, N1GWO, (203) 322-4061 Evenings

PARTS GALORE- Xerox 3000 Word Processor (antique) w/transformer,

p/s, etc., connection to Diablo printer. FOR FREE!!! Take it away!

Call Mike, KA1VWP, (203) 838-8089

AOR 1000 XLT, 1000 Channel HH Scanner, 5KHz to 1.3 GHz cont. coverage. Exc. cond. $ 275.

Call Rick, N1LYK, (203) 531-1756

YAESU FT-757 GXII, HF Rig, FP 757 HD Power Supply, FC 757 AT Tuner

and MD 1B8 Desk Mike.

Call George, N1HIX, (203) 357-1879

Mac Laserwriter printer, best offer.

Call Jeanine, KY1Q, (203) 324-6865

FOR PARTS..Olevetti Accounting Machine. FREE!!!!! Take it away!!!

Call Marv, N1AWJ, (203) 438-7889

HD-73 ROTOR w/CONTROL & CABLE, $50; Cushcraft 10-40M Vert. Ant., $15; Heathkit Station Monitor Mod. 614, $50. 2 South Bend 7.5 HP Go-Cart Engines. Call for Info.

Call Irv, N1ATS, 348-3425 or e-mail [email protected]

2M 30W AMPLIFIER, $25; 6M Amplifier, 10W in 150W out, $175: AM6155 2M SSB Amplifier, 8930 Tube based, Cavity Tuned, 400 W Out (not cont. duty) $325.

Call Andy, KA1SLG, (203) 531-9493

MFJ ANTENNA TUNER A-1 Cond. $100; Cushcraft R4 Ant , New, $25; ¼ λ Mag. Mt. Ant., $12; ⅝ λ Mag. Mt. Ant, $15, ⅝ λ Trunk Mt. Ant., $10; Measurements Grid Dip Meter, $25; HP Signal Gen.; $15; Code Pract. Mach., $15

Call Milt, K1DLT, (203) 324-2723

HYGAIN CD 45-II Rotator Control w/cable and manual.

Call Frank, KA1NTG at (203) 655-7378