| November, 2007 |  |
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Satellite Shorts from All Over [AMSAT]
- Drew, KO4MA, AMSAT VP Operations reminds AO-51 users that its time to again submit your mode requests for the month of October. Please submit them to ao51-modes@amsat.org as soon as possible.
- Norm Fusaro, W3IZ, ARRL Assistant Manager, Membership & Volunteer Programs Department wrote this week, “After review, ARRL will permit contacts through the ISS (Earth - ISS - Earth) to be counted towards satellite endorsement for WAS and DXCC. This applies to contacts made via the onboard repeater equipment provided that the equipment does not hold and re-transmit information. Contacts with the ISS do not receive any award credit. Further information will be available on the LoTW website.” See: http://www.arrl.org/lotw/
- Masa, JN1GKZ has an FO-29 Operation Schedule page at: http://www.ne.jp/asahi/m-arai/gkz/satinfo/fo29e.htm
Three Packet Satellites Available on 145.825 MHz [AMSAT]
Bob, WB4APR reminds satellite packet operators of the opportunity of up to 25 passes per day for 2-way keyboard communications with simple packet equipment on 145.825 MHz uplink and downlink.
The 145.825 MHz frequency includes ARISS aboard the ISS, ANDE and PCSAT-1 operating at 1200 baud. Recently GO-32 became available on 435.225 MHz for 9600 baud communications.
APRS Igate Packet gateway stations copying these three packet digipeater satellites on 145.825 feed to the two web pages:
http://www.ariss.net
http://pcsat.aprs.org
For additional information regarding the GO-32 435.225 MHz 9600 baud operation see:
http://www.ew.usna.edu/~bruninga/GO32-ops.html
F8ZS Silent Key [AMSAT]
It is with sadness that I must inform our AMSAT colleagues, of the passing away of Jean Edmond Gruau F8ZS, President of Radio Amateur Club de l’Espace and Honorary President of AMSAT-France.
Jean was the father of ARSENE radioamateur mini satellite, launched in May, 1993.
He retired a few years ago from his position as Inspecteur General of the French space agency (CNES) that he contributed to create as well as the European Space Center in Kourou, French Guyana.
Jean F8ZS was a very kind man with always a lot of good stories to tell to his visiting friends about his large experience in radio transmissions and preventive failure security in space industry.
73 de Bernard, F6BVP, AMSAT France founding President
“THE DOCTOR IS IN” [THE ARRL LETTER]
This week, ARRL Letter readers are in luck! The ARRL’s very own Doctor, author of the popular QST column “The Doctor Is IN,” answers a question from his mailbag:
Question – Ray Fritts, KA8SYX, of Jacksonville, Florida, asks: If a piece of coaxial cable has a specified loss figure in dB per 100 feet at a given frequency, does that mean that the loss in a different length of the same cable that is a fraction of 100 feet long is the same fraction of loss?
For example, I have a type of coax that has a loss of 6 dB per 100 feet at 150 MHz. I have a 15 foot length I want to use as a feed line for my 2 meter mobile SSB transceiver. Does that mean that my feed line would have a loss of about 0.9 dB, not including SWR and connector insertion? I am particularly interested in the loss in received signal. Is my math correct, or is there a different method to determine the amount of signal lost in a coaxial cable when the length is different from that for which the published loss figures are expressed?
The Doctor Answers – Your calculations are right on. That’s all there is to it. But do keep in mind just a few potential pitfalls:
Published cable loss data is for new cable. If used indoors in a non-hostile environment, it will stay close to new for many years. If the jacket allows moisture or moisture vapor to penetrate, it can degrade from subsequent corrosion. I have been amazed to find that the copper in some old cables that have been used outdoors has turned black from corrosion, and likely is no longer acting like a shield at all.
You are correct that the loss increases with an SWR higher than 1:1. For your receive case, keep in mind that the SWR is determined by the input impedance of the receiver — not the antenna impedance. Sometimes receivers aligned for minimum noise figure do not have an impedance of 50 Ohms. Check your receiver specs.
Do you have a question or a problem? Send your questions to doctor@arrl.org; or to “The Doctor,” ARRL, 225 Main St, Newington, CT 06111 (no phone calls, please).
| November, 2007 | |
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