[amsat-bb] is it really QRP making the difference
jdanehy at cinci.rr.com
Wed Dec 17 09:20:56 PST 2008
After 4 months of working the satellites I have the following observation . . . .
I have QSLed close to 300 stations with great response (thanks for confirming close to 200 Grid Squares) . . . most but not all of those QSOs were North American stations . . . . many (but not all) QSLs indicate the type of antenna that was used . . . my statistics show that about 2 out of 3 are using some compromise antenna . . . definition of compromise antenna : Elk, Arrow, Eggbeater, Vertical. They are compromised compared to a Yagi or Helix antenna. Some of the compromised antennas are further impaired by being used indoors.
I have often worked K9CIS on either FO 29 or AO 7 when Frank was running milliwatts and I had an armchair copy on CW. He was not running compromised antennas. FM mode is the mode of choice for most. Those using FM must realize that there is a difference on how FM receivers work. The strongest signal captures the discriminator and comes out on top compared to a competing signal. That does not occur on SSB or CW. Frank, K9CIS and Mike, K9QHO further assisted me when I got on in August with my use of a dual polarity yagi. . .this type of antenna mitigates the constantly changing polarity heard by those using linear (vertical or horizontal) polarity. . .
Many of those compromised antenna users also use QRP power levels ( 5 watts or less). . . . when I got back into satellite operating from a 30 year hiatus, I noted the advertising for the Arrow and its use with an HT (QRP) rig. That was certainly novel and interesting from my 56 years of operating sometimes with stacked yagis on HF and VHF. . . My receiving antenna for satellites has 14 db of gain and dual polarity . . . well 13 db of gain is equivalent to a multiplier factor of 10 for 10 db and double that to 20 for the extra 3 db. A friend of mine has used the Elk and the Arrow. He could not carry on a cross town QSO on 435 mhz using the Elk so he sent it back.
I often make QSOs into France, UK, Netherlands and Belgium on AO 7 using my antennas at an elevation of 1 or 2 degrees. I can hear very well with these antennas. Something that a compromised antenna can not do. [ transponder satellites] AO7 , FO29, VO52. . . turn on a preamp and it gets even better for the transponder operator . . . you do not use a preamp on an HT . . .
With 5 watts (QRP) on FM and a 10 db transmitting antenna my ERP is 50 watts . . . . and an HT @ 2 or 3 maybe 5 watts to a compromised antenna maybe is lucky to get 6 db gain (a factor of 4) . . . for an ERP of 8 to 10 watts and linear polarity (another compromise) which can reduce the ERP during a pass by a factor of 3 db (half) . . . cutting the HT's operator's power to 4 or 5 watts . . . compare that to my 50 watts ERP ( 5 watt station ) with no compromise antennas used both on FM and Transponder satellites to the HT operator . . you will see that it is not QRP levels but antenna efficiency and effectiveness that is the BIG difference . . . QRP operating refers to the power not to the antennas being used . . . I think folks need to reflect on what QRP operating is compared to QRP and compromised antennas . . .
Using an HT is OK but do not expect it to compare to the same 5 watt power level and a set of yagis . . . 5 watts is still 5 watts for either station . . . the difference is the antennas. . . . . yes it is novel and good PR to see HT users use the satellites . . . . . reality is something else . . .
A pair of yagis with dual polarity (not linear polarity) and ACCURATE TRACKING is still another advantage that is compromised by the hand held antenna . . . I have seen operators wave the antenna and twist it around . . . well it works . . . the yagi operator using elevation and azimuth rotors can set his antennas to the correct positions within a couple of degrees . . . . that is another advantage over a compromised antenna . . . .
yes there is a lot of passion by the Davids out there who want to outdo the Goliaths . . . that is human nature . . . if both are running 5 watts ; the increased gain , tracking and superior polarity all add up to grabbing the FM receiver in the satellite and shutting out the less advantaged station running the same power but with inferior antennas . . .it is the antennas not the 5 watt QRP that makes the difference . . .
Probably 20 % of the FM users have the superior antennas compared to those with compromised antennas . . . . so often the compromised antenna user feels good and being able to compete (against other compromised antenna users) for QSOs . . . in the situations where they run into a user who does not have a compromised antennas they should understand the situation for what it is . . . it is not QRP against non QRP it can be the antenna
hearing is another issue . . . i call stations that I want to add to my Grid Square or country total like every one else . . . others do not hear the DX stations i call . . .i can get multiple stations replying to my call . . . others get upset . . . . remember what compromise means = PATIENCE and UNDERSTANDING. . . . thanks for reading , I hope this helps some understand the reality of the situation . . .
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