И защо ме чуват с QRP?
Публикувано: 18 авг 2008, 13:16
По една или друга причина напоследък поизоставих QRP-то тъй като ми беше предоставен временно 100-ватов FT890 (tnx LZ1YE) и не ми дава сърце да предавам /QRP и същевременно ..FT890!
Както и да е, подготвих си трансмач, защото така и не се разбрах по всички обхвати с Windoma, стегнах си малък манипулатор от поляризовано реле (РП) и полека стягам новото QRP - да съм подготвен за "бедния" период без подарени радиа (hi). Междувременно, за да се подкрепя морално усилено чета сайтовете със съответната абревиатура и тук намерих едно добро материалче, с което да отговоря на въпроса-заглавие, често задаван ми и на 3764. Там напоследък LZ2JR си прави експерименти с ЕЛЕКРАФТ-а с мощности до 15-на вата , а покрай него и аз изпробвах минималната мощност на FT-то - около 2 вата. И в двата случая получавахме добри рапорти и пак някои "неопитни" притежатели на акции от тази честота изразяваха удивление - затова не е чудно и недоверието на по новите радиолюбители към малките мощности. Следващия текст е на английски, но той не е толкова важен - достатъчен е поглед на таблиците за силата на сигналите в приемника при различни мощности, и всичко ти става "математически" ясно!
"QRP: A Philosophy or Simple Mathematics?
About 100 watts RF output is the prevailing standard for today's HF transceivers. "QRP" operation is defined by its enthusiasts as RF output of 5 watts or less. An even more dedicated group of experimenters prefer "QRPp" activity with outputs of less than 1 watt. You may be intrigued by the philosophy and camaraderie of the QRP community or you may just want to take a small, lightweight rig on vacation trips. Either way, there are some basics about decibels, RF power output and the RST system useful to understand.
The effectiveness of today's QRP communicating is made possible especially by prevailing standards in receiver circuit design in virtually all HF transceivers. That's why S-5 signals on the meter can seem like "599 " to the ear .
Keep these math facts in mind ...
1. One "S-unit" (on a meter / not by ear) consists of a 6dB increase or decrease in received signal strength.
2. Transmit power must be increased 4 times (400%) to achieve a received signal strength increase of one S-unit.
3. Conversely, lowering power to 25% results in a received signal strength reduction of just one S-unit.
4. Decibels over S-9: a 10 dB increase in received signal strength requires a tenfold increase in transmit power!
How might your 3 watt signal stack up against your main station
with a linear running about 500 watts, getting
you believable "10 over S9" reports? Look at the numbers:
Transmit Power S-Meter Report
500 watts S9 + 10dB
50 watts S9
12.5 watts S8
3.125 watts S7
(remember: + 10 dB over S-9needs x10 RF power, and you lose only 1 S-unit when again
reducing power to 1/4!)
Let's say DX conditions are good, and a 500 watt signal earns
consistent S-8 meter reports from DX. What happens with QRP?
Transmit Power S-Meter Report
500 watts S8
125 watts S7 (power reduced to 1/4)
31.25 watts S6 (power reduced to 1/4)
7.8 watts S5 (power reduced to 1/4)
1.95 watts S4 (power reduced to 1/4)
These examples illustrate one point: if high-power stations are getting excellent reports along a given propagation path, simple math shows that 2-4 watt stations can expect fair to good RST reports, unless the receiving operator is unable or unwilling to work anything but "armchair copy." These examples presume comparable antennas. In fact, the S-unit gap can be even closer between a QRP station with an excellent antenna and the QRO station with mediocre antenna.
TRY SOME CONTESTS! Here's a fun way to find out quickly just how well your QRP-transceiver with a reasonable antenna really works! Join in any of the popular weekend operating contests. Just answer the CQ's of all those "big gun" stations anxious for contacts. If you are answered on the first or second try by a contest operator and you experience little or no problem in confirming contest exchange information, you can say to yourself: "This radio really WORKS!" Then, start calling your
own CQ's with both new confidence and patience!"
Както и да е, подготвих си трансмач, защото така и не се разбрах по всички обхвати с Windoma, стегнах си малък манипулатор от поляризовано реле (РП) и полека стягам новото QRP - да съм подготвен за "бедния" период без подарени радиа (hi). Междувременно, за да се подкрепя морално усилено чета сайтовете със съответната абревиатура и тук намерих едно добро материалче, с което да отговоря на въпроса-заглавие, често задаван ми и на 3764. Там напоследък LZ2JR си прави експерименти с ЕЛЕКРАФТ-а с мощности до 15-на вата , а покрай него и аз изпробвах минималната мощност на FT-то - около 2 вата. И в двата случая получавахме добри рапорти и пак някои "неопитни" притежатели на акции от тази честота изразяваха удивление - затова не е чудно и недоверието на по новите радиолюбители към малките мощности. Следващия текст е на английски, но той не е толкова важен - достатъчен е поглед на таблиците за силата на сигналите в приемника при различни мощности, и всичко ти става "математически" ясно!
"QRP: A Philosophy or Simple Mathematics?
About 100 watts RF output is the prevailing standard for today's HF transceivers. "QRP" operation is defined by its enthusiasts as RF output of 5 watts or less. An even more dedicated group of experimenters prefer "QRPp" activity with outputs of less than 1 watt. You may be intrigued by the philosophy and camaraderie of the QRP community or you may just want to take a small, lightweight rig on vacation trips. Either way, there are some basics about decibels, RF power output and the RST system useful to understand.
The effectiveness of today's QRP communicating is made possible especially by prevailing standards in receiver circuit design in virtually all HF transceivers. That's why S-5 signals on the meter can seem like "599 " to the ear .
Keep these math facts in mind ...
1. One "S-unit" (on a meter / not by ear) consists of a 6dB increase or decrease in received signal strength.
2. Transmit power must be increased 4 times (400%) to achieve a received signal strength increase of one S-unit.
3. Conversely, lowering power to 25% results in a received signal strength reduction of just one S-unit.
4. Decibels over S-9: a 10 dB increase in received signal strength requires a tenfold increase in transmit power!
How might your 3 watt signal stack up against your main station
with a linear running about 500 watts, getting
you believable "10 over S9" reports? Look at the numbers:
Transmit Power S-Meter Report
500 watts S9 + 10dB
50 watts S9
12.5 watts S8
3.125 watts S7
(remember: + 10 dB over S-9needs x10 RF power, and you lose only 1 S-unit when again
reducing power to 1/4!)
Let's say DX conditions are good, and a 500 watt signal earns
consistent S-8 meter reports from DX. What happens with QRP?
Transmit Power S-Meter Report
500 watts S8
125 watts S7 (power reduced to 1/4)
31.25 watts S6 (power reduced to 1/4)
7.8 watts S5 (power reduced to 1/4)
1.95 watts S4 (power reduced to 1/4)
These examples illustrate one point: if high-power stations are getting excellent reports along a given propagation path, simple math shows that 2-4 watt stations can expect fair to good RST reports, unless the receiving operator is unable or unwilling to work anything but "armchair copy." These examples presume comparable antennas. In fact, the S-unit gap can be even closer between a QRP station with an excellent antenna and the QRO station with mediocre antenna.
TRY SOME CONTESTS! Here's a fun way to find out quickly just how well your QRP-transceiver with a reasonable antenna really works! Join in any of the popular weekend operating contests. Just answer the CQ's of all those "big gun" stations anxious for contacts. If you are answered on the first or second try by a contest operator and you experience little or no problem in confirming contest exchange information, you can say to yourself: "This radio really WORKS!" Then, start calling your
own CQ's with both new confidence and patience!"