Re: Question about tuning for doppler and SatPC32
In a message dated 11/20/06 6:35:06 PM Eastern Standard Time, ehekman@cox.net writes:
Since I have found it easy to implement and it makes QSOs much easier to maintain I am curious why computer controlled Doppler correction is not used by all stations. Are there some radios still in use that do not have the capability for computer control?
Ed WB6YTE
Hi Ed....
Just speaking for some of us Luddites, the thrill and challenge of a "pure" QSO, maybe with just CW, is part of the experience. I suppose I could get my computer to run consecutive QSOs, doppler tune, voice track, log, post my log in LOTW etc, but that is not what I enjoy.
My opinion is that "I did it myself" applies to computer "programming," and to satellite operation seperately.
I will reward you on your accomplishments, but reserve the right to set my own goals.
That said...anyone want to try AM through AO-7? hihi
Roger WA1KAT
On Nov 20, 2006, at 7:22 PM, RogerKola@aol.com wrote:
In a message dated 11/20/06 6:35:06 PM Eastern Standard Time, ehekman@cox.net writes:
Since I have found it easy to implement and it makes QSOs much easier to maintain I am curious why computer controlled Doppler correction is not used by all stations. Are there some radios still in use that do not have the capability for computer control?
Ed WB6YTE
Hi Ed....
Just speaking for some of us Luddites, the thrill and challenge of a "pure" QSO, maybe with just CW, is part of the experience. I suppose I could get my computer to run consecutive QSOs, doppler tune, voice track, log, post my log in LOTW etc, but that is not what I enjoy.
My opinion is that "I did it myself" applies to computer "programming," and to satellite operation seperately.
I will reward you on your accomplishments, but reserve the right to set my own goals.
That said...anyone want to try AM through AO-7? hihi
Roger WA1KAT
Roger,
Where do you find the equator crossing times for your Oscarlocator since W1AW doesn't broadcast them any more ;-)
73,
John AA2BN
Where do you find the equator crossing times for your Oscarlocator since W1AW doesn't broadcast them any more ;-)
Very simple, John, just run any tracking program in fast forward, and write it down!!
73, Dave wb6llo@amsat.org Disagree: I learn....
Pulling for P3E...
OM-s As I got so much truely valuable and usable feedback on my hybrid power divider/combiner questions, I now dare to ask the following.
For making circulary polarised yagis one needs to split 'things' over two yagis There are basically two ways to split power A- use a 36 ohm power splitter, often a piece of waveguide with one connector on one end(for the TRX) and two connectors (for the Yagis) on the other end B- use a 70 (75) ohm hybrid power splitter/divider, which has 4 ports, one extra for a terminator. The TRX sees just 50Ohm.
A- and B- are both fine for SPLITTING power. In both cases the TRX sees 50ohm, although there are two 50ohm connected in parallel and the other side of the divider. So both are fine for transmit.
But...... A- Is ONLY a power splitter seen from the transmitter's side, it does present a mis-match as seen from the yagi, so on receive things are less than optimal B- Does work both ways, it presents a nice 50ohm port to the yagi, but the RX signal is split between the RX and the other yagi, so the signal that goes to the RX is 3db down.
Does anybody have a view on how "bad" A- is vs B-?
Have fun Joop, PA1JAV
Joop, If you yous two 75 Ohm 1/4 wavelength sections to make the power divide and another 50 Ohm 1/4 wave section on one antenna to give the 90 degree phase shift it should work just fine. The antennas are 50 ohm. Another solution is to offset one antenna a 1/4 wavelength on the boom from the other when mounting two antennas crossed on the same boom. Hybred is also a solution but be careful of losses on the broad band devices.
Art, KC6UQH ----- Original Message ----- From: "Joop & Tineke Verdoes" joop.verdoes@nameplanet.com To: amsat-bb@amsat.org Sent: Tuesday, November 21, 2006 4:33 AM Subject: [amsat-bb] Relative merits power divider vs power divider/combiner
OM-s As I got so much truely valuable and usable feedback on my hybrid power divider/combiner questions, I now dare to ask the following.
For making circulary polarised yagis one needs to split 'things' over two yagis There are basically two ways to split power A- use a 36 ohm power splitter, often a piece of waveguide with one connector on one end(for the TRX) and two connectors (for the Yagis) on the other end B- use a 70 (75) ohm hybrid power splitter/divider, which has 4 ports, one extra for a terminator. The TRX sees just 50Ohm.
A- and B- are both fine for SPLITTING power. In both cases the TRX sees 50ohm, although there are two 50ohm connected in parallel and the other side of the divider. So both are fine for transmit.
But...... A- Is ONLY a power splitter seen from the transmitter's side, it does present a mis-match as seen from the yagi, so on receive things are less than optimal B- Does work both ways, it presents a nice 50ohm port to the yagi, but the RX signal is split between the RX and the other yagi, so the signal that goes to the RX is 3db down.
Does anybody have a view on how "bad" A- is vs B-?
Have fun Joop, PA1JAV
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
----- Original Message ----- From: "Joop & Tineke Verdoes" joop.verdoes@nameplanet.com To: amsat-bb@amsat.org Sent: Tuesday, November 21, 2006 1:33 PM Subject: [amsat-bb] Relative merits power divider vs power divider/combiner
OM-s As I got so much truely valuable and usable feedback on my hybrid power divider/combiner questions, I now dare to ask the following.
For making circulary polarised yagis one needs to split 'things' over two yagis
Hi Joop, PA1JAV
You need to split the TX power in two equal parts (3 dB) and to generate circular polarization the above equal parts of power must be radiated 90° out of phase by the two yagis. This can be accomplished by mounting the yagis in the same plane over the boom and feeding one yagi with a 90° delay line (1/4 electrical wavelenght long) or mounting the yagis over the same boom with 1/4 wavelenght physical offset and feeding the yagis in phase i.e. with the same lenght of feed lines for both yagis. If you do this the signal that can be received by the two yagis in RX conditions will be circularly polarized as in TX conditions and with the same sense of polarization.
There are basically two ways to split power A- use a 36 ohm power splitter, often a piece of waveguide with one connector on one end(for the TRX) and two connectors (for the Yagis) on the other end
The above A-power splitter has a characteristic impedance of 36 ohm it is a transmission line 1/4 electrical wavelenght long and during TX has the property to transform the 50 ohm impedance of the feed line in to the 25 ohm impedance of two 50 ohm yagis in parallel.
During RX conditions the 36 ohm matching line has the property to transform the 25 ohm impedance of two 50 ohm yagis in parallel in to 50 ohm impedance of the feed line and infact SQR (50 x 25)= 35.36 ohm or about 36 ohm
If the impedances as seen at the end of the above 36 ohm matching line are 50 ohm at one side and 25 ohm at the other side then in TX conditions the available power will be divided by two (3 dB) and 50% of the total power will feed each yagi while in RX conditions the power received by each yagi will be added in phase and applied to the 50 ohm line feeding the RX
By the way in TX condition or in RX condition the SWR of the 50 ohm lines feeding both yagis and the SWR of the main line feeding the TX /RX is 1
Since the 1/4 wavelenght long matching line operates the impedance transformation between 50 to 25 ohm and between 25 to 50 ohm then the SWR inside of it is 50/36 or 36/25 = 1.41 but only inside of it so that the losses of the matching line due to the SWR are negligible
B- use a 70 (75) ohm hybrid power splitter/divider, which has 4 ports, one extra for a terminator. The TRX sees just 50Ohm.
A- and B- are both fine for SPLITTING power. In both cases the TRX sees 50ohm, although there are two 50ohm connected in parallel and the other side of the divider. So both are fine for transmit.
A- and B- are also fine for receiving because the impedance transformations are working in both directions and the performance in TX and RX conditions is the same.
But...... A- Is ONLY a power splitter seen from the transmitter's side, it does present a mis-match as seen from the yagi, so on receive things are less than optimal
Disagree: A- is a 1/4 wavelengt 36 ohm matching line between 50 and 25 ohm. This line as seen from TX to the yagis is a power splitter and if the impedances of the two yagis are 50 ohm then the power flowing to the yagis is splitted in to two equal parts in phase and than radiated while no power is dissipated in the 50 ohm termination at 4
The same 36 ohm matching line as seen in RX conditions from the yagis is a combiner because the received power from each yagi is available at the 25 ohm point and is added in phase by impedance transformation in to the 50 ohm feed line going to RX and so the performance of the power splitter/combiner is the same in TX and in RX conditions.
B- Does work both ways, it presents a nice 50ohm port to the yagi, but the RX signal is split between the RX and the other yagi, so the signal that goes to the RX is 3db down.
Disagree: Here is a drawing of the hibrid ring power divider/combiner in which all 6 sections are 1/4 electrical wavelenght long lines made of 75 ohm coax cable 3 /°\ / \ / \ / \ 4 50 ohm 2 °| |°----////----| | | | | 1 °\ / \ / \ / /
Connect a TX in 2 with a 50 ohm yagi in 1 and the other yagi in 3 In TX conditions if the TX power is 100 watt the power appearing at 1 and 3 will be 50 watt in theory with the same phase and the power in 4 is zero.
Connect a RX in 2 with the same 50 ohm yagi in 1 and the other yagi in 3 If the lenght of the lines feeding both yagis are the same lenght and if they are connected to the same hot side of the driving elements then the received signals available from both yagis are applied to 1 and 3 with the same phase and their sum appear in 2 in phase without any 3 dB loss while the power at 4 is zero (or 0 volt)
The SWR = 1 in to all outside 50 ohm lines connecting the yagis to the hybrid and the hybrid to TX/RX while the SWR inside the ring of the hybrid is 75/50= 1.5
Does anybody have a view on how "bad" A- is vs B-?
Method A can be better than method B or vice versa depending on the specific use we need
Have fun Joop, PA1JAV
We already discussed this matter on BB the 26 may 2006 with messages titled " Power Dividers fo X-Yagis" wich are available from the AMSAT-BB archives but at that time the theme was centered on the comparison between hibrid-rings and Wilkinson divider/combiners.
Best 73" de
i8CVS Domenico
participants (6)
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Dave Guimont
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i8cvs
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John Zaruba Jr
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Joop & Tineke Verdoes
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kc6uqh
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RogerKola@aol.com