HFU HF Underground
Technical Topics => The RF Workbench => Topic started by: Stretchyman on December 12, 2019, 1852 UTC
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Just to guage the interest or otherwise....
I'm toying with the idea of designing an ssb driver (5W) to drive the monster linears using the BLF188XR.
I'm aiming for decent quality, no ne602 rubbish.
8 pole filter and -50dBc for carrier, however b/w will be 7.5KHz for nice w-i-d-e audio.
Your thoughts please.
:)
Str.
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How are you planning to generate the SSB, phasing or filtering?
+-RH
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Thanks for the post...
So....Mixing initially.
AD831 and 8 pole 7.5K wide filter etc.
However I'm happy to experiment.
As with any product it will be the simplest and best implementation I can find.
I'm open to suggestions!
Regards
Stretchy.
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7.5khz is overkill for "thump thump" and SSTV 8)
~
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I disagree. I'll take all the bandwidth I can get, up to 15KHz.
+-RH
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I know redhat and several other ops disagree with me on this, but... IMHO any transmitted spectral content over about +/- 6 kHz (if you have an SIO 555 signal), and down to about +/-3 kHz for the average reception quality of a pirate, is wasted energy. :P
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The filters, if I use that method are +/-3.75 8 pole and very reasonably priced.
Most A.M. Rx filters are 6KHz, hence my decision.
Str.
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I know redhat and several other ops disagree with me on this, but... IMHO any transmitted spectral content over about +/- 6 kHz (if you have an SIO 555 signal), and down to about +/-3 kHz for the average reception quality of a pirate, is wasted energy
Of Course I'm more Esoteric but I'm in the Belief that You should transmit the best quality signal / audio for your listeners. I think it makes for a more enjoyable broadcast I run 20hz -10khz audio but I have the ability to run full 20 - 20khz If the listener has the ability to hear full bandwidth audio I'm sure they would like to. If not they can decide on how much filtering is needed. I have many reports sent to me that included an audio clip of the show and most are very enjoyable to listen to. So Why Not if you can.
BTW... AM is the standard.. SSB is a compromise.. The key is the signal not be fatiguing
tAC
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I've looked at some description of how phasing SSB works and can't see how it could work very well if at all for music. Are the descriptions too simple or what?
~
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Phasing SSB is nothing more than a pair of balanced modulator fed with I and Q carriers and modulating signals that are 90 degrees out of phase. The audio is passed through two all-pass networks to derive the required phase delay. It used to be that the carriers were derived by passing the RF carrier through a 90 degree phase shift network. This doesn't work over a wide range of frequencies, and it better solved today by using DDS chips with sine and cosine outputs. The audio phase delay networks are the only thing that really limits your audio bandwidth, and implementations up to 20 KHz are not uncommon.
I echo the sentiments of AC above. I set the transmission bandwidth for my enjoyment. The listener can choose how much they want to hear.
+-RH
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Yes AC, I've got A.M. done but I'd still like to put out a product to drive the BLR family, makes for a very simple KW SSB setup and I can already use a 5W AM. Tx to drive them for A.M.
I've still to sell anything to any Ham, altho' they are not my priority I wouldn't mind another market to generate more sales.
Regards.
Stretchy.