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eHam Forums => Misc => Topic started by: KB9WQJ on March 06, 2012, 06:53:58 PM



Title: USB on 7.230 40 meters?
Post by: KB9WQJ on March 06, 2012, 06:53:58 PM
Am I missing something?  For 2 nights in a row now I have heard a group at 7.230 USB (rather than LSB) .... what's up with that?  I've been away from ham radio a wee bit and just got some wire back up and listening around....it took me aminute to figure out why I could't zero beat with them...it worked once I flipped from LSB to USB.  Thanks & 73.


Title: RE: USB on 7.230 40 meters?
Post by: WW3QB on March 06, 2012, 06:58:37 PM
I don't know about this specific group but there are groups using surplus military radios that only do USB on 40m. I don't think any other radio service uses LSB.


Title: RE: USB on 7.230 40 meters?
Post by: K2OWK on March 06, 2012, 09:48:10 PM
As a ham it is legal to use upper or lower sideband on 7.230. Upper or lower sideband can also be used on any ham band allowing single sideband use except the 60 meter band where only upper sideband can be used per FCC rules. With that said, the ham community by has set up a system for single sideband use that recommendeds that lower sideband be used on the lower frequencies of 160 thru 40 meters, and upper sideband on frequencies of 20 meters and higher. This is not a rule just a recommendation that is followed by most hams, so the fellows operating on 7.230 MHZ upper sideband are not breaking any rules, just not operating as recommended.

73s

K2OWK


Title: RE: USB on 7.230 40 meters?
Post by: KB9WQJ on March 07, 2012, 04:47:47 AM
  Yes, I'm aware it's legal...just unconventional.  Thanks.


Title: RE: USB on 7.230 40 meters?
Post by: K0OD on March 07, 2012, 05:29:58 AM
As previously stated that's a regular group of military radio fans... definitely a law-abiding bunch.

They often use USB on 60 meters but their usual base on 5371.5 has been overrun what-with the new rules having gone into effect Monday. All five channels have been covered with CW, PSK31 plus the usual USB, and modes and frequencies not allowed under the very complex rules.  A mess but gradually getting better.


Title: RE: USB on 7.230 40 meters?
Post by: K9EID on March 09, 2012, 08:05:34 AM
The 7.230 Upper Sideband signals are indeed a group of interesting guys that restore and operate surplus gear from WW 2.  Most of that gear was built to operate on USB.   Join the group and learn more about some of this great old equipment.   You will see many of them communicating with each other at hamfests with their huge old
'handie talkies'.   

Bob Heil, K9EID


Title: RE: USB on 7.230 40 meters?
Post by: W3HKK on March 18, 2012, 12:00:52 PM
Yep.  Unconventional.  And while there are those who only operate within the GAAP (generally accepted amateur practices)  there are those who revel in doing the opposite.

You can join them or  choose to ignore them, whichever the case may be. 

Just like intentional interference, growling at the clowns only makes them more motived to create their form of mayhem.  Gritting your teeth  and ignoring them is the best way.


Title: RE: USB on 7.230 40 meters?
Post by: G3RZP on March 19, 2012, 03:27:22 AM
When did the military start using SSB? I haven't seen anything military with SSB earlier than the mid to late 1950s: interestingly, that early stuff generally had both sidebands available, although some of that was to allow ISB working.


Title: RE: USB on 7.230 40 meters?
Post by: KB4QAA on March 19, 2012, 02:11:03 PM
When did the military start using SSB? I haven't seen anything military with SSB earlier than the mid to late 1950s: interestingly, that early stuff generally had both sidebands available, although some of that was to allow ISB working.
In the US, the military didn't start with SSB until the mid 50's.  USAF General Curtis LeMay "Bomb 'em back to the stone age", was an active ham and asked Art Collins of Collins Radio to collaborate with SSB experiments. 

They fitted up a USAF plane with both AM and USB radios and made and extensive (if not world circling) tour comparing the two modes on both military and ham frequencies.  SSB won hands down.  This was widely covered in ham magazines of the time.  The rest is history.


Title: RE: USB on 7.230 40 meters?
Post by: W8JX on March 19, 2012, 02:22:45 PM
As I recall NASA used 5.5ghz SSB to talk to first men on moon in 1969. Bet that was one expensive radio on LEM.


Title: RE: USB on 7.230 40 meters?
Post by: WW1I on July 09, 2013, 11:36:58 AM
Yep.  Unconventional.  And while there are those who only operate within the GAAP (generally accepted amateur practices)  there are those who revel in doing the opposite.

You can join them or  choose to ignore them, whichever the case may be. 

Just like intentional interference, growling at the clowns only makes them more motived to create their form of mayhem.  Gritting your teeth  and ignoring them is the best way.
For crying out loud, what a bunch of nonsense.  All military radios only operate on USB.  All aviation radios only operate on upper side band.  There is no regulation that does not allow the use of this equipment on the ham bands and those that operate USB on these bands don't interfere with anyone.   


Title: RE: USB on 7.230 40 meters?
Post by: WW1I on July 09, 2013, 12:00:43 PM
By the way, I fly a Boeing that has two Rockwell-Collins HF radios.  These radios operate anywhere in the HF spectrum on AM or USB.  Many folks like to talk to airplanes or military stations, not to mention those that use surp equipment.  I guess you would just make up your own regulations and ban all these radios and operators? 


Title: RE: USB on 7.230 40 meters?
Post by: KE3WD on July 09, 2013, 04:40:53 PM
...All aviation radios only operate on upper side band...

Aircraft Band is AM. 


Title: RE: USB on 7.230 40 meters?
Post by: N3HFS on July 09, 2013, 05:25:34 PM
...All aviation radios only operate on upper side band...

Aircraft Band is AM.  
VHF Air communications are AM.  
HF Air communications are USB.

Here's a source:  http://www.hamuniverse.com/aerofreq.html


Title: RE: USB on 7.230 40 meters?
Post by: G3RZP on July 10, 2013, 03:02:08 AM
The early HF SSB aviation radios had USB, LSB and AM. By about 1975, it was all USB,  the same as the maritime services - who only ever had LSB on the very few ISB transmitters.

There was one version of a manpack mil radio that had LSB and USB, but there weren't many of them made: the USB only version was the most common.


Title: RE: USB on 7.230 40 meters?
Post by: WB2EOD on July 11, 2013, 04:46:19 PM

The convention of using LSB on 160, 80 and 40 and USB on everything else goes back to the early days of SSB.
Within the transmitter, the signal was generated as upper sideband in the 8-9 MHz range.
One or more mixers then brought the signal to the correct frequency.
On 20 meters, for example, the 8.3 MHz USB signal might be mixed with a 6MHz signal, the output would be the SUM of the 2 signals or 14.3 MHz upper sideband.
On the other hand for 80 meters, the same 8.3MHz USB signal would be mixed with with a 12 MHz signal and the DIFFERENCE would be 3.7MHz.  Since we are 'subtracting', the original USB signal would be inverted to LOWER sideband. 
I have heard this explanation more than once and it does seem technically (if not historically) sound.

73
WB2EOD


Title: RE: USB on 7.230 40 meters?
Post by: G3RZP on July 12, 2013, 03:23:38 AM
I've found references in the late 1940's/early 1950's to using a 5 MHz USB generator with a 9 MHz VFO: this gave LSB on 80 and USB on 20.


Title: RE: USB on 7.230 40 meters?
Post by: W9GB on July 12, 2013, 06:50:02 AM
Quote from: KB9WQJ
For 2 nights in a row now I have heard a group at 7.230 USB (rather than LSB)
Correct.  I sometimes listen to this frequency of surplus military radio collectors, when they have technical discussions of various surplus, military/gov't radios (many that only operate USB or ISB).  Most of these surplus US military/state department/government radios (TransWorld, Collins/Rockwell, etc.) only have USB (no LSB mode).

BTW, THE 60 meter (5 MHz band) is also, USB -- just like the NTIA stations (who use commercial/military radio equip.), we share those 5 channels with.

When I was a Novice in early 1970s,
I use to listen to an AM group based in Ohio at 7240 kHz, they were entertaining.


Title: RE: USB on 7.230 40 meters?
Post by: N2EY on July 12, 2013, 10:24:19 AM
The convention of using LSB on 160, 80 and 40 and USB on everything else goes back to the early days of SSB.

That part is true.

Within the transmitter, the signal was generated as upper sideband in the 8-9 MHz range.
One or more mixers then brought the signal to the correct frequency.
On 20 meters, for example, the 8.3 MHz USB signal might be mixed with a 6MHz signal, the output would be the SUM of the 2 signals or 14.3 MHz upper sideband.

That was a common arrangement.


On the other hand for 80 meters, the same 8.3MHz USB signal would be mixed with with a 12 MHz signal and the DIFFERENCE would be 3.7MHz.  Since we are 'subtracting', the original USB signal would be inverted to LOWER sideband. 

I don't know any transmitter that did it that way. Not one.

I have heard this explanation more than once and it does seem technically (if not historically) sound.

But it's not what happened at all.

First off, it should be remembered the late 1940s the bands, subbands and licenses in the USA were somewhat different than today. In those days, the US ham bands were 80/75, 40, 20, 11 and 10 meters. 160 had been a popular ham band before WW2 but had been taken over by LORAN and we got it back in bits and pieces over several decades. 11 was given to hams as a sort of compensation but was shared with industrial, scientific and medical machines. 30, 17, 15, and 12 meters were years in the future.

On top of all that, 40 meters was all-CW, no phone operation allowed. So US 'phone hams focused on 75 and 20 - which were narrower back then.

The origin of the LSB/USB convention is what G3RZP posted: the use of an SSB generator in the 5 MHz range and a VFO or crystal oscillator in the 9 MHz range. This was done in the late 1940s. With such a system, the sideband inverts on 75 but not on 20. Both bands covered.

The original filter method used an LC filter down around 20 kHz, and needed two conversions to get to 5 MHz, followed by a third to get to the ham band. Lots of complexity but it worked. Crystal filters of the necessary characteristics did not exist yet, and mechanical filters were only good up to 500 kHz or so.

The phasing method came to the rescue, with the development of the Dome audio phase shift network. For some reason, it became popular to generate the SSB at 9 MHz and use a 5-6 MHz VFO to convert to 75 or 20. This scheme worked on other bands too - mix 9 MHz SSB with the third harmonic of the VFO and get on 40 or 10, mix with the second harmonic and get on 15. Commercial exciters such as the Central Electronics 10A, 10B and 20A appeared as early as 1952 using this method.

With the use of a 9 MHz SSB generator and 5 MHz VFO, the sideband DOES NOT invert when switching bands! But with a phasing-type generator, this is no problem because a simple phase reversal in one audio channel does the trick. A DPDT switch is all it takes.

There is a persistent urban legend that the USB/LSB convention came from the use of a 9 MHz SSB generator and 5 MHz VFO to get 75 and 20. This is a myth, because sideband inversion doesn't work that way. You only get inversion if the local oscillator is higher in frequency than both the input and output signals.

73 de Jim, N2EY



Title: RE: USB on 7.230 40 meters?
Post by: G3RZP on July 13, 2013, 04:20:40 AM
Always puzzled me why third method wasn't more popular - I suspect because the complexity was more expensive than a crystal filter.


Title: RE: USB on 7.230 40 meters?
Post by: W4OP on July 13, 2013, 02:14:46 PM
With the use of a 9 MHz SSB generator and 5 MHz VFO, the sideband DOES NOT invert when switching bands! But with a phasing-type generator, this is no problem because a simple phase reversal in one audio channel does the trick. A DPDT switch is all it takes.

There is a persistent urban legend that the USB/LSB convention came from the use of a 9 MHz SSB generator and 5 MHz VFO to get 75 and 20. This is a myth, because sideband inversion doesn't work that way. You only get inversion if the local oscillator is higher in frequency than both the input and output signals.

73 de Jim, N2EY


Thanks Jim- I  have gotten tired of dispelling this myth over the years.

Dale W4OP


Title: RE: USB on 7.230 40 meters?
Post by: G3RZP on July 13, 2013, 03:17:31 PM
One problem to watch with 9 MHz SSB  minus 5 MHz VFO is the spur of 4 times VFO minus two times SSB. i.e.,  20 to 22 MHz minus 18 MHz gives a spur covering 2 to 4 MHz, and falls in band. This really needs a balanced mixer to get rid of this 6th order spur.


Title: RE: USB on 7.230 40 meters?
Post by: K9MHZ on July 27, 2013, 09:37:57 AM
...All aviation radios only operate on upper side band...

Aircraft Band is AM.  


KE3WD....Maybe an example of doing your homework before correcting someone.  The voice portion of the VHF aircraft band is AM.  That's ATC, AIRINC, CTAF, company freqs, etc.  HF aircraft freqs are USB.  In the civilian world, it's used primarily over water for ATC, and in the military it's the same as well as some dedicated command and control freqs.  All USB.  When you check in with San Francisco or Gander Radio for example, you'll be assigned a primary and secondary HF USB freq, and then receive a SELCAL check with your aircraft's unique SELCAL address.  The freq that you dial into the control head is the freq of that sideband....NOT the 1.5 KHz offset deal that we have to do on 60 meters.  That's because everyone's on USB, so it would be a pointless step to compute an offset.

Today however, SATCOM and especially CPDLC are taking over in a big way.  CPDLC is near-real time ATC via data linking with the controlling agency.  The communication of that data linking goes through a hierarchy of onboard radio gear....VHF comm, then HF comm, then satellites....and will burst data when it has success, since using satellites is expensive.  This all relegates voice HF USB and SELCAL to a backup status, so listening to an HF USB ATC freq today would sound pretty dead....mostly HF SELCAL checks.  Those who still do get ATC via HF USB  are operating older gear, or are not otherwise equipped with modern gear.

 


Title: RE: USB on 7.230 40 meters?
Post by: K9MHZ on July 27, 2013, 09:40:30 AM
...All aviation radios only operate on upper side band...

Aircraft Band is AM.  


KE3WD....Maybe an example of doing your homework before correcting someone.  The voice portion of the VHF aircraft band is AM.  That's ATC, AIRINC, CTAF, company freqs, etc.  HF aircraft freqs are USB.  In the civilian world, it's used primarily over water for ATC, and in the military it's the same as well as some dedicated command and control freqs.  All USB.  When you check in with San Francisco or Gander Radio for example, you'll be assigned a primary and secondary HF USB freq, and then receive a SELCAL check with your aircraft's unique SELCAL address.  The freq that you dial into the control head is the freq of that sideband....NOT the 1.5 KHz offset deal that we have to do on 60 meters.  That's because everyone's on USB, so it would be a pointless step to compute an offset.

Today however, SATCOM and especially CPDLC are taking over in a big way.  CPDLC is near-real time ATC via data linking with the controlling agency.  The communication of that data linking goes through a hierarchy of onboard radio gear....VHF comm, then HF comm, then satellites....and will burst data when it has success, since using satellites is expensive.  This all relegates voice HF USB and SELCAL to a backup status, so listening to an HF USB ATC freq today would sound pretty dead....mostly HF SELCAL checks.  Those who still do get ATC via HF USB  are operating older aircraft, or are not otherwise equipped with modern gear.
 


Title: RE: USB on 7.230 40 meters?
Post by: G3RZP on July 27, 2013, 10:57:19 AM
While the older Non Directional Beacons (NDB) in the 200 to 1600 kHz or so band (mostly below about 600kHz) are disappearing fast and many airline pilots will tell you that it is so long since they had to do a 'hold' pattern using NDBs that they have forgotten how!