Carrier on SSB

[Robb]

Thanks Robb. Please enlighten me on your technique using a laser pointer to locate solder joints, if you will?

That method doesn't work on every board made; some use thicker and more opaque material. But all you do is put the radio on its side, pick a cap, and then put the glowing tip of the laser pointer under the cap until the light disappears on the solder side of the board, and then - Bob's your uncle. Just that simple.

 

[sonoma]

if you do not have a laser light a bright small flash light will work. just shine it on the legs of the cap and you can see where it goes through the board to unsolder it. I have one that makes a small beam and it works good when I have trouble finding the legs to unsolder it.

 

[Yeti Communications Ltd]

RV1 and RV2 (carrier balance controls for the balanced modulator ) adjust both for min rf output on ssb with no modulation (on transmit)

both pots have effect so adjust one for min carrier then adjust the other one working back and forward till you see no rf on rf meter..to fine tune it use a receiver listening to the carrier or a scope on the output of the radio for min rf envelope(which is the best way)

unlike 90% of other ssb chassis the cybernet ssb radios use two carrier balance pots to remove the carrier injection on ssb at the balanced modulator (IC1)

if this fails to lower the rf carrier on ssb then suspect the voltage rail cap feeding the balanced modulator ..you will always have a carrier at mico watts level as no balanced modulator will fully remove it but it should not be readable on a external rf watt meter

i am sure the resident troll will have some magical cure for that

 

[Johnno]

RV1 and RV2 (carrier balance controls for the balanced modulator ) adjust both for min rf output on ssb with no modulation (on transmit)

both pots have effect so adjust one for min carrier then adjust the other one working back and forward till you see no rf on rf meter..to fine tune it use a receiver listening to the carrier or a scope on the output of the radio for min rf envelope(which is the best way)

unlike 90% of other ssb chassis the cybernet ssb radios use two carrier balance pots to remove the carrier injection on ssb at the balanced modulator (IC1)

if this fails to lower the rf carrier on ssb then suspect the voltage rail cap feeding the balanced modulator ..you will always have a carrier at mico watts level as no balanced modulator will fully remove it but it should not be readable on a external rf watt meter

i am sure the resident troll will have some magical cure for that

View attachment 22812

Hey Dave, RV1 and RV2 don't even make it move one iota!

 

[nomadradio]

It's incredibly useful to have a frequency counter in line with the coax when this happens.

I'll guess that your carrier is not anywhere near the channel frequency you selected. The final transistor has a bad habit of becoming an oscillator, producing its own signal at a random frequency, not on your channel.

The radio was built with a 2SC1307 final transistor. We have found that replacing it with the somewhat more-modern 2SC1969 can make the final stage unstable, especially if the SSB bias is turned too high.

Loose ground screws around the edge of the circuit board can do this, too.

73

 

[Yeti Communications Ltd]

Hey Dave, RV1 and RV2 don't even make it move one iota!

not dave its mike

recap it then ..you should have about 8v/(+/-0.5v) at pin 9 of ic1 (pin6 side of R20)
then yes recap as this is a main rail feed however you said the rest of that radio works fine and this rail feeds all modes

nomad is quite right in the rf final however the crystal filter in these radios do have a habit of breaking down also skewing the bandpass of the offset this would be evidenced by the other sideband leaking thru and yes a carrier ..as noted before he (johnno) said it was working fine in other modes so i dont suspect a vco/pll issue as nomad asked about (freq counter)
but if the offset oscillators are way off..and i mean WAY off yes a carrier will be on tx on ssb but also will show as a carrier on receive..another common problem with the cybernet chassis
the dual board cybernet chassis is a pig to work on due to the dry joint and crap board connectors between the sandwiched boards

end of day this chassis is older than arctic ice and well over due for a preventive maintenance recap..some thing that should be done before trying to fault find..remember to recheck rv1/rv2 if you do any recapping
have a couple of these in the cupboard and always liked them could not tell if yours is a 18 channel aussie version or 40 channel usa version..maybe one of these guys can source you a 40 channel switch if 18 channel

ok i have to go do paid work..laters and good luck

 

[Johnno]

It's incredibly useful to have a frequency counter in line with the coax when this happens.

I'll guess that your carrier is not anywhere near the channel frequency you selected. The final transistor has a bad habit of becoming an oscillator, producing its own signal at a random frequency, not on your channel.

The radio was built with a 2SC1307 final transistor. We have found that replacing it with the somewhat more-modern 2SC1969 can make the final stage unstable, especially if the SSB bias is turned too high.

Loose ground screws around the edge of the circuit board can do this, too.

73

The carrier is on 28.34XXXX on both USB and LSB

 

[Johnno]

not dave its mike

recap it then ..you should have about 8v/(+/-0.5v) at pin 9 of ic1 (pin6 side of R20)
then yes recap as this is a main rail feed however you said the rest of that radio works fine and this rail feeds all modes

nomad is quite right in the rf final however the crystal filter in these radios do have a habit of breaking down also skewing the bandpass of the offset this would be evidenced by the other sideband leaking thru and yes a carrier ..as noted before he (johnno) said it was working fine in other modes so i dont suspect a vco/pll issue as nomad asked about (freq counter)
but if the offset oscillators are way off..and i mean WAY off yes a carrier will be on tx on ssb but also will show as a carrier on receive..another common problem with the cybernet chassis
the dual board cybernet chassis is a pig to work on due to the dry joint and crap board connectors between the sandwiched boards

end of day this chassis is older than arctic ice and well over due for a preventive maintenance recap..some thing that should be done before trying to fault find..remember to recheck rv1/rv2 if you do any recapping
have a couple of these in the cupboard and always liked them could not tell if yours is a 18 channel aussie version or 40 channel usa version..maybe one of these guys can source you a 40 channel switch if 18 channel

ok i have to go do paid work..laters and good luck

Yikes, sorry Mike! It is Dave over on the Charlie Tango forum and TM1, isn't it? OK, a recap it is, it's an 18 aussie but wants to be a 40
.
A 40 switch would be nice, hard to find here.
Thanks for all the help guys, I'll be back with more noobish questions after recap

 

[Yeti Communications Ltd]

Yikes, sorry Mike! It is Dave over on the Charlie Tango forum and TM1, isn't it? OK, a recap it is, it's an 18 aussie but wants to be a 40
.
A 40 switch would be nice, hard to find here.
Thanks for all the help guys, I'll be back with more noobish questions after recap

not on those fourms..
no mr dave has his own account here and no idea if he has accounts at either of those two forums

 

[MidlandMax]

Hello, I just bought a second hand handheld Albrecht AE 2990 AFS and it seems to be the same problem with a carrier on LSB and USB. Any ideas what is wrong?

 

[BC Coyote]

Carrier on sideband (either mode) is usually caused by issues with the balanced modulator and/or associated components. It may be as simple as finding the right VR and adjusting for zero carrier on sideband, or there may be problems with circuit. Not familiar with that particular radio though..........

 

[MidlandMax]

Carrier on sideband (either mode) is usually caused by issues with the balanced modulator and/or associated components. It may be as simple as finding the right VR and adjusting for zero carrier on sideband, or there may be problems with circuit. Not familiar with that particular radio though..........

Thanks a lot

 

[MidlandMax]

Thanks a lot

Maybe one day we will get contact when propagations are good

Best//21OK777

 

[BC Coyote]

Maybe one day we will get contact when propagations are good

That would be wonderful ! Hopefully conditions will pick up again......they haven't been good compared to a month or two ago when we had Europe in every morning here. Will listen out for you on 555.

 

[Klondike Mike]

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