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148GTL high dead key, no modulation
- Thread starter MrExtreme
- Start date
@Robalo - thanks for sharing this...
This is just an idea,
When you do vids like this - it may help us to see your problem by not just viewing the meters - they do help yes, but we need to hear what you're hearing..
Remember this is radio - you're missing a "Key" component - the Audio...
I see your carrier, and the "Mod" drops but not completely...at least you didn't key long enough for us to see the Mod meters' needle settle down somewhere...
We need to "hear" - not just "see" what you're up against - so put a Monitor Radio up in the shot somewhere, and show us what you find - use the Monitor radios clarifier to help us determine the carrier - if it's merely a centering problem or something more exotic.
Why would this be important?
You're telling us you have a carrier, but we don't know what KIND of carrier you are dealing with...
Some radios - they simply have a Carrier Balance pot problem and just need it either adjusted to center for lowest leakage of carrier, or you have to replace the pot because it's bad.
Just some thoughts...
This is just an idea,
When you do vids like this - it may help us to see your problem by not just viewing the meters - they do help yes, but we need to hear what you're hearing..
Remember this is radio - you're missing a "Key" component - the Audio...
I see your carrier, and the "Mod" drops but not completely...at least you didn't key long enough for us to see the Mod meters' needle settle down somewhere...
We need to "hear" - not just "see" what you're up against - so put a Monitor Radio up in the shot somewhere, and show us what you find - use the Monitor radios clarifier to help us determine the carrier - if it's merely a centering problem or something more exotic.
Why would this be important?
You're telling us you have a carrier, but we don't know what KIND of carrier you are dealing with...
Some radios - they simply have a Carrier Balance pot problem and just need it either adjusted to center for lowest leakage of carrier, or you have to replace the pot because it's bad.
- May help if we see the adjust on the vid and the results - so we can tell you if you have bad parts, coils' turned too far, or your problem is with shielding
Just some thoughts...
Try something. Unplug the mic from the radio and take a small screwdriver and ground pin 5 in the radio against the outer ring to manually key the radio. I want to see if the carrier is present without the mic.
Also key the mic with the mic gain turned all the way down and see what that does.
Also key the mic with the mic gain turned all the way down and see what that does.
Robalo, don't let me distract from what others have you doing.
im coming back into this thread without knowing the updates, and may ask you to do something that has already been tried and eliminated from the list.
i may not have any answers, but maybe doing these tests one more time will lead somewhere anyway.
please don't assume anything because you've tested it already, and actually do the tests i list here. (if you want of course. feel free to ignore me LOL)
1. lift one end of R193 (220 ohm 1 watt) off of the board and measure it.
make sure it tests right around 220 ohms. if ok solder it back in place. if not, replace it.
2. put your meter to DC volts and put the negative probe to PC board ground.
now measure the emitter of TR41 (right hand leg if looking at the front of the transistor) in SSB mode. you should read the same DC voltage here that you do on the power input to the radio. do you?
3. put the radio in AM mode and do the same measurement (emitter of TR41).
what DC voltage do you measure now? move the probe over to the positive side of C191. do you measure the same DC voltage there?
leave the probe there, and turn VR10 back and forth. does it vary the DC voltage at this point? if so,how low and how high?
the answers to these questions might just lead us in the right direction and show us what to test next.
again, i don't mean to distract from others' help.
LC
im coming back into this thread without knowing the updates, and may ask you to do something that has already been tried and eliminated from the list.
i may not have any answers, but maybe doing these tests one more time will lead somewhere anyway.
please don't assume anything because you've tested it already, and actually do the tests i list here. (if you want of course. feel free to ignore me LOL)
1. lift one end of R193 (220 ohm 1 watt) off of the board and measure it.
make sure it tests right around 220 ohms. if ok solder it back in place. if not, replace it.
2. put your meter to DC volts and put the negative probe to PC board ground.
now measure the emitter of TR41 (right hand leg if looking at the front of the transistor) in SSB mode. you should read the same DC voltage here that you do on the power input to the radio. do you?
3. put the radio in AM mode and do the same measurement (emitter of TR41).
what DC voltage do you measure now? move the probe over to the positive side of C191. do you measure the same DC voltage there?
leave the probe there, and turn VR10 back and forth. does it vary the DC voltage at this point? if so,how low and how high?
the answers to these questions might just lead us in the right direction and show us what to test next.
again, i don't mean to distract from others' help.
LC
. Never to be honest I always mis you opinión we are affected to Radio virus. Just give me some time. I get back soon.
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ok LC here we go
1 R193 reading 219.0 ohms
2 ssb read on rx 13.8 v on tx 11.7 v
3 AM read on rx 13.2 v on tx 4.75 v 2.5w.
now on + C191 is new AM rx 13.1 v tx 4.6 v. ssb rx 13.8 tx 11.5 v
NOW VR10 read on AM 2.6 to 6.6 v on tx. on SSB ON rx 13.1 v on tx 11.5 v
1 R193 reading 219.0 ohms
2 ssb read on rx 13.8 v on tx 11.7 v
3 AM read on rx 13.2 v on tx 4.75 v 2.5w.
now on + C191 is new AM rx 13.1 v tx 4.6 v. ssb rx 13.8 tx 11.5 v
NOW VR10 read on AM 2.6 to 6.6 v on tx. on SSB ON rx 13.1 v on tx 11.5 v
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ok so today i have removed tr 21 and I do not have carrier on ssb sound ok on AM no carrier bad audio. wait with tr 21 out i do have carrier only on usb lsb sound really good with out carrier.
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wow i really threw you for a needless loop there because i started reading the older posts and didn't see your first post.
sorry about that.
robb and nomad are already pointing you toward the same place i would. the balanced modulator.
do the checks using the frequency counter that nomad posted.
you saying that you have 5 volts on the external speaker jack has me thinking you have something miswired in the PA/CB switch.
there should be no DC voltage on that line.
if the 5 volts switches to the PA jack when you switch into PA mode, that would point right at the switch wiring.
has there been work done on the CB/PA switch?
LC
sorry about that.
robb and nomad are already pointing you toward the same place i would. the balanced modulator.
do the checks using the frequency counter that nomad posted.
you saying that you have 5 volts on the external speaker jack has me thinking you have something miswired in the PA/CB switch.
there should be no DC voltage on that line.
if the 5 volts switches to the PA jack when you switch into PA mode, that would point right at the switch wiring.
has there been work done on the CB/PA switch?
LC
the problem was at L31 with d41 on short. it was cover with the old glue. thank you for the help guys.yes IC 3 pin 3 douw to tr 32 to L31 73's
