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980ssb and tx star 250 hd.
- Thread starter undertaker
- Start date
Well; they way I look at it is like this: The two pills will require no more that 10w/peak to keep the amp as close to being linear as possible. So you will be feeding a class C amp(?) with a B biased radio. Not sure of the biasing of that amp; that's a guess. So a reliable watt meter and a stout dummy load may be required to set the dead key/unmodulated watts to see roughly 1/4 of the amps rated output at 13.8v. That too is a guess, but it should be fairly close.
Not familiar with that amp. Does it use 2290s or 1446s? Either pill has roughly the same input requirements IIRC.
Not familiar with that amp. Does it use 2290s or 1446s? Either pill has roughly the same input requirements IIRC.
It would work perfect on SSB. Might be a bit too much AM dead key but then it's not a very heavy swinger at all either. That radio should have an AM VR pot on the inside that's marked AM Power. Just turn the carrier down to like 2.5 watts and see how it works. 2.5 swinging 7-9 watts will work. SSB power is what 10-12 maybe?
If all you are going to use if SSB, might just want to bump the modulation up. It's set pretty low from the factory. Mine was anyways. Maybe others can verify this as well. As for the AM dead key, like 9C1Driver said, just turn the AM power down to get your dead key to about 2 watts. Any less and it messes up the internal diagnostic system. For SSB use only, I would say just leave it and add a small fan to the back or a piece of heat sink if you ate a long winded talker as they will get hot. I think they set the bias too high for the final at the factory. Or that seems like what most complain about anyways.
These are all just minor things, and not truly necessary. Maybe bumping up the modulation is, unless you plan on using a power mic. Then I would just leave it be.
Should make for a nice little setup for SSB use. Good radios to drive most any amp!! Clean and clear audio.
Enjoy the radio and be safe installing it!!
73 and God Bless.
These are all just minor things, and not truly necessary. Maybe bumping up the modulation is, unless you plan on using a power mic. Then I would just leave it be.
Should make for a nice little setup for SSB use. Good radios to drive most any amp!! Clean and clear audio.
Enjoy the radio and be safe installing it!!
73 and God Bless.
It is biased ab at idle but the bias circuit in the Tejas Star leaves a lot to be desired. The harder you drive it the closer it drifts to class C. It supplys just enough bias current to make it play nice on SSB. Most have 2290s but I have came across one that had 1446s from the factory. The 1 pill vmod they make is class C.
The 980 should be a good match on ssb. For AM I would definitely check the power out of the amp. Find a way to adjust the carrier from the radio or use the variable on the amp so the deadkey is no more than 40 to 50 watts.
Because of the way SSB works the only effect this would have is to have a potentially have a lower output power than the radio was specced as having if the mic gain was insufficient enough to reach the peak power level SSB mode was supposed to be set to. It would not make your audio any quieter. When I was doing QRP work I used to use mic-gain to lower SSB and data mode transmit peak power to milliwatts and the mic gain would often be down to single digit percentages. Never had anyone who responded say my audio was quiet.