Re: [drakelist] That old TR-3 from ebay, part two
George KB2Z [EMAIL PROTECTED] made an utterance to the drakelist gang -- If the rig was converted to 12JB6 tubes from 6JB6 there might be a problem on the filaments. I had a T4X that was converted with a simple series to parallel wire change. I have read that its a bit more detailed on a 3 tube rig. Only a thought. Good luck, George KB2Z Garey Barrell wrote: Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Mike Bryce wrote: but the tx is not running at nearly close to full power here's what I know 1. the three 12jb6 draw 250-300ma and produce about 25-40 watts, on most bands, 80 meters is much lower. Not typical behavior. Should produce most output on 80 and 40M with a little less on 20 and 15 and less on 10M. Should be at least 50 - 55% efficiency. 2. replaced most tubes with nos, but not the finals 3. did a quick peak and tweak and all stages seem to peak correctly 4. while drawing current,(250ma) the 12jb6's plates turn red, especially the one in the center. Also not typical. Running at full power, you should see no color, perhaps slight color with poor output match. One being redder than the others indicates that one or more may not be carrying their share of the load. One reason for matched trio tubes, although the primary reason is to reduce distortion products. 12GJ5's should work, and are _much_ less expensive. 5. The load control must be fully UNmessed to get power into a 50 ohmload This is also a problem. 80M it should be near fully meshed for a 50 ohm load. Typically between 4 - 4.5 on most bands into 50 ohms. 6. when the audio drive/tx drive control is fully clockwise, there is a squeal in the receive audio Check _IF_ neutralization. Most likely audio feedback through one or more stages, possible high esr in an electrolytic. Also possible lead dress has been disturbed. There is a LOT of gain running around in there. now before I drop for a trio of final tubes, is there any place I should be looking?? First thing to do is to check the value and condition of R45, the meter shunt resistor. These tend to go up in value, causing inflated plate current readings. Verify plate current meter is reading accurately. and... I have way too much s-meter. THe receiver receives just fine, I can easily hear 1uV signal, but a 50 uV signal is pegged What does the S-Meter read when the RF Gain is turned maximum CCW? Should read near full scale, but not pegged. looking for a good tube tester... what should I be looking for?? A tube tester isn't a particularly good investment unless you have a LOT of tubes to check for Good/Bad condition. Most information obtained from a tube tester can be derived from voltage measurements in-circuit along with some Ohm's law. At least one good spare for each TYPE of tube is a much better investment. If you are going to get a tube tester, get one that is a mutual conductance type that actually measures tube gain and function with dynamic signals. The military TV-7 D/U is a very good one, and most any of the Hickok brand are very good. Don't waste money on an Emission type of tester. It won't tell you anything you can't determine with an ohmmeter and a tube manual. Keep us posted! 73, Garey - K4OAH Atlanta Drake B C-Line Service CDs http://www.k4oah.com -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net -- -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
Re: [drakelist] That old TR-3 from ebay, part two
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- George - The TR-3 was originally designed for 12JB6 tubes. It was designed for mobile use, and a 12V filament supply. The TR-4 used a complex series-parallel filament string to accommodate the 6JB6 finals. The finals in the T-4X transmitters were always run with the TWO 6JB6 final filaments in series across the still standard 12V filament supply. Don't know why anyone would want to convert them to parallel, unless it was to use a non-standard supply. 73, Garey - K4OAH Atlanta Drake B C-Line Service CDs http://www.k4oah.com George KB2Z wrote: If the rig was converted to 12JB6 tubes from 6JB6 there might be a problem on the filaments. I had a T4X that was converted with a simple series to parallel wire change. I have read that its a bit more detailed on a 3 tube rig. Only a thought. Good luck, George KB2Z -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
[drakelist] That old TR-3 from ebay, part two
Guys..got the tx running, somewhat, $90 worth of new tubes and I have made a couple of contacts with this old radiobut the tx is not running at nearly close to full powerhere's what I know1. the three 12jb6 draw 250-300ma and produce about 25-40 watts, on most bands, 80 meters is much lower2. replaced most tubes with nos, but not the finals3. did a quick peak and tweak and all stages seem to peak correctly4. while drawing current,(250ma) the 12jb6's plates turn red, especially the one in the center.5. The load control must be fully UNmessed to get power into a 50 ohmload6. when the audio drive/tx drive control is fully clockwise, there is a squeal in the receive audionow before I drop for a trio of final tubes, is there any place I should be looking??and... I have way too much s-meter. THe receiver receives just fine, I can easily hear 1uV signal, but a 50 uV signal is peggedanyway... any thoughts??looking for a good tube tester... what should I be looking for??mike Mike, WB8VGE SunLight Energy Systems The Heathkit Shop http://www.theheathkitshop.com/ J e e p o|||o
Re: [drakelist] That old TR-3 from ebay, part two
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Mike Bryce wrote: but the tx is not running at nearly close to full power here's what I know 1. the three 12jb6 draw 250-300ma and produce about 25-40 watts, on most bands, 80 meters is much lower. Not typical behavior. Should produce most output on 80 and 40M with a little less on 20 and 15 and less on 10M. Should be at least 50 - 55% efficiency. 2. replaced most tubes with nos, but not the finals 3. did a quick peak and tweak and all stages seem to peak correctly 4. while drawing current,(250ma) the 12jb6's plates turn red, especially the one in the center. Also not typical. Running at full power, you should see no color, perhaps slight color with poor output match. One being redder than the others indicates that one or more may not be carrying their share of the load. One reason for matched trio tubes, although the primary reason is to reduce distortion products. 12GJ5's should work, and are _much_ less expensive. 5. The load control must be fully UNmessed to get power into a 50 ohmload This is also a problem. 80M it should be near fully meshed for a 50 ohm load. Typically between 4 - 4.5 on most bands into 50 ohms. 6. when the audio drive/tx drive control is fully clockwise, there is a squeal in the receive audio Check _IF_ neutralization. Most likely audio feedback through one or more stages, possible high esr in an electrolytic. Also possible lead dress has been disturbed. There is a LOT of gain running around in there. now before I drop for a trio of final tubes, is there any place I should be looking?? First thing to do is to check the value and condition of R45, the meter shunt resistor. These tend to go up in value, causing inflated plate current readings. Verify plate current meter is reading accurately. and... I have way too much s-meter. THe receiver receives just fine, I can easily hear 1uV signal, but a 50 uV signal is pegged What does the S-Meter read when the RF Gain is turned maximum CCW? Should read near full scale, but not pegged. looking for a good tube tester... what should I be looking for?? A tube tester isn't a particularly good investment unless you have a LOT of tubes to check for Good/Bad condition. Most information obtained from a tube tester can be derived from voltage measurements in-circuit along with some Ohm's law. At least one good spare for each TYPE of tube is a much better investment. If you are going to get a tube tester, get one that is a mutual conductance type that actually measures tube gain and function with dynamic signals. The military TV-7 D/U is a very good one, and most any of the Hickok brand are very good. Don't waste money on an Emission type of tester. It won't tell you anything you can't determine with an ohmmeter and a tube manual. Keep us posted! 73, Garey - K4OAH Atlanta Drake B C-Line Service CDs http://www.k4oah.com -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
