572B (T160L)
Power Triode
Base & Bulb ( Omalley DS 2/65)
Mechanical Data
EIA Base ...................................... 3G
Electrical Data
Heater Voltage ................................ 6.3 V
Heater Current ................................ 4.0 A
Direct Interelectrode Capacitances (approx)
Triode
Input ......................................... 6.0 pf
Output ........................................ 0.8 pf
Grid to Plate ................................. 6.0 pf
Maximum Ratings (Design Center Values)
Triode Class C
Plate Voltage ................................. 2500 V
Plate Dissipation ............................. 225 W
Bulb Temperature (At Hottest Point) ........... 200 °C
Maximum Ratings (Design Center Values)
Triode Class B
Plate Voltage ................................. 2500 V
Plate Input ................................... 560 W
Plate Dissipation ............................. 225 W
Plate Current ................................. 250 mA
Grid Current .................................. 50 mA
Bulb Temperature (At Hottest Point) ........... 200 °C
Characteristics and Typical Operation
Class B Amplifier
Plate Voltage ................................. 2500 V
Grid No. 1 Voltage ............................ 0 V
Peak Grid No. 1 Voltage........................ 110 V
Grid No. 1 Current ............................ 35 mA
Amplification Factor .......................... 190
Plate Current (Zero Signal) ................... 25 mA
Plate Current (Maximum Signal) ................ 225 mA
Driving Power ................................. 4.2 W
Load Resistance ............................... 6.9K Ω
Power Output (approx) ......................... 400 W
Maximum Frequency ............................. 30 MHz
Characteristics and Typical Operation
Push-Pull Class B Amplifier
Plate Voltage ................................. 1500 V
Grid No. 1 Voltage ............................ 0 V
Peak Grid No. 1 Voltage........................ 170 V
Amplification Factor .......................... 190
Plate Current (Zero Signal) ................... 60 mA
Plate Current (Maximum Signal) ................ 350 mA
Driving Power ................................. 5.5 W
Load Resistance ............................... 12.5K Ω
Power Output (approx) ......................... 380 W
Characteristics and Typical Operation
Push-Pull Class B Amplifier
Plate Voltage ................................. 2000 V
Grid No. 1 Voltage ............................ 0 V
Peak Grid No. 1 Voltage........................ 160 V
Amplification Factor .......................... 190
Plate Current (Zero Signal) ................... 70 mA
Plate Current (Maximum Signal) ................ 360 mA
Driving Power ................................. 7.0 W
Load Resistance ............................... 16.5K Ω
Power Output (approx) ......................... 530 W
Characteristics and Typical Operation
Push-Pull Class B Amplifier
Plate Voltage ................................. 2500 V
Grid No. 1 Voltage ............................ 0 V
Peak Grid No. 1 Voltage........................ 210 V
Amplification Factor .......................... 190
Plate Current (Zero Signal) ................... 80 mA
Plate Current (Maximum Signal) ................ 400 mA
Driving Power ................................. 8.5 W
Load Resistance ............................... 15K Ω
Power Output (approx) ......................... 730 W
Characteristics and Typical Operation
Class C Amplifier/Oscillator
Plate Voltage ................................. 1250 V
Grid No. 1 Voltage ............................ -50 V
Grid No. 1 Current ............................ 45 mA
Amplification Factor .......................... 190
Plate Current (Maximum Signal) ................ 140 mA
Driving Power ................................. 5.6 W
Power Output (approx) ......................... 135 W
Maximum Frequency ............................. 30 MHz
Characteristics and Typical Operation
Class C Amplifier/Oscillator
Plate Voltage ................................. 1500 V
Grid No. 1 Voltage ............................ -70 V
Grid No. 1 Current ............................ 40 mA
Amplification Factor .......................... 190
Plate Current (Maximum Signal) ................ 173 mA
Driving Power ................................. 7.0 W
Power Output (approx) ......................... 200 W
Maximum Frequency ............................. 30 MHz
Characteristics and Typical Operation
Class C Amplifier/Oscillator
Plate Voltage ................................. 2000 V
Grid No. 1 Voltage ............................ -70 V
Grid No. 1 Current ............................ 30 mA
Amplification Factor .......................... 190
Plate Current (Maximum Signal) ................ 200 mA
Driving Power ................................. 5.5 W
Power Output (approx) ......................... 300 W
Maximum Frequency ............................. 30 MHz
Shuguang 572B's (China)
I bought a matched pair of these from Chen, ebay dealer from Hong Kong. I paid under 85 dollars for them shipped to my door from China. It took about 18 days. When I first installed the pair, I let them burn in with just an idle "no power applied" condition for 12 hours. After applying drive, a strange scary thing occured. The graphite anodes (plate) would glow BRIGHT ORANGE within a minute of sideband or half a minute of AM. The were bordering on WHITE hot. I assumed they were bad or poorly designed. I had found a spec sheet that only rating them for 1250 volts on the plate max. This was not in accordance with the original 572B specs. I figured they were made with just audio in mind and weren't really meant for RF. So I ordered a matched pair of NOS (new old stock) Svetlana 572B's from K5SVC, another ebay dealer, who assured me the Svetlana's were tested for RF application and matched in a custom modified SB-200 with two meters. After a week one of these tubes developed a problem. (See the Svetlana section below for more info) I reinstalled the Shuguang 572B's and very shortly the plates were behaving nicely and barely blushing in the middle with long "old buzzard" transmissions. Carl, KM1H, as someone very knowledgable about the 572B's (he provides a service converting SB-200's for use on 6 meters) suggested that maybe the getter in the pair were "incomplete" and the tubes needed to finish the process and this caused the initial bright orange coloring. At anyrate, the tubes are behaving and working fine business at the 572B specifications now.
Svetlana 572B's (Russia)
The pair of Svetlana 572B's came from the next state over from Frank, K5SVC. As a tube dealer, he had obtained a large supply of these tubes and modified a Heathkit SB-200 with two meters to check them out and also to create matched sets. My first pair seemed to work great, showing a bit of blushing on the plates but nothing too orange. Then after about a week something failed quick. My SB-200 would stay keyed up now when powered on and the grid voltage pegged the meter in a negative direction. Substituting another tube in revealed that one of the Svetlana's was at fault. Frank, K5SVC, backs up his product and okayed me to return the pair for another. Interelectrode capacitance may be a bit higher in the Russian tubes and Carl, KM1H, has responded about this in the following post on amfone.net.
Notes from Carl, KM1H, from amfone.net post:
Id say that half of SB-200, or SB-220 for that matter, problems are original builder induced. With well over 250 of them coming thru here for 6M conversion Ive seen more than a few strange ones.
The 572B isnt much different than the 1929 211 from which the 811 was derived. And the 572B is nothing more than an 811 with a graphite plate. On 10-15M the circuit is not fully neutralized and you can wind up with a TPTG oscillator under certain mistuning conditions.
A couple of things can help.
1. Straighten up the input section mess if component leads are excessively long, helter skelter, etc.
2. Add a .01 1KV disc cap from each grid connection to ground.
3. Lift the input RF off the socket pin used as a tie point. There is no internal tube connection but enough RF of some unknown phase is introduced through coupling to a filament pin.
4. Especially with non USA tubes a bit more operating bias works well. Start by making sure that you have a full -125VDC in standby. A leaky C-3 and C-19 can drag this down. In operating mode without RF drive the bias is around -2.5V and this is derived thru the relay coil resistance and R-18. Change the value of R-18 by replacing or paralleling another resistor so you obtain around -4 to -5V.
5. Place a 10-12 pf 1 KV silver mica or 2-5 KV doorknob directly across the 40 and 20M switch contacts. While this isnt neutralization related it will snub the high RF voltages developed during tuning due to the shorted turn effect of the switch. It will help protect switch contacts from vaporizing (and Tune cap arcing) which is not due to junk science VHF parasitics hot air as a few try to make us believe. Since that new cap raises the minimum C of the Tune cap it may be necessary to slightly stretch the 10-15M coil to compensate.
6. Make sure the parasitic suppressor resistor is within 20% of 33 Ohms.
Any particular SB-200 might need some or all of the above.
Carl
KM1H