2 kw / 2 - 30 MHz
SOLD ONLY with our RF-110A Amplifiers
NOTE: Sold only with our RF-110A amplifiers (above).
Scientific Radio Systems SR-204 Front Panel & Chassis Frame
Included on the front panel are the controls, switches, jacks and a lighted 0 - 1 mA meter marked in "S" units and watts. An ancillary board for setting individual transmit audio levels for each channel is mounted and includes six 10k ohm trimpots and miscellaneous parts.
The complete receive audio board that takes output from the detector and boosts it to up to 6 watts out into the 4 ohm speaker is also mounted on the front panel and is included. No more headphones only listening. Also on this board are the transmit tone oscillator for tune up of an SSB transmitter, 2 matching line inputs from 600 ohm balanced feeds, one for transmit audio, the other for receive audio and the T/R relay driver.
Also in this frame is the majority of the high power RF deck. This deck was designed to use two 6LQ6 sweep tubes (not included) driven by an MJE340. The MJE340 was driven by a 2N1613 from another board (not included) which is a general purpose 1/2 to 3 watt transitor All parts for the RF deck are included except: two 6LQ6 tubes, 4PDT, 12 vdc, T/R relay and the tank circuit (coil and variable capacitors). It also includes a calibrated RF sampler used to drive the front panel meter through existing wiring on the chassis.
The front panel channel switch extends though the RF compartment and could be used to select pre-tuned tank circuit taps and capacitors. The switch is a 7 pole, 12 position switch with 3 poles in the RF compartment and 4 in the front panel compartment. An alternative is to remove the channel switch for a single band radio and mount the frequency tuning control in its place.
In the original design, this radio included the power supply in the frame to provide all required voltages from either 115 / 230 vac or 12 vdc. If you want to use the 6LQ6 finals, buy the optional power supply of your choice below. Or, gut the RF deck and install you own solid state PA - no power supply needed. A 3-5/8" externally mounted square fan is required for high power operation. A suitable unit is listed on our MUFFIN FANS page.
A full manual for the SR-204 is included with each unit.
Select from the SR-204 which has a gray silk screened front panel with handles or the SR-204D (below) which is olive drab with no handles. Internally they are the same.
- External dimensions: 13-3/8" wide x 15" deep x 4-1/4"H
- Power Supply section: 6-1/4" x 6-1/4"
- Receiver Section: 4" x 6-1/4"
- PA Compartment: 6-1/4" x 6"
- Exciter Section: 4" x 5"
15kw @ 13.56 MHz
- Input: 208v AC, 3 ph, 50/60 Hz
- Output: 15kw @ 13.56 MHz
- Dimensions: 34" x 34" x 65.5"H
- Weight: 1,350 lbs
2 kw @ 13.56 MHm
- Input: 208v AC, 3 ph
- Output: 2 kw @ 13.56 MHm
- Dimensions: 60"H x 23"W x 26"D
13.56 MHz
Scientific Radio Systems SR-204 Front Panel & Chassis Frame
- Input: 115 / 230 vac, switch selectable
- Output: 12 vdc reg. 18 vdc, -40 -60 vdc bias, -60 vdc, +84 vdc, +157 vdc and +550 vdc
- Input: 12 vdc
- Output: 12 vdc reg. 18 vdc, -40 -60 vdc bias, -60 vdc, +84 vdc, +157 vdc and +550 vdc
RF Amplifier
On board thermal sensors on the output transistors provide input to an external bias control circuit to reduce output power due to high temp and control an external fan on the heatsink (not included).
Heatsink is 9-1/8" x 4" x 1-5/16" - PC board adds 7/8" to thickness. Manual included. Includes filter. Transistors alone are over $200.
RF Amplifier
This board also includes RF output voltage and current sensing to detect SWR variations. As the output SWR diverges from 50 ohms, it is evidenced by output voltage and / or current changes. As a result, the bias on the final transistors is adjusted to reduce power output. Similarly, the output transistor case temperature monitored on the PA board is also used to control an external cooling fan and adjust the bias as needed. Supply voltage changes are also an input to this bias control circuit to reduce power output as supply voltage drops so that the output stage remains linear.
There are also 5v and 8v regulators on this board for various uses in the original radio. Manual included. Circuit board measures 12" x 7" x 1-3/4".
Military Tank Style!!
• TUBES: (2) 3B28, (2) 811A, (2) 5763, (1) 6X4, (1) 0A3, (1) 12AT7, (1) 5814
• Frequency Meter 60 Hz Reed Type
• Oil Capacitors (2) 1500v, 4 µF
• Plate Transformer: Freed 30994, 115v, 45-60 Hz primary // 2540 vct 400 madc secondary.
Measures 6" x 7" x 7" high. Hermetically sealed.
• Filament Transformer: Freed 30993, 115v, 45-60 Hz primary // 2.5v @ 10 amps secondary. 1050v high pot. Measures 2-3/4" x 3" x 4" high. Hermetically sealed.
• Modulation Transformer: Freed 31001, 18k ohm center tapped primary // 165 ohm secondary. Drives plates of (2) 811A's. 80 watts. Hermetically sealed.
• Plate Choke: Freed 30997, 4 Hy @ 400 madc, 35 ohms DCR, 1350v high pot.
Measures 3-1/2" x 4" x 6" high. Hermetically sealed.
• Swinging Choke: Freed 30996, 6-12 Hy @ 400 - 100 ma, 40 ohms DCR, 1964v high pot.
Measures 4" x 4" x 5-1/2" high. Hermetically sealed.
• Filament Transformer: Freed 30999, 115v, 45-65 Hz primary // 6.3 vct @ 8 amps and 6v @ 1.5 amps secondaries. Measures 3" x 3-3/4" x 5-1/2" high. Hermetically sealed.
• Impedance Transformer: Freed 31002, 8 kct @ 50ma to 2500 ohm ct @ 50ma.
Measures 3" x 3-1/4" x 5" high. Hermetically sealed.
2 kw HF Amplifier Deck
1.6 to 25.1 MHz *
* 1.6-25.1 MHz in 9 bands including these frequencies:
- 1.6 - 4.5 MHz, 6 - 7 MHz, 8 - 9 MHz, 12 - 13 MHz, 16 - 17 MHz and 22 - 25.1 MHz
- 4CX1500B PA Tube included
- 4 panel meters to monitor RF amps, grid and plate RF volts and a multimeter
- 2 air variables
- 2 nice, large radio switches
- 3 nice, silver edge wound coils that are tapped
- Input tuning
1.6 - 30 MHz
Features from left
to right:
• Motorized Inductor |
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Side view of SR-110 | Front view of SR-110 | Bottom view of SR-110 |
- (1) Radio Switch 4P12T Model 88 high voltage / current band switch
- (2) Johnson 122-275 ceramic sockets
- (16) Various doorknob transmitting capacitors
- (1) Fan for tubes w/ airflow switch
- (1) B&W Model 802 Plate Choke1) Complete manual compliment for finished equipment "SR-110" in English, French or Spanish!
SR-110H
Added features: |
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• Chimneys |
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Top inside view of SR-110H | Front view of SR-110H |
1.6 / 30 MHz
• (3) 6146W's in Parallel • 12BY7A Driver • 12DZ6 Driver |
• 750 vdc @ 1/2 amp • 240 vdc @ 1/2 amp • 120 vdc @ 50ma • 12 vdc @ 1 amp • Filaments for Tubes |
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SR-200 Series - 3 Tube Deck |
- 3 - Brand New General Electric 6146W's - Valued at $180 alone!
- Great building block for QRP Linear Amplifier. Milliwatts drive to full output.
- Full manual and schematic documentation included with purchase.
Input Boards
Part Number | Mfg. P/N | Frequency | Price | |||||||||||||||||||||||||||||||||||||||||
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6 or 10 Meters?
Control panel view (back?) of amplifier. Verniers control air variable capacitors. Also shown are blower, in/out N connectors, voltage input terminal block. | ||
Inside view of 42 MHz KW |
- (1) 4PR-1000A Eimac tube, chimney
- (2) 20-110pF 4kv air variables
- (1) 500pF 13kv Draloric PD70*
- (1) 50pF 14kv Draloric PD70*1) 1200pF 13kv Draloric PD100
- (1) EBM G2E160AD01-01 High Volume Blower, 220v, 1.15 amps
Transmitter / Receiver
- Mullard JP9-2.5 Magnetron with WR-90 output.
- Six 6EW6
- 6EA8
- Four 0A2
- 115NO180 Time Delay Relay
2500v to 3000v
2500v to 3000v
- Primary: 105/115/125/210/230/250 volts
- Secondary: 2500/3000 volts
- Apparent Power: 2500 VA
Complete Amplifiers