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Description
Contemporary Research QDA4-45 RF Distribution Amplifier & CombinerThe Contemporary Research QDA4 45 is an amplified RF combiner that can switch between one or four inputs, with adjustable amplification up to 50 dBmV. You can add up to 32 dBmV gain for one input, and 25 dB for four inputs. Designed for QMOD HDTV applications, the unit can receive an RF feed from QMOD modulators or QCA9 33 active combiners. Inputs can be switched between one or four inputs, with selectable gain. This compact unit mounts two across in
The Contemporary Research QDA4-45 is an amplified RF combiner that can switch between one or four inputs, with adjustable amplification up to 50 dBmV. You can add up to 32 dBmV gain for one input, and 25 dB for four inputs. Designed for QMOD HDTV applications, the unit can receive an RF feed from QMOD modulators or QCA9-33 active combiners. Inputs can be switched between one or four inputs, with selectable gain. This compact unit mounts two-across in a single rack space using CR RK1 and RK-2 rack kits (available separately), and can be mixed with QMOD HDTV modulators using the same rack kits.
Compatibility
-
- QMOD HDTV modulators
- QCA9-33 active combiner
Product Highlights
-
- Switches between one input or four input combiner
- Adds up to 32 dBmV gain for one input, 25 dB for four inputs
- Adjusts RF gain from front-panel controls and LCD display
- Provides a maximum output level of up to 50 dBmV
- Wideband, low-noise amplifier
- Low power, draws less than 8.5W
- Compact metal enclosure, mounts 2 across in 1 RU using RK1 and RK2 rack kits (available separately)
- Made in USA
Applications
-
- Use the QDA4-45 as a 4-channel, 45 dB amplifier for larger RF applications
- Combine up to four QMOD modulators
- Combine four QCA9-33 active combiners for 36 channels
- Use as launch amplifier for the RF system
- Use as booster amplifier to merge QMOD channels with existing 50 dB analog modulator systems
| Front Panel | Input Selection: 1 or 4 inputs (green LED indicators) RF Gain Selection with LED Display: 0 to 25 dB for four inputs, 0 to 32 dB for one input |
| Back Panel | 4 x Input F connector 1 x Amp out F connector 1 x DC power input (2.1 mm coaxial jack, inside center conductor positive) |
| Maximum Input | 40 dBmV |
| Isolation | 38 dB typical, 30 dB minimum, 54 to 860 MHz |
| Return Loss | Input: 30 dB typical, 13 dB in single input mode Output: 17 dB typical |
| Output | Input 1: 0 to 32 dBmV gain, low noise, linear performance through 860 MHz All Inputs: 0 to 25 gain (7 dBmV loss from combiner) |
| Maximum Output Level | +50 dBmV |
| Composite Triple Beat | -60 dB, 134 channels at +44 dBmV per channel |
| Noise Figure | 4.5 typical |
| LED Indicators | 1 x Power LED 2 x Green LEDs for input selection |
| Power Requirements | 11.5 to 13 VDC, 12 VDC typical 700 mA maximum |
| Enclosure | Durable metal enclosure, rack mountable |
| Dimensions (W x H x D) | 8.5 x 1.75 x 6.0" (216 x 44 x 153 mm) |
| Weight | 1.1 lb (500 g) |
| Packaging Info | |
|---|---|
| Package Weight | 1.9 lb |
| Box Dimensions (LxWxH) | 13.1 x 9.5 x 3.3" |
In the Box
Contemporary Research QDA4-45 RF Distribution Amplifier & Combiner
- PS12-1 1A 12 VDC Power Supply
- Limited 2-Year Warranty
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.5 ★★★★★
Based on 28 reviews
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Product Reviews
★★★★★ 3
Inconsistent
Color: Cooling Blue Cover, Size: Queen (Pack of 2)
Ive ordered two different batches of these pillows, the first was a 2 pack, the second batch was a 4 pack. The pillows that came in the 2 pack have a different quality to them. The memory foam feels thicker, takes long to depress and to spring back to form. It offers more resistance, a heavier odor (at the start), and was the pillow that I fell in love with. Things changed when I ordered the 4 pack a couple months later. There was an inconsistency between the foam in these two different batches. both sets of pillows are comfortable. The first batch being firmer means I had to remove more foam before it became comfortable but the 2nd batch being more springy, I was able to keep all the foam inside. I docked a couple stars because I’m not able to provide a consistent experience with these pillows across all three beds in my home.
If you need a pillow, order a set and be happy. If you want a bunch of memory foam pillows throughout your house, maybe look elsewhere as these may not all be identical.
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Reviewed in the United States on January 17, 2026
★★★★★ 5
Very cool and comfortable pillows. Great value.
Color: Cooling Blue Cover, Size: Queen (Pack of 2)
These pillows are everything described on the site. They do retain shape and don’t flatten out after sleeping all night. They are nice and clean looking and comfortable. The fit on my king size bed is perfect cause I prefer the size to king size. Haven’t had to wash them yet but I have had other pillows with the same material inside and the wash ability is great.
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Reviewed in the United States on May 17, 2026
★★★★★ 5
Great pillow
Color: Cooling Blue Cover, Size: Queen (Pack of 2)
The pillows feel great. Being able to remove portions of the interior allowed me and my wife to have a perfect fit. They do stay cool which seems to have helped with my restlessness.
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Reviewed in the United States on May 12, 2026
★★★★★ 5
Very comfortable and stays cool on the blue side.
Size: Upgrade Queen (2 Pack)
Awesome pillow. So comfortable and soft. Stays cool all night long on the cool side.
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Reviewed in the United States on April 14, 2026
★★★★★ 5
Better then the fake down style pillows
These shredded memory foam pillows are really comfortable. They’re soft but still supportive, and I like that you can adjust the fill to get the firmness just right. They don’t go flat easily and hold their shape well through the night. Definitely a nice upgrade if you want something more customizable than a regular pillow.
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Reviewed in the United States on April 21, 2026