08 October 2014

Noble NR4SC - monoband QRP TRX for 70MHz band

Noble NR4SC is a new transceiver for the 70MHz ham-radio band, supporting SSB and CW and offering an output of 10W. It's a simple design with good usability, easy to learn and to use.

The receive section is based around a single-IF (10.7MHz) topology with diode ring mixers (RFMX-1 ? can't find any info on them), 8-pole crystal filters (3Khz SSB, 500Hz CW) and AGC in the IF section, with a DDS for a VFO. This recipe is pretty basic as far as design goes, but it can provide decent performance if executed properly - the key points being a low DDS spur and phase jitter level and a high mixer drive level. Can't comment more on this until I see schematics, but for now these aren't released.

Edit: Rob PE9PE from Noble Radio was kind enough to clear things up for me, the VFO uses a Minicircuits JTOS-100 VCO controlled by an Analog Devices AD4001 PLL, wich has an AD9850 DDS for a reference. Nice low-jitter solution ! BFO is another AD9850, good enough for that job.

Here are the released specs though:

2) 10 Watt output power
3) Built in Iambic keyer
4) Analog S-meter, not a bargraph.
5) RIT
7) Variable Speed Tuning VST
8) Wide and Narrow filter
9) Fast and Slow selectable AGC
10) Output to key an external Amplifier
11) Can be switched for QSK and Non QSK compatible Amps
12) Simultaneous display of RX and TX frequencies
13) 13.8VDC at 4 Amps TX current
14) 650 mA RX current
15) Built in loudspeaker
16) Audio output .6 Watt
17) 10.7 MHz IF output
18) RX Sensitivity -130dbm MDS
19) IF rejection greater than 100db
20) Blocking dynamic range 107db
21) Third Order Dynamic Range = 96db (IP3 = +14dBm)
22) 2nd Order Dynamic Range 87db (IP2 = +44dBm)
23) TX spurious is better than - 55dBc which meets CE ETSI EN301 783-1 standards

The claimed figures for dynamic range and sensitivity look very good for this design so they probably have nailed it properly.

This is the first SSB/CW equipment dedicated to the 70MHz (4 meters) band, until now the only options one had to cover this band was to either buy a (new and expensive) Icom IC-7100, modify an older Yaesu FT-847 or simply use a transverter paired with about any HF radio. This almost makes the 499,00 EUR pricetag seem not-so-expensive, especially if you look away from the fact that for less that 100 EUR more you can get multiband transceivers with 100W output (that don't cover 70MHz though).

All-in-all, it's a step forward for ham radio and especially for the 4m band community. For more info, you can visit the Noble Radio website; they also have a 6m version, called the Noble NR6SC.

Somebody even got the chance to play around a bit and review this radio, so if you want more first-hand info just visit Tim G4VXE's blog:


1 comment:

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