It will have even better IP3 and even lower oscillator phase noise. The HF7070 will be a larger desktop receiver with a larger bright LCD, front keypad, final DSP IF for almost limitless filter bandwidth selection. Like the AR7030, it will be constructed in England to exacting standards. 15 m random wire SINFO 25353 Heard from 07h46 UTC (tune-in) to 08h05 UTC (end of the broadcast).The Zycomm HF7070 may be available in very late 2011. Win Radio Excalibur Pro with approx.
Up for sale is a aor receiver. This one had the bottom loose & 1 circuit board has it's screws removed. AOR SR2000a Radio Receiver/scanner. Condition.AOR SR2000a FFT Radio Receiver/scanner. These estimates are based on the following prices: Year.
These results were possible due to the outstanding quality of the 9MHz crystals supplied to him by the German firm Quarz Technik. Like the CDG2000 receiver the AR7070 is sensitive enough not to require a preamplifier before its first H mode mixer.These receivers are only as good as the linearity of their crystal roofing filters and Martein was able to build a 4 pole 2.5 KHz bandwidth roofing filter at 9MHz with 1dB insertion loss and IP3 in band of 35dBm and out of band of 56dBm. The AR7070 is an up conversion receiver that uses the techniques of the receive section of the CDG2000 transceiver that Martein improved upon to make his 'holy grail' receiver with a 9MHz IF. In my opinion it will prove to be the best up conversion HF radio of all time.The AR7070 has been designed by my friend John Thorpe the designer of the highly acclaimed AR7030 HF receiver and also the designer of the 'HF' series of receivers made in Matlock by Lowe Electronics in the late 1980s and early 1990s. A radio talk tour to offer his views on the controversy over lyric content.Martein and I have both been involved in the research that made this radio possible.
Aor 7030 Radio Full Potential Performance
However if the following circuitry after a wide roofing filter is not linear enough before the 24 Bit ADC the full potential performance of the 24 Bit DSP system will not be realised. So in an up conversion receiver you want a wide roofing filter that has good in-band linearity not a narrow one. He had shown conclusively that for a given quality of quartz in band IP3 of the filter degraded at roughly 6 dB per octave reduction in design bandwidth.
The first IF amplifier drives a 4 pole roofing filter and it is this filter that sets the in band IP3 of the radio at the antenna (20 dBm). These filters also protect the first IF amplifier from strong out of band signals. After the first H mode mixer two 2 pole filters are connected via hybrids to terminate the mixer. The in band IP3 is 26 dBm and out of band at 20 KHz tone spacing is 38 dBm. They were supplied by the British firm TFC (Total Frequency Control). In the case of Martein's down conversion receiver with a 9MHz IF the H mode mixer is the limitation in receiver IP3 performance due to the fabulous 56 dBm out of band IP3 of his crystal filter.The roofing filters in the AR7070 have a 15KHz bandwidth centred on 45 MHz.
These fabulous results are due to advanced fixed point DSP software that is not compromised by poor linearity in the analog signal path to the 24 Bit audio ADC. At 200Hz test tone spacing the radio still has an IP3 of 19dBm giving a IP3 dynamic range of 97dB in an SSB bandwidth. The circuitry after the roofing filters including the 45 KHz IF is highly linear and does not compromise the performance of the 24Bit audio ADC.
With the receiver noise figure being around 20 dB this gives a close in IP3 dynamic range of only 77dB compared to the AR7070s 19 dBm and 97 dB dynamic range in an SSB bandwidth. The test using a 15 KHz wide filter clearly showed that the IP3 within the roofing filter bandwidth was only -8.5 dBm. He did these tests with different roofing filter bandwidths. Also unlike Martein's 9 MHz CW filter the 7.5 KHz bandwidth filter had a worse out of band IP3 performance.To illustrate a particular point: The review by Peter Hart G3SJX of the Yaesu FTDX5000 in the June 2010 RadCom measured close in IP3 on the 7MHz band using the down conversion receiver. In band IP3 followed Martein's results and was 7dB worse than the 15 KHz bandwidth unit.
This is around 100dB for the AR7070. Therefore the dynamic range of the receiver in the FTDX5000 could be increased by improving the linearity of the signal path following the roofing filters.Most reviewers of amateur radio equipment do not quote IP2 linearity. The close in phase noise of the local oscillator in the FTDX5000s down conversion receiver is superior to the AR7070 which after all is an up conversion radio. However the 97dBm close in IP3 dynamic range of the AR7070 is limited by reciprocal mixing to 82 dB which is still better than the FTDX5000s down conversion receiver at 77 dB.
It also is a measurement that should be made on the latest SDRs that use direct sampling at the antenna with 100MHz 16 Bit ADCs. Obviously some sort of pre selector could improve IP2 significantly on the AR7070. The IP2 for the AR7070 is similar to that in the AR7030 receiver and it has not surfaced in practice as a big issue.
Martein also identified an AM noise issue with the latest 14 bit DAC DDS chips from Analog Devices. As things stand at the moment suppression of spurs was deemed not good enough for an up conversion radio. Although the use of a DDS chip directly as the local oscillator was considered. This is similar to that used in the AR7030 receiver but of improved performance. The AR7070 still uses a PLL/DDS solution for the frequency synthesizer using a double tank VCO.
Martein has done quite a bit with noise plateau’s in the AD9910 investigation which is covered elsewhere on this web site. The present phase detector has some useful features but uses a band gap voltage reference and these have a very characteristic noise profile with a plateau that extends outward to about 200KHz. However, being a perfectionist in my opinion it could be further improved in the transition region (1Khz to 8KHz from carrier) with a better phase detector. However they are interested in doing a 16 bit part and when this is available it may prove suitable for use in up conversion radios and give much better close in phase noise that would increase very close in receiver dynamic range for a signal path design like the AR7070.The phase noise on the local oscillator for the AR7070 is excellent for an up conversion radio and in fact is better than a state of the art commercial down conversion receiver. Their latest DDS chip will be a 12 bit DAC 4GHz clocking device.
They show why this radio has such a fabulous on air performance. However there are no plans to alter circuitry in the radio due to the already excellent overall phase noise profile of the AR7070s present local oscillator.The technical measurements presented here are first rate for an up conversion radio. An investigation of this effect is worthwhile for the knowledge gained. I have mentioned my suspicions on this to John Thorpe but the only way to be certain about this is to obtain an internal circuit of the phase detector chip so we can see how the band gap reference voltage affects the charge pump. The present phase detector uses a band gap reference un-bypassed and it looks like the limit within the PLL bandwidth is -116dBc/Hz, which is still an excellent figure at 200Hz off carrier.
Aor 7030 Radio How To Make State
All are directly linked to the performance of its frontend. When the full story behind the development of this receiver is written up for Radcom you will see that some of the important analog circuitry used in the receiver has been due to the ideas of radio amateurs on both sides of the pond.Below is presented extensive measurement data provided to me by John Thorpe regarding key aspects of the AR7070 HF receiver. The plan is to build ten production prototypes in the near future but this has been complicated by the global recession and as a result some components are on extended lead times. John must have done a good job with the DSP software because everyone has been very enthusiastic about the AR7070s on air performance.As you know Martein's web site has been dedicated to information on how to make state of the art receivers and that is why this information is presented here.
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