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TOPIC: 70 MHz band

70 MHz band 26 Sep 2015 00:46 #1

In the UK we have a frequency allocation from 70.0 to 70.5 MHz. This band (or parts of it) is increasingly being allocated in europe and africa. CEPT now a footnote:"EU9: CEPT administrations may authorise all or parts of the band 69.9-70.5 MHz to the amateur service on a secondary basis."

Is it possible for the SunSDR2 Pro to transmit in this band, even with reduced performance?

Steve, G4AUC
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70 MHz band 29 Sep 2015 11:34 #2

  • VassiL
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Venturer wrote:
.....
Is it possible for the SunSDR2 Pro to transmit in this band, even with reduced performance?
Steve, G4AUC
Yes, it is possible to use SunSDR2 Pro in 70 MHz band, but Power Amplifier not working on this band. User can use low power DAC output(10 mW) and direct input RX IN. Must be used external own PA in TX mode and BPF filter in TX mode.
We will add 4M button to new version of the software.
Василий, Vasily,
Expert Electronics
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70 MHz band 03 Dec 2017 13:27 #3

  • Charly
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Hi, this is an old thread, but I guess still many reader.

I have done some rx test on 4m (SUNSDR2 Pro, indication general band) using the same setup as with my 7300 (5 El Yagi, 15dB LNA with 1 MHz wide band filter , 3dB Splitter).
Reception of usual (P14) 4m beacons is slightly better over 6hrs monitoring. I used the normal HF antenna input on SUN2PRO.
:
I my location SunSDR produces less subsampling qrm than my IC7300 - apparently a far superior lowpass filter in Sun2Pro.

How to activate TX mode - PTT (DAC Out: 10mW).
I use ESDR2, ver 1.1.3, so not sure if PTT is already implemented in new beta software.

With the high stability and excellent frequency resolution (1Hz or less) of the SunSDR , it certainly would be interesting to unlock the DAC over its full range.

73 Charly, DF5VAE
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70 MHz band 18 Mar 2018 14:34 #4

When I select 70MHz the MOX and Tune buttons are greyed out inhibiting selecting output from DAC port.
Am I missing something in setup?
Have SAWTEK 854666 filters to try in ADC/DAC PORTS, On ADC works real well kills very local VHF FM station.
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70 MHz band 09 Apr 2018 13:04 #5

Yes, it is possible to use SunSDR2 Pro in 70 MHz band, but Power Amplifier not working on this band. User can use low power DAC output(10 mW) and direct input RX IN. Must be used external own PA in TX mode and BPF filter in TX mode.
We will add 4M button to new version of the software. ....

Hello any news for ....... 4 METERS BUTTON ... is very nice to work with sunsdr the 4 meter band thanks
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70 MHz band 16 Apr 2018 11:21 #6

  • Charly
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Hello Vassil,
very good job -

But why do you (or EE) suggest to use ADC in for 70MHz reception -
I can speak only for my SUN SDR 2 - In this unit the 80 MHz low pass does not attenuate the 69-71 MHZ frequency band that I could notice a loss of sensitivity - so 4m reception is straight forward.

For Tx application the use of DAC output is mandatory - I have not seen any (Ham) wirdeband power amplifier covering 160m to 70MHz . so there is no other option.
PLEASE do not restrict with next software update the 4m RX to ADC in only -
Thanks,
Charly, DF5VAE
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Sun Pro & 70 MHz band 30 Apr 2018 08:23 #7

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As there are many (g)estimates about RX performance of the SUN SDR pro on 70MHZ just a screenshot I took this morning on 70.280.

My Sun SDR shows no degradation of sensitivity on 70 MHz - due to proximity of 80 MHz Rx lowpass.

The clean bandscope is due to supplementary bandpass filtering removing all possible under- and oversampling products from nearby high power broadcast transmitter.
The remaining peaks are timebase related and cannot be removed by external filters.

I hope direct RX to antenna connection will be kept with future updates, only 70MHz TX needs to be routed to DAC out.

Hope to see you in a few days on 70MHz

Charly, DF5VAE
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