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TOPIC: 70 MHz band

70cm transverter 19 Feb 2018 11:40 #1

Hi all,

Is it possible to connect 70cm transverter to sunsdr pro 2? If yes is the software supports as well?

Kes. :hi:
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70cm transverter 19 Feb 2018 11:52 #2

  • Rome
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Hi, Kes.
This question is answered in the FAQ, SunSDR2 PRO/ question#5 - eesdr.com/en/faq-en
ExpertSDR2 does not support the transverter mode, it will be added in the new version 1.3.
Роман, Roman
Expert Electronics
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70cm transverter 19 Feb 2018 12:00 #3

1. Is it will be same applied for 70cm transverter?
2. When is new software coming out?
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70cm transverter 19 Feb 2018 13:27 #4

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Sorry, I didn't understand your question the first time.
You can use the transverter for 70 cm right now, the ExpertSDR2 will display the actual frequency, not the resulted after transverter shift.
Роман, Roman
Expert Electronics
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70cm transverter 19 Feb 2018 13:33 #5

The FAQ #5 says about 4m/70mhz band, and I'm asking about the external transverter for 70cm or 432mhz! :hi:
This question is answered in the FAQ, SunSDR2 PRO/ question#5 - eesdr.com/en/faq-en

#5 Can the transceiver operate on the 4М (70 MHz) band and on the LW band (136 kHz)?
Answer:
You can transmit on the 4M band via low power output (DAC OUT), max 10mW. To get more power you can use an external power amplifier. To RX on this band use direct input/output of high-speed ADC/DAC. For comfortable RX operation connect a narrow pass filter to the RX IN. If necessary use an external RF amplifier.

Also, the transceiver can operate on the LW band. To receive signals above 9 kHz you can use antenna connectors А2 and А3. For TX use DAC OUT, because the internal HF power amplifier doesn't work on these frequencies.
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70cm transverter 21 Feb 2018 15:54 #6

So I presume now if you connecting transverter to one of the ant inputs it will works just will show 28mhz...if 28 if to 432mhz.
Is any plans implement transverter support in software so it's shows correct frequency (in this case 432mhz band) or it's hardware not supports this?

Regards, Kes. :hi:
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70cm transverter 21 Feb 2018 23:30 #7

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m0pkz wrote:
#5 Can the transceiver operate on the 4М (70 MHz) band and on the LW band (136 kHz)?
Answer:
You can transmit on the 4M band via low power output (DAC OUT), max 10mW. To get more power you can use an external power amplifier. To RX on this band use direct input/output of high-speed ADC/DAC. For comfortable RX operation connect a narrow pass filter to the RX IN. If necessary use an external RF amplifier.

how does one actually ptt when at 70.100MHz for example? Even with DAC selected still cant key up all greyed out.
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70cm transverter 22 Feb 2018 06:30 #8

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Hi, Kes.
We plan to add transverter support (it's a software feature) in ExpertSDR2 1.3, before summer.
Роман, Roman
Expert Electronics
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70cm transverter 22 Feb 2018 12:25 #9

could you dropm me p.m to : This email address is being protected from spambots. You need JavaScript enabled to view it.
Regards, Kes-m0pkz
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70cm transverter 04 Apr 2018 12:37 #10

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Hi kes-m0pkz

My Sun2 pro works fine in 4m Rx mode with either of the two the RF (shortwave) input. The internal Sun lowpassfilter does not yet attenuate 70 Mhz band so significantly that it affects the sensitivity.
As 70 Mhz is very close to the LP filter cut off (80 MHz) there may be variations between single units.

For the 4m Tx side, a fast way forward is to look for a comercial 70MHz module like the RA7H0608M or another more powerful module if required.
As we all wait (im)patiently for the ExpertSDR2 1.3 software release, there is enought time to locate a module and get a pcb done.

I HOPE (!!!) the new software would still allow top either use the normal RX or the ADC input and will only route the 4m TX output to the DAC out socket.
In my locations it was absolutely necessary to attenuate strong FM BC signals (6m-4m and in particular 2m) so I had to add a combined bandstop/ lowpassfilter in 4m/6m RX path.
Rx out and DAC input is already occupied with a 2m Highpass filter.

As I use two separate Antennae for 6m and 4m, both with a separate LNA - I had to find (or build) a low loss diplexer.
As pictured, I found a good one one and it saved me quite some time....)

To suppress the very strong FM BC signals, I had already set up a simple FM Bandstop filter (the one with three silverplated coils) followed by a 7th order low passfilter with 75 MHz (3dB) cut off . Such a filter is and was was absolutely necessary for my IC 7300 beforhand!) - it is helpful for the SUN SDR as well.

May be German hams will be allowed to use a part of the 4m band again in 2018 - then we may benefit from the performance of our new toy on 4m as well.

73, Charly, DF5VAE




6_4mRXfilter.jpg
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70cm transverter 09 Apr 2018 23:05 #11

A mixing problem created by a very local 250KW FM station made 4M reception impossible.
My fix was to make a BP filter comprising a SAWTEK 854666 70MHz filter proceed by a PGA103 LNA.
Result was complete removal of any mixing product problem and approximately 10dB gain .
The BP filter is working on the ADC input. The same BP filter build can handle 10mw and will be tried on the DAC port when it can be activated. Roll on release 1.3
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Sun SDR with extreme out-of-band signals - improvement with YU1LM filter 15 Apr 2018 19:39 #12

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SUN SDR improvements with YU1LM filter between RX-out and ADC in (for 2m only!)

Further down I post some screenshots taken with and without prototype YU1LM 2m Bandpassfilter.
The next filter build should have better insertion loss (present prototype 1,6 dB IL at 145 MHz), initial resonance after build was 6 MHz too low, so I had to tune the coils more than expected.

Pic 1 - SUN with RX set to WIDEBAND - VHF LNA OFF - You see the unfiltered wideband signal spectrum and their high levels
Pic 2- SUN with RX set to WIDEBAND - VHF LNA ON - RX completely overloaded
Pic 3- with RX set to Narrowband (SAW Filter) - VHF LNA OFF -
Pic4 - with RX set to Narrowband (SAW Filter) VHF LNA ON (this would be the "normal" 2m Ham band setup)
Pic5 - with RX set to Narrowband (SAW Filter) VHF LNA ON as before but with YU1EL Prototype filter inserted

Nearly all FM Broadcast Signals have disappeaared from Bandscope - Local Marineband TX Signals not visible in bandscope are 40dB down -
Basically no spurious except some low level 10MHz harmonic spurs (90-100-110-120-140-150and 160 MHZ)

The well visible noise hump is mainly caused by "man made"noise -digital cable TV, switched power supplies and spurs from Solar inverters. Depending on Antenna direction the hump will be higher or slightly lower.

Please keep in mind -
These screenshots show extreme conditions with very strong OOB conditions which few of us will ever suffer!

The SUN on its own behaves quite good already, with a supplementary bandfilter I got the noisefloor further down!
Now there are barely any inband spurious left. The external filter also removed all AM (shortwave) breakthrough.
The external filter is only active for 2m operation .

Hint: for 6m and 4m User:
If you are lucky you may find a second hand Diplexer (like the DIPX88/136). There are other similar surplusfilter around.
In nearly all cases, the Lowband (Low passfilter) and Highband (Highpassfilter) can handle 20W - (Insertionloss @ 0,4dB).

73 Charly, DF5VAE
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Sun SDR mit extremen Out-of-Band-Signalen - Verbesserung mit YU1LM-Filter 26 Jun 2021 19:53 #13

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Hallo, ich habe eine dual Band Transverter aus UA gekauft. Wie erfolgt der Anschluss an den Sunsdr2pro? Der Transverter verträgt maximal 10 mW. leider habe ich bisher noch nicht hier im Forum gefunden. Über eine Antwort per E-mail wäre ich dankbar This email address is being protected from spambots. You need JavaScript enabled to view it.
73 de Mario DJ8NU
RIG: SUNSDR2PRO, ICOM IC-7300, SPE Expert 1K-FA, RM ITALY LA-250, Kelemen Dipol wire 2 x 14 m long for 80/40/30m, 2 Element Ultrabeam Yagi for 20 to 6 m.
Club Station DM3G (show QRZ.com) Naval Number MF-1054 (MF-Runde) and RN 5074 (RNARS)
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