Date   

Re: VLF/LF/HF Active Vertical !

WQ2H <wq2h@...>
 

Just another update on the 630m side (from FN32vx).

Last night was the first night I monitored WSPR2 and JT9-1 with the CCW on 630. Extraordinary activity here on JT9-1 and -2, with several stations coming in at -10 dB from well over 1000 km away. Puzzling because we did have heavy rain and thunderstorms around us last night. For a while there I thought I was watching FT8 on 20m !

In the next few weeks I should have my 630 Tx capabilities up and on the air (thanks in part to K5DNL). I will advise of any QSO's I can muster.

Chris - great WSPR2 spots on 137, I see you have several at over 1000 km. I know it's a stretch - but I will advise once the 137 beacon is back on the air.

73
Jim, WQ2H / WK2XAH


Re: Radio

Jon Wornham
 

Hi Chris

Afraid I went for the SDRplay Duo as my main interest was airband VHF/UHF.   It works very well but it's a wee bit complicated for my poor brain :-)

Cheers
Jon

On 04/07/2019 19:10, Chris Moulding wrote:
In theory it's possible to receive on the third harmonic of the mixer injection frequency with a suitable bandpass filter to reject the fundamental response.

I recall doing this with the original Sentinel SDR receiver to reduce the spurious responses from the DDS synthesiser used in that receiver.

So applying the idea to the Sentinel 4 receiver design which covers up to 64 MHz it would be possible to extend the frequency coverage up to 192 MHz with extra relays and filters. This would cover the VHF air and marine bands.

It would need a completely new PCB design but it is technically possible.

Whether it's commercially viable is a different matter as most SDR receiver users today appear happy to use RTL-SDR or SDRPlay receivers with 8 or 12 bit receivers giving limited dynamic range compared to the 16 bit codec used in our receivers. In practice the receiver front end is suitable for use with 24 bit 192 kHz sound cards using the IQ output so wideband VHF FM reception is certainly possible.

The RF filtering on some of the SDR receivers barely meets the requirements to be called a filter.

If I was going to design a completely new SDR receiver I would go all out for a good RF design with excellent RF filtering and similar levels of isolation to the existing CCW receivers to give 24/7 all weather performance. However it wouldn't be cheap!

I expect that it would meet the needs of commercial and military customers but are enthusiasts looking for something like this?

I would be interested to hear opinions from everyone on this. Is it worth doing or are you all buying SDRPlay receivers?

Regards,

Chris



Re: Radio

Chris Moulding
 

In theory it's possible to receive on the third harmonic of the mixer injection frequency with a suitable bandpass filter to reject the fundamental response.

I recall doing this with the original Sentinel SDR receiver to reduce the spurious responses from the DDS synthesiser used in that receiver.

So applying the idea to the Sentinel 4 receiver design which covers up to 64 MHz it would be possible to extend the frequency coverage up to 192 MHz with extra relays and filters. This would cover the VHF air and marine bands.

It would need a completely new PCB design but it is technically possible.

Whether it's commercially viable is a different matter as most SDR receiver users today appear happy to use RTL-SDR or SDRPlay receivers with 8 or 12 bit receivers giving limited dynamic range compared to the 16 bit codec used in our receivers. In practice the receiver front end is suitable for use with 24 bit 192 kHz sound cards using the IQ output so wideband VHF FM reception is certainly possible.

The RF filtering on some of the SDR receivers barely meets the requirements to be called a filter.

If I was going to design a completely new SDR receiver I would go all out for a good RF design with excellent RF filtering and similar levels of isolation to the existing CCW receivers to give 24/7 all weather performance. However it wouldn't be cheap!

I expect that it would meet the needs of commercial and military customers but are enthusiasts looking for something like this?

I would be interested to hear opinions from everyone on this. Is it worth doing or are you all buying SDRPlay receivers?

Regards,

Chris


Re: VLF/LF/HF Active Vertical !

WQ2H <wq2h@...>
 

Chris, from my understanding, 1W EIRP on 137 is gargantuan.

Using the VK1SV calculator - the Hafler P3000 at 400W TOP is <500mW EIRP after going through the variometer. That places the voltage ~17kV.

Nice thing about that is that the corona arcs self-prune the adjacent foliage. LOL!

Antenna work here is ongoing - but as you would expect, the increments of progress are small. I'll be back on Tx in a few weeks.

73
Jim, WQ2H / WK2XAH


Re: Radio

Bob G3REP
 
Edited

On Mon, Jul 1, 2019 at 10:03 AM, Chris Moulding wrote:
The maximum frequency of the SDR-4+ receiver is 70.5 MHz so it will not cover
the 118-136 MHz air band.
Except with a wideband converter, plus a BPF ;-)
Next Project ?

Bob
G3REP


Re: VLF/LF/HF Active Vertical !

Chris Moulding
 

Thanks for the report on what you are hearing.

I've set up one of the VLF/LF/HF Active antennas at the workshop feeding one of the prototype Sentinel 4 receivers through a 150 kHz low pass filter to remove the LW and MW broadcast stations.

Best so far was hearing WSPR transmissions on 137.5 kHz from stations in Germany and Spain. The only problem was that the 4G modem we use in the workshop for internet access fell over that night so the spots from G4HYG/RX2 didn't get to the WSPRnet database.

I'm rather surprised how far 1W effective radiated power at 137.5 kHz can get.

Regards,

Chris


Re: VLF/LF/HF Active Vertical !

WQ2H <wq2h@...>
 

Just an update:

Using this CCW antenna I (as WK2XAH) snagged a personal best of 3594 km 4-FSK (WSPR2) Rx from WH2XND on 137.5 kHz. Plenty of good activity on 474 also (up to about 800 km), but this was a real surprise. Also spent a few hours on a Sunday morning on NDBs - picked up about 30 new ones mostly from the Canadian Maritimes and northern Quebec. Good stuff !

73
Jim, WQ2H / WK2XAH







Re: Radio

David Dudley
 

Thanks Chris


Re: Radio

Chris Moulding
 

Hi David,

The maximum frequency of the SDR-4+ receiver is 70.5 MHz so it will not cover the 118-136 MHz air band.

Regards,

Chris


Radio

David Dudley
 

Hi Chris how do I sdr -4+special on Hdsdr VHf air band thanks for reply Chris


Re: VLF/LF/HF Active Vertical !

Chris Moulding
 

Hi Jim,

Thanks for the feedback and the photo, good to hear that it's working well for you.

I'll be interested to hear a report on how it works with 2200m (136 kHz) reception.

Regards,

Chris, G4HYG


VLF/LF/HF Active Vertical !

WQ2H <wq2h@...>
 

23 Jun 2019 - 1802z - Greetings from the Granite State (New Hampshire) !

Installed the active vertical just in time to Rx the ARRL Field Day message from K6KPH in California (~4268 km) on 20m. Photo below. It's about 45' up now, and I have plenty of capacity to put a non-conductive mounting-piece in line if necessary. Installation was a snap - and noise levels appear much lower than my top-hat vertical for 2200m. (I call that the "noise magnet") Looking forward to listening for a few weeks on the low bands to see what comes along. I will share results if there is interest.

Thanks to Chris and everyone at CCW for their help on this.

73
Jim, WQ2H / WK2XAH



QRM Eliminator

g13flat@gmail.com
 

Hi Chris
Sorry to disturb you, I know you will be busy but I was wondering if you had any update on the QRM Eliminator as to its performance on your antenna at home on HF. Also what price do you think you will be selling it at if the project has commercial viability?
Thaks for your time.
KR
David


Re: The Sentinel 4 VLF/LF/HF general coverage SDR receiver covering from 5 kHz to 55 MHz.

Nick G4IRX
 

Hi Chris,

Please could you update us on the Sentinel 4 production and expected dispatch? Have sent you a direct email concerning my order placed on 10th May but cannot trace a reply.

Many thanks,
Nick G4IRX


Re: Antenna splitter on VLF to HF vertical antenna, to feed two receivers?

Tor Henneberg
 

Hi Chris,

Thank you so much for your instant reply, outstanding customer service!

I'm a bit of a dud on techie things like this, so glad I didn't ask an embarrassing  question.

Thank you for sending the right unit, much appreciated.

Regards,

Tor


On 14 Jun 2019, at 20.17, Chris Moulding <chrism@...> wrote:

Hi Tor,

It looks like I've included the wrong base unit with your antenna.

The VLF/LF/HF Vertical antenna should have two BNC outputs. It looks like I've sent you the one for the HF Active Vee antenna which has a single output.

I'll ship a replacement base unit out to you on Monday.

Regards,

Chris


Re: Antenna splitter on VLF to HF vertical antenna, to feed two receivers?

Chris Moulding
 

Hi Tor,

It looks like I've included the wrong base unit with your antenna.

The VLF/LF/HF Vertical antenna should have two BNC outputs. It looks like I've sent you the one for the HF Active Vee antenna which has a single output.

I'll ship a replacement base unit out to you on Monday.

Regards,

Chris


Antenna splitter on VLF to HF vertical antenna, to feed two receivers?

tor schofield <torschofield@...>
 

I am just putting the above antenna together. Does anyone know how the above works from one BNC output socket?


Re: Sdr-4 special

Chris Moulding
 

Although I've checked the operation of v3 of SDR Console with the SDR-4 and the Sentinel 4 receivers I never used it long enough to get around to setting the calibration settings. Versions 2 and 3 have automatic IQ balancing and would only need the gain in SDR Console adjusting to calibrate the signal level.

In the early days I used to include the IQ calibration settings for SDR Console v1.5 but stopped when the later versions came out.

For most monitoring purposes HDSDR is a lot easier to use than SDR Console unless you have a specific requirement or use the professional version of SDR Console.

Regards,

Chris


Sdr-4 special

David Dudley
 

How do I celebration settings in to sdr  console v3


Preamp

David Dudley
 

Thanks Chris

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