Date   

Re: SDR-4++ dual diversity SDR receiver

Chris Morrison
 

Previously I was looking at transceivers that allowed receive diversity. 

If I remember correctly the only ones that phase locked the receivers were the Elecraft K3, Flex 5000 (with 2nd RX option installed) and the Flex 6700.

The Yaesu FT1000MP (all of them), FT2000, FT DX5000 and the TenTec Orion and Orion II allowed stereo receive but their receivers weren't phase locked. I saw a mod for the TenTec Orion to phase lock the receivers but since the the 2nd receiver wasn't identical in performance to the 1st the results were not as good as it could be. Tentec released an update to the 2nd receiver so it performance matched the first but I never found any info on the web about having both modifications at the same time.

I was looking for a Flex 5000 with the 2nd RX installed, but ended up getting a Flex 6300. Receive diversity is the only feature missing that I looking for in a new transceiver. The Flex 6700 was way out my price range.    

Chris
M1PTT 



Re: SDR-4++ dual diversity SDR receiver

Chris Moulding
 

Welcome to the forum, Bob.

Yes, the SDR-4++ uses a single oscillator fed to two identical receivers.

Reading up on the Elecraft K3 diversity system ( I didn't know it existed until today) it uses a similar system where the oscillators are phase locked together. It's vital to do that or use a common oscillator with identical receivers to get the synchronisation right.

Regards,

Chris G4HYG


Re: SDR-4++ dual diversity SDR receiver

g3repcomms@...
 

This is precisely what the SDR-4++ does but i will let Chris confirm this :-)
(delivery this week and one big learning curve!)

73s
Bob
G3REP
--------------------------------------------

On Sun, 19/2/17, David Cutter <d.cutter@ntlworld.com> wrote:

Subject: Re: [CrossCountryWireless] SDR-4++ dual diversity SDR receiver
To: CrossCountryWireless@groups.io
Date: Sunday, 19 February, 2017, 16:34


I think you've just thrown a
firecracker into the sdr
world.
 
the obvious next step is for folks
with 2 identical sdrs
to get them to run from one oscillator and the appropriate
software. 

 
David
G3UNA
 

----- Original Message -----

From:
Chris
Moulding
To: CrossCountryWireless@groups.io


Sent: Sunday,
February 19, 2017 3:10
PM
Subject: Re:
[CrossCountryWireless]
SDR-4++ dual diversity SDR receiver


I hadn't realised that Elecraft had a diversity
receive system.
I've just searched via Google and listened to the
audio clips on N1EU's
Elecraft site.  These give an identical performance to
what I heard from
the new receiver.
I recall thinking while I was testing it to try and
make some recordings of
the stereo diversity audio. I just ran out of time.
It's got me thinking that adding a second receiver
in the Sentinel 5
transceiver would be very easy. Adding the extra soundcard
channel into the
SDR software wouldn't be so easy but I think it would
be worth the effort.
Regards,
Chris G4HYG


Re: SDR-4++ dual diversity SDR receiver

David Cutter
 


I think you've just thrown a firecracker into the sdr world.
 
the obvious next step is for folks with 2 identical sdrs to get them to run from one oscillator and the appropriate software. 
 
David
G3UNA
 

----- Original Message -----
Sent: Sunday, February 19, 2017 3:10 PM
Subject: Re: [CrossCountryWireless] SDR-4++ dual diversity SDR receiver

I hadn't realised that Elecraft had a diversity receive system.

I've just searched via Google and listened to the audio clips on N1EU's Elecraft site.  These give an identical performance to what I heard from the new receiver.

I recall thinking while I was testing it to try and make some recordings of the stereo diversity audio. I just ran out of time.

It's got me thinking that adding a second receiver in the Sentinel 5 transceiver would be very easy. Adding the extra soundcard channel into the SDR software wouldn't be so easy but I think it would be worth the effort.

Regards,

Chris G4HYG



Re: Sentinel sdr transceiver

Chris Moulding
 

Hi Pete,

We have a few projects to finish before we can complete the Sentinel transceiver design so it's likely to be a month or two yet.

At least the delay has given me chance to think of a few new features. We have just released a dual diversity SDR receiver and it would be relatively easy technically to include a diversity receiver in the Sentinel transceiver.

Obviously we haven't worked out a price yet but it will be sensible.

Regards,

Chris G4HYG


Re: SDR-4++ dual diversity SDR receiver

Chris Moulding
 

I hadn't realised that Elecraft had a diversity receive system.

I've just searched via Google and listened to the audio clips on N1EU's Elecraft site.  These give an identical performance to what I heard from the new receiver.

I recall thinking while I was testing it to try and make some recordings of the stereo diversity audio. I just ran out of time.

It's got me thinking that adding a second receiver in the Sentinel 5 transceiver would be very easy. Adding the extra soundcard channel into the SDR software wouldn't be so easy but I think it would be worth the effort.

Regards,

Chris G4HYG



Re: SDR-4++ dual diversity SDR receiver

Chris Moulding
 

I only had an hour to "play" with the receiver after the workshop tests before we shipped it out.

The amount of background noise affecting the AGC could be controlled on SSB by adjusting the AGC threshold in each session of HDSDR.

If the AGC threshold was low so that AGC was working on the background noise then headphone listening was dominated by the changes in noise level. It wasn't too bad if the audio was fed to a stereo amplifiers and wall mounted monitor speakers. The non-expert listeners present in the workshop were impressed with the SSB audio.

If the AGC threshold was adjusted so that the AGC knee was well above background noise then the background noise effectively fell away giving a good listening experience on headphones.

The medium and short wave AM broadcasts I listened to were well above the noise floor so the stereo image was fairly constant.

One thing that should be possible in SDR software would be to compare the FFT outputs from both receiver channels. If it's a similar level in both channels it's likely to be a wanted signal. If it's high on one receiver and not on the other it's probably noise and could be attenuated. This could make a very effective noise reducing algorithm as there is a definite way to prove what is a signal and what is random noise.

Very interesting to hear your experience of AM stereo. I remember reading about the C-QUAM system but as far as I know it wasn't trialled in the UK and I wondered what happened to it. I occasionally hear test broadcasts of the DRM system on short wave from Radio Romania International and it works very well.

Regards,

Chris G4HYG


Re: SDR-4++ dual diversity SDR receiver

David Cutter
 


Great project, Chris, this is a frontal assault on Elecraft' s diversity receive system: good luck, it's a terrific functionality.  Before Elecraft you had to have a rack full of the most expensive kit on the planet, now you have opened the gates to a moderate cost solution.  I think you will find others jumping on this bandwagon very quickly.
 
David
G3UNA

----- Original Message -----
Sent: Saturday, February 18, 2017 6:37 PM
Subject: [CrossCountryWireless] SDR-4++ dual diversity SDR receiver

Recently we have been asked to design a dual diversity SDR receiver for a radio propagation research project.

The receiver design was based on two SDR-4+ PCBs using a single oscillator so that the two SDR receivers were phase coherent.

The receiver has now been dispatched to the customer but following the workshop tests especially the on-air tests using two antennas the performance improvement was so surprising we have decided to offer it for general sale.

There is a new web page for the receiver with several screenshots of dual HDSDR sessions using a vertical and a horizontally polarised antenna. It's interesting to see how some signals and interference appear on one or the other antenna. The difference between the two antennas can be quite dramatic especially during fading where the polarisation of the signal is rapidly changing due to the ionosphere.

Listening to the combined audio output where both receivers were fed to a set of headphones was amazing. White noise appears as a wide stereo field while wanted signals appear in the centre of the stereo image. To hear 40m stations while the ionosphere changes the polarisation is fascinating, the signal level remains the same but the noise varies in each headphone as the AGC in each HDSDR session tracks the signal. You get the sense that you can feel the propagation changes rather than just hear them.

The web page is:

http://www.crosscountrywireless.net/sdr-4_plus_plus.htm

Regards,

Chris


Sentinel sdr transceiver

Pete Johnson
 

Hello Chris,

Do you have any idea when the Sentinel will be on sale and have you decided on a price yet?

73

Pete M0LRQ


Re: SDR-4++ dual diversity SDR receiver

WA8LMF
 

On 2/18/2017 1:37 PM, Chris Moulding wrote:
 

Listening to the combined audio output where both receivers were fed to a set of headphones was amazing. White noise appears as a wide stereo field while wanted signals appear in the centre of the stereo image. To hear 40m stations while the ionosphere changes the polarisation is fascinating, the signal level remains the same but the noise varies in each headphone as the AGC in each HDSDR session tracks the signal. You get the sense that you can feel the propagation changes rather than just hear them.

The web page is:

http://www.crosscountrywireless.net/sdr-4_plus_plus.htm

Regards,

Chris


How prominent is the shifting background noise?    Would it be significantly irritating while listening to shortwave broadcasts?
 


In the early 1980's, there was a push by several competing standards to be adopted as "the standard" for AM stereo broadcasting.   One of the criticisms leveled against some of the systems was that during nighttime long-range skywave reception shifting phases, multipath and selective fading across even the 10-12KHz bandpass of a single AM standard broadcast channel would make the stereo image wander drunkenly from side to side as propagation changed.  

The (US) NAB (National Association of Broadcasters) holds an annual trade show showcasing all the new radio-TV-proaudio hardware.  At one NAB show in the early '80s, one AM stereo proponent went so far as to hand out airline barf bags imprinted with a message to the effect that the rival system was going to sicken listeners with the unstable stereo image.

I once had a chance to listen to KFI AM 640KHz 50KW in Los Angeles broadcasting Motorola C-Quam AM stereo.  KFI is a monster signal routinely heard over most of the western US at night. It enjoys the rare privilege of being a "clear channel" at night; i.e. no other station on the channel in North America after sundown.   I once had the chance to listen to stereo music from KFI in San Francisco (about 400 miles/640 KM) to the north) in the early evening hours when KFI absolutely booms into northern California on a single skywave hop.    Most of the time, the stereo was very good with with an excellent image from left to right channels. But about every 5 or 10 minutes, the sound would suddenly lurch to the left or right channel only, followed by a distorted signal that sounded like SSB received on an AM receiver (i.e. when the selective fade notched out the carrier, followed by the receiver switching back to mono.  (C-QUAM mode in receivers was triggered by a continuous low-level 20 Hz pilot tone which would be lost when selective fading took out the carrier). This was followed by the return of reasonably good mono, followed by a return to full stereo.    

On the other hand, within it's stable groundwave coverage area  (about 100 miles/160KM radius day or night)  in greater Los Angeles the AM stereo performed wonderfully.  The greater Los Angeles area is very rugged terrain that is cut through with numerous mountain ranges up to 7000 feet/2100 m, riddled with hundreds of canyons. Even the City of Los Angeles is cut in half by a 1800 ft/550m mountain range.   This kind of terrain causes FM stereo to be a nightmare of multipath-induced distortion in many parts of the city, even just a few miles from transmitters located on Mt Wilson, about 5200 ft/1600m above the city.   The AM stereo signal worked perfectly anywhere in the area, even deep into canyons.     I had an AM/FM car radio at time that was equipped with one of Motorola's more advanced C-QUAM decoder chips.  This decoder could actually vary the IF bandwidth of the radio based on strength and S/N.    [NOTE: This was long before the era of DSP. This was all done with analog technology!]    On a nice strong local signal, the AM bandwidth would actually open up to 20 KHz plus, yielding almost FM-quality stereo audio on AM!

The technology worked, but it was killed by station managers obsessed with the loudness horsepower race in broadcasting.  C-QUAM couldn't tolerate asymmetrical "super"modulation that yielded positive peaks of 120-130-140% without hideous distortion.   (Stations would pay 10's of thousands of dollars to install magic mystery audio processor boxes that would produce this asymmetric audio in an effort to be louder than the next guy.)  With C-QUAM, the max modulation had to be limited to about 90-95%.  If you drove modulation % above this, the carrier power would approach zero on each negative swing, causing the receiver quadrature demodulator to loose phase lock on the carrier.  In turn this would cause a horrible "spattery" distortion that sounded similar to FM multipath.


Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

Live Off-The-Air APRS Activity Maps
   <http://wa8lmf.net/map>

Long-Range APRS on 30 Meters HF
   <http://wa8lmf.net/aprs/HF_APRS_Notes.htm>



SDR-4++ dual diversity SDR receiver

Chris Moulding
 

Recently we have been asked to design a dual diversity SDR receiver for a radio propagation research project.

The receiver design was based on two SDR-4+ PCBs using a single oscillator so that the two SDR receivers were phase coherent.

The receiver has now been dispatched to the customer but following the workshop tests especially the on-air tests using two antennas the performance improvement was so surprising we have decided to offer it for general sale.

There is a new web page for the receiver with several screenshots of dual HDSDR sessions using a vertical and a horizontally polarised antenna. It's interesting to see how some signals and interference appear on one or the other antenna. The difference between the two antennas can be quite dramatic especially during fading where the polarisation of the signal is rapidly changing due to the ionosphere.

Listening to the combined audio output where both receivers were fed to a set of headphones was amazing. White noise appears as a wide stereo field while wanted signals appear in the centre of the stereo image. To hear 40m stations while the ionosphere changes the polarisation is fascinating, the signal level remains the same but the noise varies in each headphone as the AGC in each HDSDR session tracks the signal. You get the sense that you can feel the propagation changes rather than just hear them.

The web page is:

http://www.crosscountrywireless.net/sdr-4_plus_plus.htm

Regards,

Chris


Re: need help with CCW

KP3FT <kp3ft@...>
 

Thanks for the info.

"1)   I'm not clear why you are trying to beat a round peg into a square hole by running native Windows programs in Linux.  I have no idea how these applications are going to interact in an alien OS."

Strange way to put it... the round peg/square hole is  an impossibility;  not sure how that relates to running native Windows apps in Linux using a Windows emulator which is possible and people do it all the time with no issues.  I've found native Windows programs quite often run better in Linux.  As for why I'm doing this?  I'm rather tight on money at the moment, so I can't buy Windows, plus I simply like Linux better.

73



From: WA8LMF via Groups.Io <wa8lmf@...>
To: CrossCountryWireless@groups.io
Sent: Tuesday, February 14, 2017 7:11 PM
Subject: Re: [CrossCountryWireless] need help with CCW

On 2/14/2017 8:46 PM, KP3FT via Groups.Io wrote:
Hi,
Tnx for the reply.  I've read through your website: http://wa8lmf.net/APRS_PSK63/index.htm and set up everything as best I could.  I attached a screenshot of CCW and SoundModem, and a screenshot of Xastir's interface settings (Xastir sees either CCW or SoundModem as an AGWPE interface?).  I'm receiving and gating other stations when I hear them, and Xastir maps them.  What I'm trying to find out, is why my own packets don't get gated by other stations.  I have something set wrong, but no idea what.  Tnx, 73.
_.

1)   I'm not clear why you are trying to beat a round peg into a square hole by running native Windows programs in Linux.  I have no idea how these applications are going to interact in an alien OS.

2)   If you are gating your own transmissions directly into the Internet, as well as sending them out on RF, you will NEVER see any evidence that anyone else heard and gated them also. 

This is due to the APRS-IS (APRS-Internet System) de-duplication mechanism which basically says "First man in wins."   Your own packets gated-direct-to-the-Internet will always reach the APRS-IS several hundred milliseconds before they are decoded off RF and passed to the APRS-IS by another station(s).  (When the APRS-IS servers see duplicate packet payloads within 30 seconds or so, they are "tossed on the floor" and never show up.   [Note this is the packet contents; not the header with path info, callsigns, etc.]  This is true, even if duplicate packets reach the APRS-IS via different servers -- all the servers exchange data with each other within a second or so of receipt.   

The only way to see if others are picking up your packets is to temporarily shut off your own Internet gateway.    

This has been repeated endlessly on APRS mailing lists:  Due to the dupe suppression mechanism, you CANNOT study RF propagation by monitoring the APRS-IS.  About all you can prove is that the band is open to one point SOMEWHERE, and only if you shut down your OWN igate functions.

[Note that my APRS map servers at <http://WA8LMF.net/map>  DO show the effects of propagation, since they show what I am hearing directly off RF in central Michigan; not via the Internet.   Of course they only show what propagation is like for ME in central Michigan.  Not what you are experiencing at your location, unless of course, you see yourself on my 30M map. Then you know there is an RF path between you and me.]



Re: need help with CCW

WA8LMF
 

On 2/14/2017 8:46 PM, KP3FT via Groups.Io wrote:

Hi,

Tnx for the reply.  I've read through your website: http://wa8lmf.net/APRS_PSK63/index.htm and set up everything as best I could.  I attached a screenshot of CCW and SoundModem, and a screenshot of Xastir's interface settings (Xastir sees either CCW or SoundModem as an AGWPE interface?).  I'm receiving and gating other stations when I hear them, and Xastir maps them.  What I'm trying to find out, is why my own packets don't get gated by other stations.  I have something set wrong, but no idea what.  Tnx, 73.

_.

1)   I'm not clear why you are trying to beat a round peg into a square hole by running native Windows programs in Linux.  I have no idea how these applications are going to interact in an alien OS.

2)   If you are gating your own transmissions directly into the Internet, as well as sending them out on RF, you will NEVER see any evidence that anyone else heard and gated them also. 

This is due to the APRS-IS (APRS-Internet System) de-duplication mechanism which basically says "First man in wins."   Your own packets gated-direct-to-the-Internet will always reach the APRS-IS several hundred milliseconds before they are decoded off RF and passed to the APRS-IS by another station(s).  (When the APRS-IS servers see duplicate packet payloads within 30 seconds or so, they are "tossed on the floor" and never show up.   [Note this is the packet contents; not the header with path info, callsigns, etc.]  This is true, even if duplicate packets reach the APRS-IS via different servers -- all the servers exchange data with each other within a second or so of receipt.   

The only way to see if others are picking up your packets is to temporarily shut off your own Internet gateway.    

This has been repeated endlessly on APRS mailing lists:  Due to the dupe suppression mechanism, you CANNOT study RF propagation by monitoring the APRS-IS.  About all you can prove is that the band is open to one point SOMEWHERE, and only if you shut down your OWN igate functions.

[Note that my APRS map servers at <http://WA8LMF.net/map>  DO show the effects of propagation, since they show what I am hearing directly off RF in central Michigan; not via the Internet.   Of course they only show what propagation is like for ME in central Michigan.  Not what you are experiencing at your location, unless of course, you see yourself on my 30M map. Then you know there is an RF path between you and me.]


Re: need help with CCW

KP3FT <kp3ft@...>
 

Hi,

Tnx for the reply.  I've read through your website: http://wa8lmf.net/APRS_PSK63/index.htm and set up everything as best I could.  I attached a screenshot of CCW and SoundModem, and a screenshot of Xastir's interface settings (Xastir sees either CCW or SoundModem as an AGWPE interface?).  I'm receiving and gating other stations when I hear them, and Xastir maps them.  What I'm trying to find out, is why my own packets don't get gated by other stations.  I have something set wrong, but no idea what.  Tnx, 73.


Re: need help with CCW

WA8LMF
 

On 2/14/2017 1:43 PM, KP3FT via Groups.Io wrote:

Hi all,

Are we allowed to attach screen-captures in messages here on the forum?  I ask because I'm having a problem with Igate and other stuff using Cross Country Messenger, UZ7HO's SoundModem, and running Xastir alongside them, and it would a lot easier to just show screen-caps of my settings.  Everything is set up and generally working; Xastir maps stations I hear, CCW is connected to SoundModem on port 4000 and is sending AX.25/PSK63 beacons.  But, my own station isn't getting gated by others, and I can't track down the problem.  Tnx, 73

Jeff KP3FT


There is no problem attaching (or embedding) images to emails in this group.  However:

1)    The max total attachment size should be kept below a total of 5-6MB.   [Email is incredibly inefficient transmitting images or any other non-text material, since each byte of non-text (binary) files is converted into approximately two bytes of hexadecimal text for transmission, and then converted back to the original form at the receiving end. This process is invisible to the user, but means when you attach a "1 megabyte" image, you are actually generating 1.5-2.0MB of transmitted data.  Since the maximum size for a single message in most email systems (varies between hosts) is around 10MB, you should never attach/embed more than about 5-6 "original" megabytes to be safe.]

2)    DON'T SAVE screen caps as JPG images !!!!  The JPG format is only for continuous-tone images; i.e. live photos.   It achieves it's compression by looking for gradual changes (gradients) of color and brightness between adjacent pixels.   When  you attempt to save images with abrupt transitions between a limited palette of solid colors (maps, program screens, technical diagrams, B&W text, etc) as a JPG, you get a hideous bubbly blurry mess at the transitions between solid colors. This renders small-point-size type in program config screens nearly illegible. Always save these kinds of screens as either a GIF image or as a PNG.


Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

Live Off-The-Air APRS Activity Maps
   <http://wa8lmf.net/map>

Long-Range APRS on 30 Meters HF
   <http://wa8lmf.net/aprs/HF_APRS_Notes.htm>


need help with CCW

KP3FT <kp3ft@...>
 

Hi all,

Are we allowed to attach screen-captures in messages here on the forum?  I ask because I'm having a problem with Igate and other stuff using Cross Country Messenger, UZ7HO's SoundModem, and running Xastir alongside them, and it would a lot easier to just show screen-caps of my settings.  Everything is set up and generally working; Xastir maps stations I hear, CCW is connected to SoundModem on port 4000 and is sending AX.25/PSK63 beacons.  But, my own station isn't getting gated by others, and I can't track down the problem.  Tnx, 73

Jeff KP3FT


Re: Comparing CCW receive-only antennas

David Cutter
 


Understood and an interesting exercise for narrow band listening, however, for general listening this would be a difficulty with the loop at any distance, so the loop antenna looks the one for that.
 
Thanks
 
David
G3UNA

----- Original Message -----
Sent: Monday, February 13, 2017 4:15 PM
Subject: Re: [CrossCountryWireless] Comparing CCW receive-only antennas

The amplifier in the HF Active Antenna has very high impedance inputs to match the capacitance of the whip antennas.

Running a wire loop between the two inputs wouldn't work very well due to the impedance of the wire loop being very low. However if you resonate the loop with a variable capacitor as a parallel tuned circuit it would match the amplifiers and should work very well.

I'm not in the workshop at the moment or I would try that out. Looks like the very first job I'll be doing tomorrow morning!

Regards,

Chris


Re: Comparing CCW receive-only antennas

Chris Moulding
 

The amplifier in the HF Active Antenna has very high impedance inputs to match the capacitance of the whip antennas.

Running a wire loop between the two inputs wouldn't work very well due to the impedance of the wire loop being very low. However if you resonate the loop with a variable capacitor as a parallel tuned circuit it would match the amplifiers and should work very well.

I'm not in the workshop at the moment or I would try that out. Looks like the very first job I'll be doing tomorrow morning!

Regards,

Chris


Re: Comparing CCW receive-only antennas

David Cutter
 


Thanks, Chris, that's a great summary.  Sounds like the HFALA is the best for us.  However, how would the HF active antenna work if the loop antenna from the HFALA were attached?  Come to that, any "small" loop? 
 
David
G3UNA

----- Original Message -----
Sent: Monday, February 13, 2017 1:34 PM
Subject: Re: [CrossCountryWireless] Comparing CCW receive-only antennas

I often get asked which active antenna is best and my usual answer is "It depends on what you want it to do".

Running through the antennas:

Broadband Active Antenna: This antenna was designed for airband monitors who want a single antenna to cover VHF airband, military UHF airband and ADS-B aircraft beacons. It also works on HF as an electric field antenna so that HF signals from transatlantic aircraft can be heard. If you can mount this high and in the clear away from any electrical wiring it works well over a wide range of frequencies. Don't expect wonders if it's just propped up against a wall downstairs. Coax fed with DC power fed up the coax cable.

HF Active Antenna: This antenna was designed for the RSGB noise measurement project. It's designed to minimise noise pickup from the power supply or feeder cable. Again if you can mount this high and in the clear it gives great results on HF. If used indoors it can pick up a lot of RF noise by capacitive coupling to the electrical wiring. Depending on the version it may be useful for VHF FM reception. The "New York" version has a 70 MHz low pass filter to reduce overload from megawatt EIRP FM transmitters on very high buildings. Uses ethernet cable as RF feeder and DC supply.

HF Active Vee Antenna: The same amplifier as the HF Active Antenna with double length whip elements in a vee configuration for HF use. Excellent for HF NVIS, ground wave and general HF listening. Again best mounted in the clear outdoors. Not recommended for indoor use. Uses ethernet cable as RF feeder and DC supply.

HF Active Loop Antenna: Probably our best HF antenna. Surprisingly good indoors at low level as there is no capacitive coupling to nearby electrical wiring. Excellent for all HF listening as a low noise receiving antenna. We have sold many to contest groups and professional HF listening stations as a remote antenna for use while transmitting on the same site. It was originally designed for use as a low noise HF antenna mounted above a HF transmitting antenna. If mounted high and in the clear DX performance is excellent. RF overload protection on this as well as the other antennas is excellent. Some performance on VHF up to the 2m band but the antenna pattern isn't good on VHF. Uses ethernet cable as RF feeder and DC supply.

Regards,

Chris



Re: Comparing CCW receive-only antennas

Chris Moulding
 

I often get asked which active antenna is best and my usual answer is "It depends on what you want it to do".

Running through the antennas:

Broadband Active Antenna: This antenna was designed for airband monitors who want a single antenna to cover VHF airband, military UHF airband and ADS-B aircraft beacons. It also works on HF as an electric field antenna so that HF signals from transatlantic aircraft can be heard. If you can mount this high and in the clear away from any electrical wiring it works well over a wide range of frequencies. Don't expect wonders if it's just propped up against a wall downstairs. Coax fed with DC power fed up the coax cable.

HF Active Antenna: This antenna was designed for the RSGB noise measurement project. It's designed to minimise noise pickup from the power supply or feeder cable. Again if you can mount this high and in the clear it gives great results on HF. If used indoors it can pick up a lot of RF noise by capacitive coupling to the electrical wiring. Depending on the version it may be useful for VHF FM reception. The "New York" version has a 70 MHz low pass filter to reduce overload from megawatt EIRP FM transmitters on very high buildings. Uses ethernet cable as RF feeder and DC supply.

HF Active Vee Antenna: The same amplifier as the HF Active Antenna with double length whip elements in a vee configuration for HF use. Excellent for HF NVIS, ground wave and general HF listening. Again best mounted in the clear outdoors. Not recommended for indoor use. Uses ethernet cable as RF feeder and DC supply.

HF Active Loop Antenna: Probably our best HF antenna. Surprisingly good indoors at low level as there is no capacitive coupling to nearby electrical wiring. Excellent for all HF listening as a low noise receiving antenna. We have sold many to contest groups and professional HF listening stations as a remote antenna for use while transmitting on the same site. It was originally designed for use as a low noise HF antenna mounted above a HF transmitting antenna. If mounted high and in the clear DX performance is excellent. RF overload protection on this as well as the other antennas is excellent. Some performance on VHF up to the 2m band but the antenna pattern isn't good on VHF. Uses ethernet cable as RF feeder and DC supply.

Regards,

Chris


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