Re: Is this Wellbrook wide aperture loop faulty?

#15755

But do remember that active antennas are normally powered with DC down the coax too!? You only need to put substantial capacitance in the common ground to avoid issues or use an autotransformer with a C in the common.? Turns ratios of? 5:4 or 6:5 work well but 11:9 is almost perfect.

73 Alan G8LCO

Re: Good Vibrations?

#15753

开云体育

Q. Why would anyone use locking compound on plastic?

A. Because they think it will lock parts together without the risk of cracking when overtightening.?? (You advised locking compound with nylock nuts.)

People generally use too much compound, only a minute amount in the thread space is needed. If excess runs off onto plastic parts then they can disintegrate over time. There are a very wide range of plastics nearly all of which are compounds with various additives to improve moulding properties, colour, flexibility and toughness so the reaction to compound solvents is hard to predict. People may think that Plastics are solids and impermeable however that's not true for many plastics. Nylons absorb water for example as do some uncured silicone rubbers which " set" through their bulk? by exposure to water.

Thread locking compounds set to a plastic mass when squeezed between metal surfaces, the exclusion of oxygen and the presence of metal ions trigger the reaction. So the compound cannot work on plastic parts but the solvents may enter microcracks in plastics and cause extensive damage to some plastics. Obviously the product is supplied in a plastic bottle -not all plastics are at risk!

See

A safer option is to use two nuts, the second being used as a lock-nut.

73, Alan G8LCO.

Re: Good Vibrations? / locking compounds

#15752

开云体育

I have seen nail polish used before and well.

The other one is “glue”. Super glue is not so strong under shear stress as strain so things can still be undone.

Andrew VK5CV.

?

Sent from for Windows

?

Show quoted text

From: kevin asato via groups.io
Sent: Tuesday, 4 January 2022 10:34 AM
To: [email protected]
Subject: Re: [loopantennas] Good Vibrations? / locking compounds

?

I have used my daughters finger nail polish as thread locker. Yes it does contain acetone but if used sparingly and on the end of the screw and nut, should not cause a plastic meltdown event. It worked so well, I now have a nail polish collection of my own!

73,
Kevin
kc6pob

On Sunday, January 2, 2022, 10:12:29 PM PST, Fred Moore <n40cla@...> wrote:

?

Good?morning all.??

?

I have been following all the comments about vibrations on the antenna causing mounting hardware to loosen.? I have used the following type of hardware for years at commercial sites and can't remember where we have had any hardware loosen up for whatever?reasons.? The attached link below uses one nut and one split ring washer at every point where any tightening is to happen for mounting.? All the big boys, 2 way communication, cell site antennas etc use this type of hardware and once it is up it is never touched again until it has to come down or be moved.? No criticisms intended, just my opinion.

?

Fred - N4CLA

?

On Sun, Jan 2, 2022 at 7:45 PM Leigh Turner <invertech1@...> wrote:

Good fit-for-purpose cautionary advice here Alan....

Leigh
VK5LT

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Alan
Sent: Monday, 3 January 2022 10:50 AM
To: [email protected]
Subject: Re: [loopantennas] Good Vibrations?

I would NEVER USE LOCKING COMPOUND ON PLASTICS. Many locking compounds can destroy plastic parts over time, they are formulated for locking metal part not plastics.? Same goes for some greases. One former employee used locking compound on plastic nuts, cost ?35,000 to replace the parts.

One Italian manufacturer used a grease to ease driving screws into plastic pillars. After a year the pillars disintegrated and cost the manufacturer a lot of money.

73, Alan G8LCO.

?

Re: Best SDR Receivers

Andy - Arlington TX

#15751

I appreciate this SDR discussion, and the information/links provided!

I have been on the fence for awhile between the HF+ and the RSPdx.

-- Andy - Arlington TX

If you have a problem with posts, email the moderators.

#15748

If you have a complaint about posts, email the moderators. No one should be taking it into their own hands to decide what is on or off topic and complaining directly to anyone here.

Reply off-list.

--
Steve Greenfield AE7HD

Re: What is your preferred antenna for SWL'ing on a balcony.

Paul Egan

#15746

I built a moebius loop from a couple of 1.2m pieces of RG-8X that I had lying around ( a bit bigger than it should be). I attached a 1:1 balun intended for a dipole also that I had lying around. It's not perfect but it does hear quite well from 6 to 8 Mhz. and I can hear MW stations for the first time on this rtl-sdr v3. Need to look at other frequencies this evening but I'd say it's a pretty good starting point.

Added a cheap aliexpress LNA at the feedpoint and got too much MW + FM signal, as Tom predicted. So I removed it.

I'm tracking aircraft using PC-HFDL and Google Earth (New York on 6661 khz.). There are more on the screen than I've seen before. Some are arriving and departing in NYC and Chicago which I had never noticed before.
40m ham band is very active.

I agree that I need to upgrade the SDR and intend to soon but it's good to see what this little dongle can do.

Thanks again for everyone's input.
73,
Paul VA3ZC

Re: Best SDR Receivers

#15745

Honestly, from everything?I've read here and other forums, for LF, MF and HF you can either choose the AirSpy Discovery HF+ or Perseus.

The only practical diference is seen if you decide adopting techniques and workflow of hard core MW DX folks:

- Perseus allows you to record slices of up to 2MHz, while AirSpy DHF+ can only record slices of 900 KHz.

- Perseus lets you to use Jaguar SDR software, which was specifically tailored for MW DXing and became the standard in the hobby.

- Perseus has better/more numerous traditional band-pass filters. AirSpy DHF+ has fewer filters, but its car-stereo IC (ST Microeletronics?STA709)?uses ?'polyphase mixer' for improve performance*

AHF+ has some advantages on its own:

- powered directly from the USB port (Perseus needs a separate power supply)

- Coverage between 61 and 260MHz, providing a very decent VHF and Broadcast FM receiver (Perseus goes up to 40MHz, 88-108MHz coverage possible if you buy their downconverter)

pu3hag

*?

Show quoted text

On Mon, Jan 3, 2022, 20:33 Everett N4CY via <everettsharp=[email protected]> wrote:

Hi Bob,

How did you add the picture and contact info to your email?

Everett N4CY

On Monday, January 3, 2022, 5:05 PM, Bob Willey K3RLW <bobwilley@...> wrote:
Does anyone have a chart comparing features/price, like sensitivity and other special feataures for the uninformed, so not everyone has to make all the mistakes.
Thanks.

Bob Willey
K3RLW
(410) 251-8960 | K3RLW@...
5161 Ocean Gateway, Trappe Maryland 21673-2023 USA

On Mon, Jan 3, 2022 at 3:55 PM Chris Smolinski <csmolinski@...> wrote:
The AFEDRI SDRs are worth considering as well. Not quite the performance of my RF Space netSDR, but still respectable.

Chris Smolinski, W3HFU
Black Cat Systems
Westminster, MD USA

> On Jan 3, 2022, at 3:50 PM, W0LEV <davearea51a@...> wrote:
>
> Yes, front end overload is a major shortcoming of the SDRPlays.? Not so much so for the AirSpy products.? Yes, the Persus is outstanding and I wish I had one, but not in the cards on a retirement "salary".? Anyone want to contribute one to me??????
>
> Dave - W?LEV
>
> On Mon, Jan 3, 2022 at 8:27 PM Everett N4CY via <everettsharp=[email protected]> wrote:
> If you are going to buy a SDR, buy either a Pereus, or a RFSpace CloudSDR. I have both and they are top of the line. I have had several AirSpys and SDRPlays. The AirSPY is okay, but skips band coverage and the SRPPlay DUO has a very poor receiver. The SDRPlay rspDX is better but the front end overloads.
>?
> Everett N4CY
>
> In a message dated 1/3/2022 1:51:18 PM Central Standard Time, davearea51a@... writes:
>?
> The AirSpy is a far superior product to the SDRPlay.? I have both and several iterations of the AirSpys including the HF+ Discovery.? The SDRPlay sits on the shelf gathering dust.? Spend a bit more and go with the AirSpy products.
>?
> Dave - W?LEV
>
> On Mon, Jan 3, 2022 at 6:58 PM Tom Seeger <thomas.b.seeger@...> wrote:
> Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
> 73 Tom
>?
>?
>
>
> --
> Dave - W?LEV
> Just Let Darwin Work
>
>
>
>
> --
> Dave - W?LEV
> Just Let Darwin Work
>
>

Re: Good Vibrations? / locking compounds

#15744

I have used my daughters finger nail polish as thread locker. Yes it does contain acetone but if used sparingly and on the end of the screw and nut, should not cause a plastic meltdown event. It worked so well, I now have a nail polish collection of my own!

73,
Kevin
kc6pob

On Sunday, January 2, 2022, 10:12:29 PM PST, Fred Moore <n40cla@...> wrote:

Good?morning all.??

I have been following all the comments about vibrations on the antenna causing mounting hardware to loosen.? I have used the following type of hardware for years at commercial sites and can't remember where we have had any hardware loosen up for whatever?reasons.? The attached link below uses one nut and one split ring washer at every point where any tightening is to happen for mounting.? All the big boys, 2 way communication, cell site antennas etc use this type of hardware and once it is up it is never touched again until it has to come down or be moved.? No criticisms intended, just my opinion.

Fred - N4CLA

Show quoted text

On Sun, Jan 2, 2022 at 7:45 PM Leigh Turner <invertech1@...> wrote:

Good fit-for-purpose cautionary advice here Alan....

Leigh
VK5LT

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Alan
Sent: Monday, 3 January 2022 10:50 AM
To: [email protected]
Subject: Re: [loopantennas] Good Vibrations?

I would NEVER USE LOCKING COMPOUND ON PLASTICS. Many locking compounds can destroy plastic parts over time, they are formulated for locking metal part not plastics.? Same goes for some greases. One former employee used locking compound on plastic nuts, cost ?35,000 to replace the parts.

One Italian manufacturer used a grease to ease driving screws into plastic pillars. After a year the pillars disintegrated and cost the manufacturer a lot of money.

73, Alan G8LCO.

Re: Best SDR Receivers

#15742

Does anyone have a chart comparing features/price, like sensitivity and other special feataures for the uninformed, so not everyone has to make all the mistakes.

Thanks.

Bob Willey
K3RLW

(410) 251-8960 | K3RLW@...

5161 Ocean Gateway, Trappe Maryland 21673-2023 USA

Show quoted text

On Mon, Jan 3, 2022 at 3:55 PM Chris Smolinski <csmolinski@...> wrote:

The AFEDRI SDRs are worth considering as well. Not quite the performance of my RF Space netSDR, but still respectable.

Chris Smolinski, W3HFU
Black Cat Systems
Westminster, MD USA

> On Jan 3, 2022, at 3:50 PM, W0LEV <davearea51a@...> wrote:
>
> Yes, front end overload is a major shortcoming of the SDRPlays.? Not so much so for the AirSpy products.? Yes, the Persus is outstanding and I wish I had one, but not in the cards on a retirement "salary".? Anyone want to contribute one to me??????
>
> Dave - W?LEV
>
> On Mon, Jan 3, 2022 at 8:27 PM Everett N4CY via <everettsharp=[email protected]> wrote:
> If you are going to buy a SDR, buy either a Pereus, or a RFSpace CloudSDR. I have both and they are top of the line. I have had several AirSpys and SDRPlays. The AirSPY is okay, but skips band coverage and the SRPPlay DUO has a very poor receiver. The SDRPlay rspDX is better but the front end overloads.
>?
> Everett N4CY
>
> In a message dated 1/3/2022 1:51:18 PM Central Standard Time, davearea51a@... writes:
>?
> The AirSpy is a far superior product to the SDRPlay.? I have both and several iterations of the AirSpys including the HF+ Discovery.? The SDRPlay sits on the shelf gathering dust.? Spend a bit more and go with the AirSpy products.
>?
> Dave - W?LEV
>
> On Mon, Jan 3, 2022 at 6:58 PM Tom Seeger <thomas.b.seeger@...> wrote:
> Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
> 73 Tom
>?
>?
>
>
> --
> Dave - W?LEV
> Just Let Darwin Work
>
>
>
>
> --
> Dave - W?LEV
> Just Let Darwin Work
>
>

Re: Best SDR Receivers

#15741

The AFEDRI SDRs are worth considering as well. Not quite the performance of my RF Space netSDR, but still respectable. 

Chris Smolinski, W3HFU
Black Cat Systems
Westminster, MD USA

Show quoted text

On Jan 3, 2022, at 3:50 PM, W0LEV <davearea51a@...> wrote:

Yes, front end overload is a major shortcoming of the SDRPlays.  Not so much so for the AirSpy products.  Yes, the Persus is outstanding and I wish I had one, but not in the cards on a retirement "salary".  Anyone want to contribute one to me??????

Dave - W?LEV

On Mon, Jan 3, 2022 at 8:27 PM Everett N4CY via groups.io <everettsharp@...> wrote:
If you are going to buy a SDR, buy either a Pereus, or a RFSpace CloudSDR. I have both and they are top of the line. I have had several AirSpys and SDRPlays. The AirSPY is okay, but skips band coverage and the SRPPlay DUO has a very poor receiver. The SDRPlay rspDX is better but the front end overloads.
 
Everett N4CY

In a message dated 1/3/2022 1:51:18 PM Central Standard Time, davearea51a@... writes:
 
The AirSpy is a far superior product to the SDRPlay.  I have both and several iterations of the AirSpys including the HF+ Discovery.  The SDRPlay sits on the shelf gathering dust.  Spend a bit more and go with the AirSpy products.
 
Dave - W?LEV

On Mon, Jan 3, 2022 at 6:58 PM Tom Seeger <thomas.b.seeger@...> wrote:
Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
73 Tom
 
-- 
Dave - W?LEV
Just Let Darwin Work

-- 
Dave - W?LEV
Just Let Darwin Work

Re: Best SDR Receivers

#15740

Yes, front end overload is a major shortcoming of the SDRPlays.? Not so much so for the AirSpy products.? Yes, the Persus is outstanding and I wish I had one, but not in the cards on a retirement "salary".? Anyone want to contribute one to me??????

Dave - W?LEV

Show quoted text

On Mon, Jan 3, 2022 at 8:27 PM Everett N4CY via <everettsharp=[email protected]> wrote:

If you are going to buy a SDR, buy either a Pereus, or a RFSpace CloudSDR. I have both and they are top of the line. I have had several AirSpys and SDRPlays. The AirSPY is okay, but skips band coverage and the SRPPlay DUO has a very poor receiver. The SDRPlay rspDX is better but the front end overloads.

?

Everett N4CY

In a message dated 1/3/2022 1:51:18 PM Central Standard Time, davearea51a@... writes:
?

The AirSpy is a far superior product to the SDRPlay.? I have both and several iterations of the AirSpys including the HF+ Discovery.? The SDRPlay sits on the shelf gathering dust.? Spend a bit more and go with the AirSpy products.

?

Dave - W?LEV

On Mon, Jan 3, 2022 at 6:58 PM Tom Seeger <thomas.b.seeger@...> wrote:

Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
73 Tom
?

?

--

Dave - W?LEV
Just Let Darwin Work

--

Dave - W?LEV

Just Let Darwin Work

Re: Best SDR Receivers

#15739

If you are going to buy a SDR, buy either a Pereus, or a RFSpace CloudSDR. I have both and they are top of the line. I have had several AirSpys and SDRPlays. The AirSPY is okay, but skips band coverage and the SRPPlay DUO has a very poor receiver. The SDRPlay rspDX is better but the front end overloads.

?

Everett N4CY

In a message dated 1/3/2022 1:51:18 PM Central Standard Time, davearea51a@... writes:

?

Show quoted text

The AirSpy is a far superior product to the SDRPlay.? I have both and several iterations of the AirSpys including the HF+ Discovery.? The SDRPlay sits on the shelf gathering dust.? Spend a bit more and go with the AirSpy products.

?

Dave - W?LEV

On Mon, Jan 3, 2022 at 6:58 PM Tom Seeger <thomas.b.seeger@...> wrote:

Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
73 Tom
?

?

--

Dave - W?LEV
Just Let Darwin Work

Re: Is this Wellbrook wide aperture loop faulty?

#15738

Hello Tom,

 Monday, January 3, 2022

 This TS-590S that I have had for donkey's years has been great on LF, both RX and TX, but the start of its ills came when I managed to transmit a kilowatt of RF INTO th RX port. I fixed it but it has since had other issues and now has a fade on RX problem that seems heat related. It's time to put it out to pasture and either buy a new one or something similar. I use a Red Pitaya and pre amp and the Kiwi plus some Softrocks for RX as well as the 590, but only the Red Piataya could be made to TX as well.

Best regards,
 Chris      mailto:chris@...

TCG> Sounds like you are making great progress Chris.

TCG> I doubt that a new TCVR will make much of a difference. Most of
TCG> them will have filtering to reduce sensitivity at LF/MF. This is
TCG> to reduce the likelihood of problems at HF, like spurious breakthrough etc.
TCG> Is there any chance you could borrow a modern rig and prove me wrong?

TCG> Tom G6PZZ

Show quoted text

TCG> -----Original Message-----
TCG> From: [email protected] <[email protected]> On Behalf Of Chris Wilson
TCG> Sent: 03 January 2022 09:34
TCG> To: Alan <[email protected]>
TCG> Subject: Re: [loopantennas] Is this Wellbrook wide aperture loop faulty?

TCG> Hello Alan, Martin et al,

TCG>  Saturday, January 1, 2022

TCG>  People must be getting bored with my saga by now, so I will
TCG> keep it as short as I can. Basically, yesterday lent me the
TCG> opportunity to do some more tests. Running the injector box off a
TCG> 12V accumulator made zero noticeable difference. Running the KIwi
TCG> as well, off my mobile phone 5V power pack made a minute
TCG> difference to overall noise. Disconnecting the coax to the
TCG> antenna at the injector box still left some strong signals.
TCG> Wrapping about 10 turns of the coax out to the loop around  a BIG
TCG> ferrite ring (I have the spec but can't recall it off hand) made a noticeable difference.

TCG> Then I had the idea to wrap the short (2  foot or so) of coax
TCG> from the injector box to the Kiwi as many turns as possible
TCG> around a similar ferrite ring. I think I got about 5 or six turns
TCG> on, the BNC plug limited this. Now THAT made a big difference!

TCG> I am pretty pleased to have persevered and enormously grateful to those who stuck with me.

TCG> Downside is MF / LF amateur digital performance has markedly
TCG> deteriorated. Is it the smaller circumference of the new loop?
TCG> The 30 to 35 or so degrees rotation of the loop form its
TCG> orientation looking down from the sky (plan view)? Originally the
TCG> loop in plan view ran almost east to west, it's now skewed about
TCG> 35 degrees or so anti clockwise and a bit lower overall....


TCG> Testing has been made a bit problematic as my TS-580S which has
TCG> had a hard, no, very hard life, has started to lose sensitivity
TCG> and sometimes goes totally dead on receive. It seems heat
TCG> related, but it's years old and had one incident where I managed
TCG> to shove a kilowatt of LF 137 kHz up the receive antenna port.

TCG>  Needless to say it didn't like it and I amazed and astounded
TCG> myself by managing to repair it with my scope and a sig gen. More
TCG> good luck, strong coffee and a good light source, plus a huge
TCG> taped together print out of the schematic.

TCG>  I think I might treat myself to a newer (if still secondhand)
TCG> rig soon. As an aside what modern transceivers hear well at LF
TCG> and MF and will TX a milliwatt or so on LF and MF to act as an
TCG> exciter, anyone here any experience of anything suitable or
TCG> should I just get a newer TS-590?

TCG> Critical comments welcome: 

TCG> 

TCG> Thanks again everyone.

TCG> Best regards,
TCG>  Chris      mailto:chris@...


A>> Martin

A>> As Andrew said shorting the input is not a good idea and will not do 
A>> what you think it will. Leaving the terminals open will but you need 
A>> to disconnect both terminals.  The amplifier is a Zwischenbasis type, 
A>> as you have plotted in the past the input reacts to the signal source 
A>> impedance. This form of noiseless feedback is the complement to the 
A>> Norton Amplifier where the output impedance is a transformed version 
A>> of the input impedance, here the output impedance hardly matters but 
A>> you get to  optimise the matching to the source over a much wider 
A>> range than a conventional  "dumb" input , it is NOT a virtual earth 
A>> amplifier in the normal sense ( which also goes nuts with a shorted 
A>> input !) but a much cleverer configuration due to Cantz from 1953.

A>> However before disconnecting the loop  I would remove the power to 
A>> the injector then disconnect the coax to the injector. That would 
A>> show what is leaking into to the coax and then what remains after the 
A>> coax is removed. It seems futile to disconnect the loop when you can 
A>> just power it down.

A>> I used a naked ALA100LN until recently, it works very well from LF to 
A>> HF and beyond. The IMD performance is outstanding six miles from 
A>> Brookman's Park. I now use a new arrangement  that drops BP signals 
A>> an additional 30dB. I spot to PSK reporter from a tiny urban back 
A>> garden, Don't do too bad for an antenna 3m high surrounded by 
A>> switchers although BT has blocked 30m very effectively.

A>> 73, Alan G8LCO.















TCG>

Re: What is your preferred antenna for SWL'ing on a balcony.

#15737

The AirSpy is a far superior product to the SDRPlay.? I have both and several iterations of the AirSpys including the HF+ Discovery.? The SDRPlay sits on the shelf gathering dust.? Spend a bit more and go with the AirSpy products.

Dave - W?LEV

Show quoted text

On Mon, Jan 3, 2022 at 6:58 PM Tom Seeger <thomas.b.seeger@...> wrote:

Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
73 Tom

--

Dave - W?LEV

Just Let Darwin Work

Re: What is your preferred antenna for SWL'ing on a balcony.

#15736

Hi Paul. I'd like to save you some grief. I've used the rtl-sdr v3. So I speak from experience. The Youloop was designed to be used with the Airspy HF+ which has very high sensitivity. The rtl-sdr v3 has quite poor sensitivity and using a youloop without an amplifier will leave you disappointed. Since you live in a big city on the 10th floor, just adding a broadband RF amplifier will most likely swamp the rtl-sdr v3 with FM and probably AM signals too. So plan on building or buying a lowpass and maybe a high pass filter as well. This is why I recommended the MLA-30. It contains the filters and an adjustable attenuator. Alternatively as mentioned you might want to spend your dollars on a better SDR that has good built-in bandpass filters like the Airspy or SDRplay.
73 Tom

Re: Is this Wellbrook wide aperture loop faulty?

#15735

Hi Tom

I think most/all  switch the below mw ( hpf)  filter in and out depending upon frequency.. damn sure mine does when tune below 1700khz..above in, below out.otherwise it would be deaf below 1700..

Simon

Re: Is this Wellbrook wide aperture loop faulty?

#15734

Sounds like you are making great progress Chris.

I doubt that a new TCVR will make much of a difference. Most of them will have filtering to reduce sensitivity at LF/MF. This is to reduce the likelihood of problems at HF, like spurious breakthrough etc.
Is there any chance you could borrow a modern rig and prove me wrong?

Tom G6PZZ

Show quoted text

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Chris Wilson
Sent: 03 January 2022 09:34
To: Alan <[email protected]>
Subject: Re: [loopantennas] Is this Wellbrook wide aperture loop faulty?

Hello Alan, Martin et al,

 Saturday, January 1, 2022

 People must be getting bored with my saga by now, so I will keep it as short as I can. Basically, yesterday lent me the opportunity to do some more tests. Running the injector box off a 12V accumulator made zero noticeable difference. Running the KIwi as well, off my mobile phone 5V power pack made a minute difference to overall noise. Disconnecting the coax to the antenna at the injector box still left some strong signals. Wrapping about 10 turns of the coax out to the loop around  a BIG ferrite ring (I have the spec but can't recall it off hand) made a noticeable difference.

Then I had the idea to wrap the short (2  foot or so) of coax from the injector box to the Kiwi as many turns as possible around a similar ferrite ring. I think I got about 5 or six turns on, the BNC plug limited this. Now THAT made a big difference!

I am pretty pleased to have persevered and enormously grateful to those who stuck with me.

Downside is MF / LF amateur digital performance has markedly deteriorated. Is it the smaller circumference of the new loop? The 30 to 35 or so degrees rotation of the loop form its orientation looking down from the sky (plan view)? Originally the loop in plan view ran almost east to west, it's now skewed about 35 degrees or so anti clockwise and a bit lower overall....

Testing has been made a bit problematic as my TS-580S which has had a hard, no, very hard life, has started to lose sensitivity and sometimes goes totally dead on receive. It seems heat related, but it's years old and had one incident where I managed to shove a kilowatt of LF 137 kHz up the receive antenna port.

 Needless to say it didn't like it and I amazed and astounded myself by managing to repair it with my scope and a sig gen. More good luck, strong coffee and a good light source, plus a huge taped together print out of the schematic.

 I think I might treat myself to a newer (if still secondhand) rig soon. As an aside what modern transceivers hear well at LF and MF and will TX a milliwatt or so on LF and MF to act as an exciter, anyone here any experience of anything suitable or should I just get a newer TS-590?

Critical comments welcome: 

Thanks again everyone.

Best regards,
 Chris      mailto:chris@...

A> Martin

A> As Andrew said shorting the input is not a good idea and will not do 
A> what you think it will. Leaving the terminals open will but you need 
A> to disconnect both terminals.  The amplifier is a Zwischenbasis type, 
A> as you have plotted in the past the input reacts to the signal source 
A> impedance. This form of noiseless feedback is the complement to the 
A> Norton Amplifier where the output impedance is a transformed version 
A> of the input impedance, here the output impedance hardly matters but 
A> you get to  optimise the matching to the source over a much wider 
A> range than a conventional  "dumb" input , it is NOT a virtual earth 
A> amplifier in the normal sense ( which also goes nuts with a shorted 
A> input !) but a much cleverer configuration due to Cantz from 1953.

A> However before disconnecting the loop  I would remove the power to 
A> the injector then disconnect the coax to the injector. That would 
A> show what is leaking into to the coax and then what remains after the 
A> coax is removed. It seems futile to disconnect the loop when you can 
A> just power it down.

A> I used a naked ALA100LN until recently, it works very well from LF to 
A> HF and beyond. The IMD performance is outstanding six miles from 
A> Brookman's Park. I now use a new arrangement  that drops BP signals 
A> an additional 30dB. I spot to PSK reporter from a tiny urban back 
A> garden, Don't do too bad for an antenna 3m high surrounded by 
A> switchers although BT has blocked 30m very effectively.

A> 73, Alan G8LCO.

A>

Re: Good Vibrations?

#15733

All noted Andrew, the installation has been a valuable part of my listening arsenal and is weathering well and continues to give a good account of itself.

Re: What is your preferred antenna for SWL'ing on a balcony.

#15732

Happy New Year. My favorite at the moment?is the LZ1AQ active amplifier?configured with two orthogonal loops. I have the you loop but have not had the chance to test it.?

Mike

AB4KJ

Show quoted text

On Sun, Jan 2, 2022 at 5:25 PM Paul Egan <paul@...> wrote:

I have a 10th floor balcony and would like a no tune solution for an rtl-sdr v3 with an upconverter.

I've tried a miniwhip from aliexpress. It was pretty deaf.

The youloop looks interesting but I think it needs a more sensitive SDR and using an LNA with the rtl-sdr v3 only elevates the noise from what I understand.

I have a homebrew magnetic loop for transmitting between 17m and 40m but tuning is cumbersome and I would like to receive below 7Mhz.

So what would you install to get a decent signal from 0.5 to 30Mhz? Some sort of passive loop?

Thanks.

.

Re: Good Vibrations?

#15731

开云体育

A rubber gasket is part of the installation kit for the 1m loops. This is to prevent the threaded metal dome from scuffing the plastic loop box and also it should cushion some of the mechanical stress on the Dome cover. Hence, the fixing nuts should not be over tightened so as the compress the casket too much. However, as already suggested; a further nut can be use as locking nut.

?

Kind regards

?

Andrew Ikin