Wellbrook, Pixel, W6LVP. et.al -- what are the differences?

[KB2GOM]

There are obviously differences in construction, but the key difference seems to be in the amps . . . or am I wrong?

 

[ka3jjz]

'in the amps'? If you mean the amplifier, that does play a big role. Be more scientific with what you are trying to hear and how you will be using it.

Let's take frequency response of 4 different loops

• MFJ-1886 500 Khz-30 Mhz
• Wellbrook ALA 1530 30 khz-30 Mhz
• W6LVP 135 Khz-30 Mhz
• DX Engineering / Pixel Pro-1B 100Khz-30 Mhz (down to 50Khz with reduced specs)

Now if you happen to be someone who wants to play in the basement (in the new LW allocations), the MFJ is out.

Want to go portable? I understand the Pixel needs 24 vdc which might be harder to do. W6LVP has a version that takes 8 AA batteries which is far and away easier to do for portable work

How much noise is produced by the amp itself? Definitely a question to find out. Remember gain isn't really the goal of using a loop - a better signal to noise ratio is. Also consider how well the amp behaves in a strong signal enviornment.

What about signal rejection - how much does the signal get attenuated when the loop isn't pointed in that direction? That's not a characteristic of the amp, more the antenna design. Obviously the higher the rejection the better. This becomes important if you're a MW or LW DXer, but loops can still have some directivity even if you're in the 160 meter band. Keep in mind that above 2 or 3 Mhz, skywave propagation starts to predominate, and a loop can have difficulty nulling one signal from another.

There's much to consider with using a loop. As the old knight in one of the Raiders of the Lost Ark movies once said...

Choose Wisely

Mike

 

[popnokick]

Something that came up in another "loop-related" thread here on RR: Loop user was annoyed by how often the tuning controls on the loop had to be adjusted due to the very narrow bandwidth or the amount of spectrum the loop optimally "sees" when it is tuned. All loops are very narrow in their tuning, but a useful thing to know would be the working bandwidth before re-tuning is required on each of the loops mentioned above.

 

[ka3jjz]

That statement had to do with PASSIVE loops - those that have no amplifier in them. The ones in this thread (ahem) are ACTIVE loops, and these require no tuning at all. They are very broadbanded.

Please don't mix up the two. They work somewhat differently and each has their place in the proper environments.

Mike

 

[KB2GOM]

'in the amps'? If you mean the amplifier, that does play a big role. Be more scientific with what you are trying to hear and how you will be using it.

Let's take frequency response of 4 different loops

• MFJ-1886 500 Khz-30 Mhz
• Wellbrook ALA 1530 30 khz-30 Mhz
• W6LVP 135 Khz-30 Mhz
• DX Engineering / Pixel Pro-1B 100Khz-30 Mhz (down to 50Khz with reduced specs)

Now if you happen to be someone who wants to play in the basement (in the new LW allocations), the MFJ is out.

Want to go portable? I understand the Pixel needs 24 vdc which might be harder to do. W6LVP has a version that takes 8 AA batteries which is far and away easier to do for portable work

How much noise is produced by the amp itself? Definitely a question to find out. Remember gain isn't really the goal of using a loop - a better signal to noise ratio is. Also consider how well the amp behaves in a strong signal enviornment.

What about signal rejection - how much does the signal get attenuated when the loop isn't pointed in that direction? That's not a characteristic of the amp, more the antenna design. Obviously the higher the rejection the better. This becomes important if you're a MW or LW DXer, but loops can still have some directivity even if you're in the 160 meter band. Keep in mind that above 2 or 3 Mhz, skywave propagation starts to predominate, and a loop can have difficulty nulling one signal from another.

There's much to consider with using a loop. As the old knight in one of the Raiders of the Lost Ark movies once said...

Choose Wisely

Mike

Mike, how did you know that was one of my favorite moments in the movie?

Okay. . .

1. No real interest in portable, but AA batteries might be a good thing in a pinch.
2. No interest "the basement." Mainly interested in HF shortwave and utilities (voice)
3. Not really in a strong signal environment (that I know of)
4. How much noise is produced by the amp itself? Definitely a question to find out. Alright, how? (I'm not being an obnot here; I really don't know how to approach the subject.)

 

[ka3jjz]

If the specs on the website don't have it, I'd simply drop an email or do a Google search. Someone may have done a review and had the gear to properly measure it. Larry W6LVP has been quite friendly with folks wanting more information on his loops.

Mike