The Chameleon RXL PRO Gets a New Pre-Amp! (AD
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- Опубликовано: 6 сен 2024
- The Chameleon RXL small receive-only loop gets a new pre-amp. Chameleon sent me the new pre-amp, which I installed, and this complete review compares the RXL with new pre-amp against my venerable MFJ-1886 small receive-only loop with pre-amp
#preamp #receive_only #SWL #SWLantenna #sdrplay #thermalnoise #noise #antenna #chameleon #mfj #mfjenterprises #mfj1886 #bias-tee #biast
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The SDRplay RSPduo provides an excellent method to comparing multiple antennas simultaneously with EXACTLY the same signals, atmospheric noise and interference being received.
True!
Dave, good video. Interesting why a BNC was used for the antenna port, on the pre-amp. Seems like products with BNC connectors are often engineered for portable operation, but not sure that was the premise of its use, in this particular case. 73, AC3HT
I would venture a guess that the cable from BNC connector was supplying power from the bias-t to the preamp and using a BNC was just a good way of preventing user error by crossing a pair of SO-239 connectors.
Wow! This video was very informative. Now I really want to get my MLA-30 up and running.
I have owned a CHA-RXL-Pro for about a year. I have also mounted it on a RCA TV remote rotator that costs about $120. I am indeed very happy with this loop antenna. By simply rotating the antenna from east-west to north-south, I can audibly switch from an AM 530KHz Canadian station to a Cuban station. This to me clearly demonstrates the excellent directional selectivity this loop possesses. However, this antenna has it's caveat. I live in an area where rainy days can cause moisture condensation inside the antenna amp housing that is about 90% empty. After I complained to the manufacturer, they made me feel like I was the only one with that problem. I told them that after I opened the antenna amp housing and found water shorting out the amp. I solved this problem by filling the antenna housing with Epoxy Seal 9000. That epoxy two part compound is made to water proof electronics and it cured my problem. Quite frankly, for what Chameleon charges for the CHA-RXL-PRO ($525), that sealing should have been done at the factory. Other than that disappointment, its a great antenna and I am very happy.
They might have put the BNC on the antenna side of the Bias-T to prevent accidental connection of the power side to the radio.
The antenna itself has an SO-239.
Excellent information Dave. Thank you for sharing your knowledge.
Very good & imformative broadcast - thank you
It should also be noted that the unamplified loops, such as the others Chameleon sells, would potentially work quite well with SDRs because their front ends tend to be very sensitive. In such cases, an amp may not even be needed. An example would be the popular YouLoop, which you can build yourself with some surgery. For cave dwellers (like me), this is probably one of the best ways to go
Strange results to say the least. I have an 18 meter circumference loop with a Wellbrook ALA100LN amplifier in the centre, and the noise floors it is producing are well down from what you measured. OK, there are some differences in time and equipment use on the bands you have tested the loops on, that is normal. Firstly, did you mention with what equipment you made the measurements? I used a Wandel & Goltermann level meter that was calibrated a few months ago and a Perseus SDR that is very accurate. I live in suburbia, and you can be in a city, or you have some industry nearby. Furthermore, I, also feed my Bias-T's with a battery and no longer use PSU's, even linear models. Yes, the SNR is the only measurement of value for me also. Have been using loops for many decades and still have a number of the small models like the ones you used. Bottom line, the resulting noise floors are too high for these model of active loops. The use of decent low noise transistors can be of help. Look at the Wellbrook designs, these designs were always on top of the game for many years. Also, Hans Stampfl makes nice amplifiers that have low noise and good gain. 73" ;-)
New to radio and learning….so I am interested in loop antennas, looking at a mag loop for HF work. And I know Chameleon and Alpha both offer mag loops that have a 2nd section of coax you can add to allow work on 60 and 80 meter bands. It is parallel to the loop as it is installed.
What I am curious about is if a 2nd loop was added that was 90 degrees to the other so as to eliminate the need for rotating the antenna? Or is it best to put it up as a horizontal loop?
I miss the non-pro version. With 2 section loop!
Very good and interesting video. Many thanks Dave...
Hello Dave, I want to step up my game and build from scratch a directional antenna for 40meter . I have dipoles , beverage and a couple of others, what do you think is the best way to tackle this project height and room are not a problem . Any suggestions on material vendors is welcome
Take a look at phased verticals. You'll need four plus the phasing box. Contact DXEngineering--they'll help you.
How can you tell when shopping for this antenna if the preamp is the new one or the old one?
The new one is a CHA RXL PRO
@@Nath4n1977 yes - we’ll update our website accordingly next week for that option.
Dave - I just bought one of these to use as a listen antenna (to be plugged into the Antenna 3 (RX only) on my Yaesu 3000. My transmit antenna is a fan dipole. I am concerned that if I transmit at 500W, it will harm the preamp (I have the new one). I can't move it any further away than about 20 feet due to the layout on my roof. I have been told by Don at Chameleon that the new preamp is more tolerant to nearby RF but wasn't able to answer my question as to whether I can use my linear amp. What is your experience? Also, it seems to pick up a lot more noise when mounted vertically, so he suggested mounting it horizontally...in which case I wouldn't need a rotator. Your thoughts? Thanks! Bob KJ6GEU
Important to note that some of the preamps do not work well at LF. The MLA-30+ is good for HF, but is not good at lower frequencies (ie no good for NDB hunting, not sure about MW DXing).
I find my MLA30 very good for MW DXing, the null is extremely sharp, I am able to completely null a 20 mile local here and hear a DX station clearly on the same frequency at night. Use the null to direction find ground wave signals as the receive lobe is fairly broad
@@dave10524yeah fake lie. That's not how loops actually perform.
So, can two loops stacked and oriented orthogonal to each other give 360° coverage? How would they bebe connected?
If you mount the receive loop horizontally will it give you 360 receive performance?
Yes
I don't think these antennas were properly installed at all. Loops like these tend to perform better when closer to the ground. Some say no more than 1 loop diameter above ground, others say around 8-10 foot or so. Mount them too high and they start to lose their directional capabilities and become more skywave sensitive. 20 foot is just too high. Mounting them close to the ground is also what makes them HOA busters because they can be more easily hidden from view. You might want to consider doing your reviews with this in mind. Also it should be noted that their directional characteristics tend to die off around 2-3 Mhz or so, depending on the loop design. There is a lot of material out there, including the late Joe Carr's books on the subject of loops.
The rule of 1 loop diameter above ground only apply to radiating loop. Receiving loops will get better with hight.