Category Archives: Antennas

Using the Icom IC-705 to record a local AM broadcast station

In my previous post, I mentioned how much I enjoy the built-in digital audio recorder in the new Icom IC-705. While I wouldn’t buy a QRP transceiver specifically for built-in audio recording–there are less expensive options out there–it is an incredibly useful feature in my world.

After publishing that post, I was reminded that Monday morning (October 12, 2020) I connected the IC-705 to my homebrew Noise-Cancelling Passive Loop antenna mounted indoors at my parents’ house.

My NCPL antenna

Their house is like so many others in that it is inundated with RFI (radio frequency interference). I find that the NCPL antenna does a fine job mitigating most of that noise on the mediumwave band when I position it so that the bulk of the interference is nulled.

Monday morning, I tuned the IC-705 to my favorite local AM station: WAIZ on 630 kHz.

Weekday mornings, Dave and his “Wacky Wake-Up Crew” always put me in the right mood. They’re incredibly goofy/corny and 100% original.

It’s extraordinarily rare these days to find a local radio station, with local talent, creating a local daily radio show. Almost all of their ads are local, too.

I made the following off-air recording for myself, but decided to upload it for others to enjoy. I’m not sure what the receiver audio EQ or bandwidth filter was set to when I recorded this. It’s not a demo of receiver performance, just a little radio fun.

Enjoy:

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Tecsun PL-990 Hidden Feature: Toggling ferrite bar and telescopic whip antenna on MW & LW bands

Many thanks to Anna at Anon-Co who recently shared an interesting “hidden feature” of the Tecsun PL-990 which allows the user to toggle between the internal ferrite antenna and telescoping whip antenna while on either the mediumwave or logwave bands.

Procedure:

1) Turn on the radio and then select either the MW or LW frequency band.

2) Press and hold the [ 3 ] key for about 2 seconds.

When the display shows “CH-5” (actually an “S” which stands for shortwave telescopic antenna) the radio is now set to MW/LW reception using the telescopic whip antenna.

The display will show MW (or LW) and SW on the left side of the screen.

3) Press and hold the [ 3 ] key for about 2 seconds.

When the display shows “CH-A” (“A” stands for “AM”) the radio is now set to MW/LW reception using the internal ferrite antenna once again.

The display will also show only MW (or LW) on the left side of the screen.

Pressing and holding the [ 3] key essentially toggles between these two antenna settings.

I’ve actually found that, indoors, using the whip antenna on mediumwave has been more effective at mitigating RFI with strong local stations. The ferrite bar antenna has more gain, of course, but for locals it’s not necessarily needed.

Many thanks, Anna, for sharing this tip!

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How to build an automatic remote antenna switch


Many thanks to SWLing Post contributor, Kostas (SV3ORA), for sharing the following guest post which originally appeared on his radio website:


How to build an automatic rig/antenna switching system

by Kostas (SV3ORA)

When I started collecting vintage rigs, I ended up in a line of rigs on my bench, that were sitting there, disconnected from any mains cables or the antenna. I wanted these rigs to be ready to fire at any time I wanted to, without having to connect/disconnect cables all the time. I also wanted to be able to compare different rigs performances at the flip of a switch, which is the only way this can be done on the HF quick fading conditions. For power cables, the solution was to leave them connected in the mains plugs all the time. My rigs that have an internal PSU, have mechanical switches, so they are isolated from the mains when they are switched off. The rigs that are powered by an external PSU, depend on the external PSU main switch for isolation (in case they haven’t mechanical switches on them), which in my case is mechanical and switches off the mains power, when the PSU is switched off.

However, for the RF cables, this was a different story. Having only one antenna and multiple rigs, means that you have to connect each rig to the antenna every time you want to operate each rig. This is not only boring and time consuming (you have to reach the back of the transceivers to connect/disconnect the connectors), but eventually causes the connectors of the coaxial cable and the rigs to wear out. I decided to make things better and make an RF rig selector for my rigs. This RF rig selector has been described in this link.

The current antenna I use is fine for transmitting, but in the noisy neighbourhood where I live, it picks up a lot of noise. I have tried many solutions, without significant effect in the noise level. This is why I decided to use a separate antenna for receiving, from that used for transmitting. This antenna will be some kind of loop probably, so as to be immune to noise or insensitive to the direction of the noise. It will be placed in a different location than the transmitting antenna, a location which will be less noisy. Unfortunately, the space I have for the TX antenna lies in a very noisy location in my property. So a separate RX antenna, in another physical location is a must. This means that a separate coaxial for the RX antenna must be used. Thankfully, the RX coaxial can be very small in diameter, passing easily through the sides of the windows, without extra holes.

To satisfy all of my requirements, I developed the circuit shown above. The circuit is able to switch a common antenna to four different rigs. Why four? Because this was the capacity of my switch and the number of connectors I had available. If you have a greater capacity switch and more connectors, expand the circuit to your needs.

The circuit of the shack switch, allows for 4 separate rigs to be selected, and two antennas, one for RX and one for TX. TX/RX antenna selection is being done automatically (split antenna operation) and controlled by the PTT of any of the rigs connected. This feature can be bypassed by the switch, so that the TX antenna can be used for both RX and TX. The same switch allows also RX operation with passive RX antennas of active ones. When in the active RX antenna position, power is passed to the remote RX preamplifier through the RX coaxial cable, using a bias-T circuit. The values of the bias-T circuit have been chosen very large, so as active RX antennas that operate at LF and lower could still be used. The RF relay defaults in the TX antenna, so that if there is a power failure, or if the circuit is not supplied with power, you can still receive (and transmit) with the TX antenna. The other way around, would be fatal for both the transceiver and the RX antenna (If you transmitted accidentally into it).

The PTT circuits are based on my transceivers. Unfortunately, there is no “standard” for the PTT circuits, each rig has its own way, so the PTT circuits must be thought for each of them. I followed an “inhibit” approach for the PTTs. That is, all the PTT switches are connected in series and DC is passed through them. If any of the rigs transmits, the PTT switch is opened and the circuit switches to the TX antenna. For the rigs that do not have an internal relay but output DC on TX instead, an additional small relay is used (for greater isolation and lossless switching). The only drawback of this “inhibit” topology is that the PTTs of all the rigs must be connected to the circuit simultaneously. If you want to exclude a rig of course, you may short circuit it’s PTT connector in the circuit. The PTT circuits as I said, are non-standard, so you might want to change the circuit to your needs, but anyway you got the idea.

Notice the connections in the circuit. One section of the RF switch (on the left) is used for the positive wire (central conductor of the coaxial) and another for the negative (braid of the coaxial). Why is that? This is because I canted to add a special feature to the switch. That is, the ability to disconnect the antenna from any rig when the rigs are not used. Previously, I used to disconnect the antenna coaxial from the transceiver when I was away, so as to protect the transceiver from antenna static discharges and possibly destroy it’s front end circuits. Now, with a single flip of the switch, I am able to do so. Because I wanted the switch to operate on different types of antennas (balanced or not) I decided to short circuit both poles of the antenna at this position, to equalize their charges.

But equalizing their charges was not enough. I had to find a way to let these charges go to the ground, so that the antenna is discharged. Directly grounding the short circuit, did not seem a good thing to do, because the whole TX wire antenna on the roof would be grounded. Whether this is a good idea to avoid lightings or not, I do not know. So I decided to keep the short circuited antenna floating and instantly discharge it only when adequate static charge is built upon it. For this purpose, I used a neon tube, permanently connected to the switch NC (not-connected) position. When the switch is in the non-connected position, the tube lights up and discharges the antenna (both poles) if an appropriate amount of static charges has been built upon it. When the switch is in any of the selected rigs connections, the tube is disconnected, preventing it from lighting up when you transmit into the antenna. Note that this configuration, requires that the output (antennas) coaxial connectors must be isolated from the metal chassis of the RF switch!

Isolation of the output antenna connectors has been done with a PVC sheet and isolated screw rings. Also note the usage of BNC connectors on TX and SMA on RX. I used BNC connectors for various reasons. They are excellent connectors with quick lock/unlock features. You do not need to screw them (and wear them out) and once fit in place they are not unscrewed. Once fitted in place, they allow for rotating the connection without unscrewing the cable or bending it. They can handle 100W easily. Despite all these features, they are much smaller in size and lighter. Their reduced size fits easily to reduced diameter cables like the RG-58 and similar. In an RF switch where there are lots of cables connected, this does make a difference. They are also very common and very cheap. There are even types that do not require soldering at all to fit a coaxial to them. I use BNC connectors even at my antenna side, as they have been proven to be quite waterproof. The types of BNC connectors I choose are not silver plated. Despite silver plated connectors are better, in the long term they are corroded by humidity and become much worst than the nickel plated connectors. The connectors I used are nickel plated with gold plated central conductors. I have found these types to be much more durable over the years, despite being cheaper. The same goes for the RX SMA connector, but I used an SMA connector there so as to accommodate thinner coaxial cables for RX.

The BNC connectors used, are the square flange types. I used this type of connectors because when they are fitted onto the chassis, they cannot be unscrewed, unlike the single-hole types. For the RX though, I used an SMA connector because it is even smaller and it can accommodate smaller diameter cables. The coaxial cable used for the internal switch connections on TX, is the RG-223. This cable is silver-plated (both the central conductor and the braid), it has double braid for increased shielding, it is of the same diameter as the RG-58 and it has a bit lower loss. The cable loss is negligible though for such small pieces of cable. The same type of cable has been used for the internal switch-relay connections as well as for the connections of the selector to the rigs. Appropriate lengths of RG-223 cables were cut and fitted with BNC connectors at one side and the appropriate rig connectors at their other side. For the RX antenna, you may use the thinner diameter cable you can find. I used a small piece of very thin coaxial (taken out of the WiFi card of an old laptop) and passed this piece through the side of the windows of the shack and through the mosquito net of the windows. No extra holes are required that way! For the rest of the RX cable, you can use whatever cable diameter you want, but I tried to use the smallest diameter I could find, so that the cable is as much phantom as possible.

All the coaxial rig cables are grounded at the connectors side. I used a piece of coaxial braid and fitted it to the connectors screws. Then I soldered the braids of the coaxial cables onto this piece. Notice the black ring screw isolators at the antenna connector, to isolate it from the chassis. Speaking about the chassis, do not use a plastic chassis for the RF switch, use only a metal one! The picture below, as well as all the next pictures, show the RF cables arrangement, but note that the circuit in these pictures is not complete yet.

The coaxial cables are soldered onto the switch contacts. Where a ground connection is required, a piece of braid accomplishes this. Do not use thin wires, the device has to allow for at least 100W of HF RF power to pass through it. I have tested the switch with 200W of power and there were no problems at all. The neon tube directly connects to the appropriate switch contact and to the chassis.

The most important part of an RF switch is of course the switch itself. For 100W of HF RF power, I would suggest you to use a porcelain switch. I had a 5-positions 4-sections small porcelain switch, which I used. I connected two sections at each side in parallel (adjacent pins connected together). That is, two sections in parallel for the positive wire and two sections in parallel for the braid. I did that for various reasons. First, by using two contacts for each connection instead of one, you increase the power handling capability of the switch. Then, you ensure a sure-contact throughout the years. Any corrosion or wearing on the switch contacts would cause contact problems eventually. By using two contacts for each connection instead of one, you double the probability for a good contact. After all, I had a switch with more sections, so why not make a good use of them?

The completed selector is shown above. The relay was been taken out of an old CB radio. Use the best quality relay you can afford, as this will be switched quite often and it must handle at least 100W of RF power.

The results from the RF switch operation are quite satisfying. The overall construction is kept small and low profile. The switch makes a good contact despite being small. The automatic discharger seems to work well. On receive, there is some RF leakage, as I expected, in the near by cables, which is noticed in the higher HF bands or in very strong signals. The very sensitive receivers we use, are able to detect that. This RF leakage occurs even when the switch is in the NC position, where the antenna is disconnected and floating. So, to be honest I have not figured out if the leakage is from the switch or from the external cables in the shack. On TX, there is of course severe leakage from the transmitting coaxial to the rest of the ports. This IS expected. There is leakage even without using any selector at all, in the nearby receivers, when a transmitter operates at such high powers. There is nothing you can do about it really, unless your receiver has a mute capability, which I did not bother to take care of.

The TX/RX switching is taken care automatically and this is very useful and relaxing for the operator as he does not have to worry about anything. The active or passive RX antenna selector and the feature to disable the auxiliary RX antenna are really useful and you can do many antenna and rigs comparisons on-the-fly with it, by the flip of a switch. Depended on the noise level and the sensitivity you want to achieve, the switch will provide you the most optimal RX conditions instantly!

The most important thing though, is that the goal of this project was achieved. I am able to switch the antenna to whatever rig I want at the flip of a switch. And before I go away, at the flip of a switch I can isolate and automatically discharge the antenna when needed. This is so much more convenient than having to connect and disconnect cables all the time. I can also now use a separate antenna for RX, which greatly improves reception in my case. This antenna is automatically switched by any rig I have and I do not have to worry about anything. I can also do comparisons between different antennas on RX, which is crucial in deciding which antenna is better for receiving. All these features make this little simple to build circuit, so useful and an integral part of the shack.


Thank you for sharing this practical and affordable project with us, Kostas!

Post Readers: Check out this project and numerous others on Kostas’ excellent website.

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Gary DeBock experiments with FSL antenna nulling to eliminate a “pest” station

Many thanks to SWLing Post contributor and Ultralight DX enthusiast, Gary DeBock, for sharing the following guest post:

Nulling a local pest with dual FSL Loops

by Gary DeBock

After many dual FSL antenna experiments I’ve finally determined how to effectively cancel out QRM from a local pest that is off to the side (ideally 90 degrees different, but practical from 50 degrees to 90 degrees different) from a weak DX station, although I’m not quite sure of the theory behind this discovery.

This experiment was an attempt to cancel out QRM from a local pest, 950-KJR in Seattle, WA (35 miles/ 56 km to the north) and chase 950-KKSE in Parker, CO (1005 miles/ 1617 km to the southeast) during the early morning hours. The receiver was a basic (non-SSB) C.Crane Skywave, and two identical 5 inch ferrite rod FSL antennas were used. Please refer to the photo (above) to follow this description.

Step 1) Null out the pest station with the portable radio’s loopstick (away from the FSL antennas). Set the radio down in this nulled position, so that the pest station is as weak as possible, while ensuring that there is space to set up the FSL antennas to the back and side (see photo).

Step 2) Take the “Reception FSL” and use it to peak the pest station’s frequency, setting it up parallel to the portable radio as shown, at the position providing the maximum inductive coupling gain. This will temporarily boost up the pest station, which previously was nulled.

Step 3) Take the “Nulling FSL” and pretune the frequency to that of the pest station. You can do this either by adjusting the variable cap plates to match those of the “Reception FSL,” or by temporarily peaking the pest station’s signal in a position in front of the portable radio. After setting this frequency, set the “Nulling FSL” off to the side of the portable radio as shown, with the spacing identical to the spacing between the radio and the “Reception FSL.”

Step 4) Slowly and carefully tune the “Nulling FSL” until you hear the pest station’s signal take a sharp drop. This setting will be very sharp, but once you find this position you will have nulled out the pest very effectively, and if another station is on the frequency, it may suddenly become dominant, even if it is far away (like 950-KKSE in Denver).

Some MP3’s from this morning’s experiments:

950-KJR in nulled position with the portable only

950-KKSE generally dominant over the local pest KJR when the “Nulling FSL” is peaked


Fascinating, Gary! I don’t understand the dynamics of why this works, but it’s amazing that it does so effectively. I can think of two MW frequencies in particular where I could put a system like this to the test. 

Thank you for sharing!

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Majority of YouLoops listed on eBay are not an Airspy product

Many thanks to SWLing Post contributor, Chris Smolinski, who shared the screen shot above of a “YouLoop” being sold by a vendor on eBay.

While the Airspy YouLoop is based on a public domain noise-cancelling passive loop design that dates back decades (a.k.a. the Moebius loop antenna) buyers should note that many of the “YouLoop” antennas on eBay are not manufactured by Airspy. The product titles are misleading in this regard:

The RTL-SDR Blog does sell the original Airspy YouLoops on eBay for $34.95 shipped (and, as you can see above, they seem to pop up first in the search results).

Many of the other loops being marketed as “YouLoops” on eBay cost around $23.00-25.00 shipped. About $10 less, but there’s no guarantee the toroid windings, for example, will have the same specs as the original YouLoop.

It’s easy to spot the YouLoop copies because the cross over and toroid enclosures are much larger than those of the authentic AirSpy YouLoop:

Compared with the Airspy YouLoop:

Airspy doesn’t own a patent for the YouLoop (indeed, they even suggest homebrewing one) so this isn’t a clone. Rather, buyers should simply be aware that, as far as I know, the only authentic new YouLoops are being sold on eBay by the RTL-SDR blog.

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CHA MPAS Lite: Chameleon designs a new compact portable antenna system

Many thanks to SWLing Post contributor, Don, who notes that Chameleon Antenna has just introduced the CHA MPAS Lite: a modular portable antennas system covering from 6M – 160 meters.

I know a number of participants in the Parks On The Air program who use the CHA MPAS antenna system–the MPAS Lite is the “little brother” of that antenna, according to Chameleon.

Although designed with the new Icom IC-705 and other QRP transceivers in mind, the CHA MPAS Lite can handle up to 100 watts in SSB or 50 watts in CW.

They plan to start shipping the antenna in early November 2020 and the price for the system is $340.00. That may sound like a lot of money for an antenna (it is, let’s face it!) but if you speak with pretty much anyone who owns a Chameleon antenna they’ll tell you it’s worth it. The quality is second to none. I’ve been testing their Emcomm III wire antenna recently and it must be one of the most robust portable wire antenna systems I’ve ever evaluated.

Also, all of their products are designed and manufactured in the USA.

Click here to check out the CHA MPAS Lite product page.

We recently added Chameleon Antenna to our list of sponsors here on the SWLing Post. I’m very proud to include them because one of my personal missions is to promote mom-and-pop companies that push innovation here in our radio world! It’s humbling that they support us too.

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Taking the Par EndFedz EFT-MTR triband antenna to the field!

The Par EndFedz EFT-MTR triband (40/30/20M) antenna

In July, I purchased a tiny QRP transceiver I’ve always wanted: the LnR Precision MTR-3B. It’s a genius, purpose-built little radio and a lot of fun to operate in the field.

It’s also rather bare-bones, only including a specific feature set built around ultra-portable CW operation.

While the MTR-3B has features like CW memory keying, a wide operating voltage (6-12 VDC), extremely low operating current (20 ma in receive), real-time 24 hour clock, and a full compliment of keying adjustments, it lacks other features like a volume control, SWR meter, speaker, and built-in antenna tuner.

Some of those may seem like big omissions but SOTA and POTA activators who like extremely lightweight/portable gear love the MTR-3B for being so purpose-built.

The MTR-3B (and its predecessors) operate on three bands: 40, 30, and 20 meters. These are, without a doubt, my favorite bands when operating portable since antenna lengths are reasonable.

Since the MTR-3B doesn’t have an internal ATU, you need to pack an external tuner or, better yet, a resonant antenna–ideally, one that can be used on all three bands.

Although many of my portable transceivers have built-in ATUs, I rarely use them because I primarily operate with resonant antennas. Resonant antennas are more efficient–giving you the maximum mileage per watt. In addition, they’re also more simple: connect them to the rig and hop on the air. No tuner or tuning required.

Since I keep self-contained field radio kits, my MTR-3B needed a dedicated resonant antenna.

The EFT Trail-Friendly antenna is incredibly compact and quite easy to deploy.

I’ve mentioned in previous posts that I’m a big fan of the Par EndFedz Trail-friendly EFT tri-band antenna (above) which is resonant on 40, 20, and 10 meters.  I’ve activated well over 130 parks with this little antenna.

After I took delivery of the MTR-3B, I borrowed the Trail-friendly EFT antenna from my KX2 field kit. It worked well on 40 and 20 meters, but it doesn’t cover the 30 meter band. Also, by borrowing the EFT from the KX2 kit, I broke one of my rules: never borrow from one field kit to feed another. This led to me leaving the EFT hanging in a tree at a remote park and returning a week later–a three hour round-trip(!!!)–to retrieve it. (FYI, in all fairness, I also blamed my trusty canine companion for this mishap!)

Enter the Par EndFedz EFT-MTR triband antenna

A few months ago, Vibroplex purchased the Par antenna line from LnR Precision.

I was very pleased with this decision as I’m guessing LnR Precision wanted to hand off antenna production so they could focus on the very popular Mountain Topper transceiver line.

Vibroplex is owned by my buddy, Scott Robbins (W4PA), who is not only a successful entrepreneur, but also an award-winning contester and DXer. I’ve known Scott for years and knew he’d not only be a great steward of the Par product line, but also push new innovations.

I emailed Scott asking if Vibroplex had a field-portable antenna that would be resonant on 40, 30, and 20 meters. Turns out, there’s a Par antenna designed specifically to pair with the MTR-3 series transceivers: the Par EndFedz EFT-MTR.

Scott pointed me to a description of the antenna on the Vibroplex website:

The new EndFedz ® EFT-MTR is a 40m/30m/20m tri-band QRP antenna rated up to 25 watts. The “MTR” name was selected as LNR Precision developed this antenna to be the perfect companion to the wildly popular 40/30/20m Mountain Topper QRP transceiver. The EFT-MTR’s total length is 65′ of 22 AWG polystealth wire and weighs less than 4 ounces! It is built with the same high level of workmanship and quality that you have come to expect with all EndFedz ® antennas.

A particular innovation on this antenna: This EndFedz is a little different than previous designs. The user has the option to remove an SMA connector at the end of the 30M resonator to enable just 30 meters, or keep the SMA installed for 40 and 20 meters. Because of the broad bandwidth of the antenna, it is unlikely that it will require tuning in the vast majority of deployments. This is particularly true of 30 meters where the band is very narrow. As our tagline states, “They Just Work!”

Included with the EFT-MTR is the EndFedz Antenna Winder. Conveniently allowing winding up the antenna line to not have a tangled mess at the end. The winder will hold both the antenna and 25 feet of RG-174U coaxial cable (optional accessory).

Scott offered to send me an EFT-MTR to evaluate in the field (disclaimer: at no cost to me) and I accepted without hesitation, of course!

An EFT-MTR field review

I’ve taken the EFT-MTR antenna to three park activations at this point and have formed some opinions about it.

The EFT-MTR fits perfectly in a slide-in pocket in the main compartment of the Boot Boss.

First of all, I couldn’t be more pleased with the size as it fits perfectly in my MTR-3B field kit built around my Red Oxx Booty Boss pack.

I really like the built-in antenna winder: it’s larger than that of the EFT Trail-Friendly, but also much easier to wind up and manage post-activation.

I’ll admit, the length of the EFT-MTR was a bit surprising the first time I deployed it: 65 feet.  Keep in mind, though, I had been used to a much shorter 41 foot radiator on the EFT Trail-friendly. Occasionally, I operate in spots where I simply don’t have the room to deploy a long antenna. I also worried that the EFT-MTR resonance might be negatively affected by winding its way through trees and over a branches. The MTR-3B transceiver does not like high SWR values and has no built-in SWR meter to monitor it. Last thing I wanted to do was harm the MTR finals.

You might be able to spot the feed point of the EFT-MTR at my activation of K-6952 this week.

Fortunately, winding its way through trees doesn’t seem to have a significant impact on SWR.

Each time I’ve taken the EFT-MTR to the field, I’ve also taken my KX2 which I’ve used to read the antenna’s SWR value. So far, the difference has only been negligible and SWR well within the tolerances of the MTR-3B.  Score!

I should note here that since I’ve started using an arborist throw line, I’m also able to hang antennas much higher than I could before. This has had a huge impact on all of my field activities.

Removing the SMA cap changes the EFT-MTR from a 40/20 to a 30 meter resonant antenna.

To be resonant on 40, 20 and 30 meters, the EFT-MTR requires a field modification. On the coil about 2/3 the way up the antenna, there’s an SMA connector with a small screw on cap (see above). When the cap is on (thus completing the connection) the antenna is resonant on 40 and 20 meters. You must remove the cap for it to be resonant on 30 meters.

Since I’ve been using the EFT-MTR, I start an activation on 40 meters (which is typically my most productive band), then move to 20 meters (typically, my least productive). If I have the time, or need the extra contacts to confirm a valid activation, I lower the antenna, unscrew the SMA cap, and raise the antenna again.

I thought at first this would be a major pain, but it hasn’t. Now that I’m using an arborist throw line, it’s super easy to lower and raise antennas. But even when I’ve used fishing line, it really hasn’t been an issue.

The only issue I see is I’m afraid I’m going to lose that little SMA cap in the field. To prevent this, I’ve made it a routine to immediately put it in the internal zippered compartment of the Booty Boss pack. I might find a source for those caps, though, just in case I still lose this one.

I’ve been very pleased with the EFT-MTR’s performance. I’m guessing it’s actually higher gain than my beloved EFT Trail-Friendly antenna. On my last activation with the EFT-MTR, I knocked out eight 40 meter contacts in about eight minutes during a period of poor propagation. Note that the MTR-3B was only pushing 3 or 4 watts of power.

I then moved to 20 meters where, frankly, propagation was so crappy I didn’t hang out there long. Instead, I lowered the antenna, removed the SMA cap, and started calling on 30 meters. Within a few minutes, I racked up the rest of my contacts.

I was very pleased with how quickly the Reverse Beacon Network picked up my CQs and was thus auto-spotted on the POTA website.

Conclusion?

If you own a Mountain Topper MTR-3 series transceiver, I highly recommend the EFT-MTR antenna. As with my EFT Trail-friendly and Par sloper, the quality is top-shelf. I expect the EFT-MTR will last even longer than the EFT Trail-friendly since the winder is so accommodating and the in-line coil is designed so that it doesn’t snag on branches as easily.

I’m looking forward to much more field fun with the MTR-3B and EFT-MTR combo!

Click here to check out the EFT-MTR at Vibroplex.

Click here to check out Vibroplex’s full line of antennas.

Many thanks again to Scott at Vibroplex for sending me the EFT-MTR for evaluation!

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