MTR-4B V2.3


Update: 9/1/23: MTR4 V2.3 ordering open for 25 units. Our plan to release in batches of 25 on or about the first of the month where we hopefully can reduce lead times between order and shipment. As we are a small company, hand fabricate and test each unit, we effectively can build one unit/per day or 25/month. With this plan, we hope to keep the radios available for purchase (albeit on a smaller scale) year-round. If the Mountain Topper MTR4 V2.3 shows up on our site as Out of Stock, it means that we are out and will have more available at the beginning of the next month.

Anticipated lead times on shipment within 2 weeks of order.




MTR4b v2.3

Price $369.99. 

“The Mountain Topper”

The LnR Precision MTR transceivers are designed to be efficient portable CW rigs. Whether climbing a mountain and operating SOTA or just out for an afternoon in the park, the MTR’s small size, light weight and meager battery requirements makes it a great choice for these activities. 


  • Side tone Frequency Adjustment (New in version 2.3)
  • Side tone Volume Adjustment (New in version 2.3)
  • Improved access to coin battery (New in version 2.3)
  • Red Gloss enclosure (New in version 2.3)
  • Four bands – 80M, 40M, 30M and 20M
  • Very low receiver noise floor
  • Low current for maximum battery life
  • Wide operating voltage range – 5.5V to 13V
  • Full 5W “QRP” gallon with 12.0 Volt supply
  • 2 line, back lighted LCD display
  • SWR – RF Power display
  • Built in Real Time Clock
  • Internal Iambic B mode keyer, 5 to 31 WPM in 1 WMP increments.
  • Three Morse message memories with beacon mode.


  • 80 meter, 40 meter, 30 meter and 20 meter operation.
  • Receiver sensitivity : ~ 0.5 uV
  • Receiver audio bandwidth: ~ 400 Hz centered at 600 Hz.
  • Receiver current: ~ 27 ma
  • Transmit output power: 5 watts typical at 12.0 Volt input
  • Transmit current: 750 ma Max with 5 watt output
  • Transmit spurious outputs: -50 dBc or better
  • Supply voltage 5.5 volts minimum, 13 volts maximum. 6 to 12 recommended.
  • Antenna Jack: BNC
  • Power Jack: 5.5mm with 2.5mm pin

Dimensions: 5.150″ Length x 3.0″ Wide x 1.075″ Thick
Weight: 7.95 oz

Power supply options:

The MTR-4B V2.3 is designed to put out about 5 watts with a 12.0 V supply. This makes it a good match  to a 3S Li-ion pack which produces a bit over 12V when fully charged. 

A 2S pack can also be used, with reduced power output. But also with reduced transmit current draw, which will extend battery life. Operation is possible down to the minimum discharge voltage for the cells, about 6V, and still produce over 1 Watt of output power.

A 4S pack produces a bit too much voltage to safely power the rig, but a low dropout regulator can be added to bring the voltage down to one more suitable for the rig.

A 9V smoke alarm battery (once used in transistor radios) can power the MTR-4B for several hours. A tad expensive to do regularly though. But it is fun to see how many contacts you can make using one during a contest sprint.  A 9 or 12V battery pack made of AA cells is more long lasting.

A 13.8V bench supply can be used, but this will bring the output power up to 6 to 7 watts. This is fine so long as the SWR is low. At 7 watts, the transmit current is near the maximum the PA FETs can handle and near the point at which the resettable internal fuse will trip (1 A). A high SWR will increase the current in the PA and either trip the fuse or damage the PA.

A simple way of making a 13.8V supply safe to use is to add two silicon rectifier diodes in series with the positive power lead, such as 1N4001 diodes.  This will drop the supply voltage to the MTR by about 1.5 volts.




MTR3B_LCD (Production run ended 8/20)
Shown Below

New Mountain Topper redefines Portable CW with a gorgeous LCD screen in a small lightweight enclosure! 

The Mountain Topper Rigs are designed to be a very small, light weight, very battery efficient, multi-band CW rig suitable for field operation. The small size and low weight make this rig ideal for SOTA operators and backpackers.


  • 3 band operation – 40/30/20
  • Wide power supply operation – 6V to 12V
  • Low operating current – 20 ma @ 6V, 15 ma @ 12V
  • 5+ Watts out at 12V supply, 2.5-3W at 9V supply
  • Easy to read 2 line LCD display with back lighting
  • Push button tuning and audio limiting eliminates protruding knobs
  • Iambic B mode keyer, 9 to 31 WPM range in 1 WPM steps
  • Three, 63 character message memories with beacon mode
  • Optional decoding and display of Morse being sent via paddle. Know you are sending good code
  • Built in 24 hour real time clock
  • Battery back up restores last used settings on power up

Production Run Complete

Click HERE for more details


MTR5B (11/1/21): Production run complete. Considered re-release in 2022 but with the updated design work of the MTR4b version 2.3, it will essentially replace the 5b. The 4b is smaller, weighs less and has an updated design. We may consider alternative bands for the 4b in future years.

MTR3b_LCD (8/28/20): We have completed the current production run of the massively popular MTR3b_LCD. The newly re-design of the MTR4b (version 2) contains all the features of the MTR3b_LCD plus additional functions so in many ways it will serve as a replacement of the 3b. However, we acknowledge the lower price point and slightly smaller enclosure. We are considering another run of the MTR3b_LCD, but it will not occur until 2022, if at all.

MTR-SSB development:  (12/6/19): We regret to inform that the new MTR-SSB transceiver will not be released as planned. In most simplest terms, there are some technical limitations preventing operations when extending it to the 40M/20M bands. The 80M/60M bands for the emergency communications interest is not affected. The minimalistic nature and outstanding reliability in all of the Steve Weber KD1JV Mountain Topper designs are well documented and will not be compromised which I’m sure everyone appreciates. So while we are all disappointed, we are gauging interest in the 80M/60M version in 2020 and are considering special single band versions as well.

EndFedZ Antennas (Acquisition): LNR is pleased to announce that the PAR EndfedZ line of wire antennas was acquired by Vibroplex in 2019. Customers can purchase these antennas directly at their website at This move is a positive for both companies and we are excited about the future going forward. 

W4OP Loop: Unfortunately, as part of our streamlining in 2019, we halted production of the W4OP Loop antennas to devote our entire attention on the very popular Mountain Topper transceiver line. The W4OP (remote and manual controlled versions) are phenomenal antennas and would be a great product line for another company or interested entrepreneur to pick up. If interested, contact LNR.

New Mountain Topper Facebook Group PageMountain Topper Facebook Group Page – Cool customer driven FB page to share stories, pics and general MTR discussion.


Running mtr3b lcd 2.5 watts 15,000+ kilometer contacts – Bushcraft Ham Radio

MTR3b LCD with a view!

I thought you might enjoy the attached two photos of an activation I did today with the new  3BLCD MTR. This was near  Makapu’u lighthouse on Oahu today.  Antenna  was the Endfed  10/20/40. 


Love the Clock feature

“The new MTR3b with the LCD display is a major upgrade for the Mountain Topper. The display provides frequency readout, clock with battery backup, keyer speed and battery voltage while reducing the very low current draw from 35 mA to only 15 mA. The new LCD frequency readout makes the new Mountain Topper much easier to tune. The Mountain Topper is a great “purist” radio for SOTA and other outdoor activities.” -W3DX


Receive is Amazing!

This little is amazing. It’s so fun to use. The receive is amazing.


Perfect Sota Rig

I’ve owned and operated alot of the MTR-series from the original Weber kits to this latest one from LNR …I got to say this one with it’s large LCD display makes it look and feel like a big bench rig yet small enough to fit in your pocket! Perfect SOTA CW rig! 


Easy to Read

I received my MTR-3B today and love it. I was afraid that the display might
as difficult to read as the one on my MTR-5B but it is not the case, it is
very bright and easy to read. Having the 2 lines display is a huge improvement
over the single digit on my old MTR-3B.

Yvon NU6I


My MTR3B arrived today. What an amazing little radio. This will definitely go in my backpack next summer. With antenna, batteries, key and earphones, I believe I can have an HF station, in a padded, waterproof case, at under 3#. This rig redefines HF “portable”.


Mountain Topper TShirts, Hats and Other Accessories Now Available!

The Three Amigos - MTR5b, MTR3b, and MTR4b




"Mountain Topper Transceivers are Perfect for the Appalachian Trail"

MTR4b v2.3