EFHW- End Fed Half Wave transformers

Ever since March 2015 when we started to market the High Ratio/Wideband transformers for EFHW antennas the work on R&D (Research & Development) never stopped. The number of limitations in the design of 49-81:1 ratio of impedance transformation over large HF frequency spectrum (1-30MHz) was challenging and final designs are always some sort of compromise. The market demands and drives the constant improvement of power handling, lower insertion loss, and better match to a single Half wave wire and its multiples. We reached some of the market demands and some of them are still limited by rules and mechanics of how these wideband/high ratio transformers operate.

Unlike some of the “copycats” and number of amateurs, who were trying to tap into the market by marketing inferior designs with huge losses and fake flat SWR plots based on increased losses, we are the only ones providing the real measurements of insertion losses of our transformers which are unmatched by anyone.

The losses in the range of 2-10% (~0.1-0.5dB) of our transformers compared to other various similar ones with losses of 15-35% (~0.7-2dB) makes a MyAntennas.com (Euroxpress Corporation) a worldwide leader in the design of very complex high power/ high ratio/wideband RF transformers.

Such transformers as our latest MEF-330-1K-Plus used in our new EFHW-8010-1K-Plus and EFHW-4010-1K-Plus antenna models feature an average loss of only -0.37dB from 3-30MHz, and our MEF-130-2K-Plus used in our EFHW-8010-2K-PLus, EFHW-7510-2K-Plus, and EFHW-4010-2K-Plus models, feature average loss of only -0.5dB from 1.8-30MHz. Our Low band transformers for 1.8-8Mhz such as MEF-105-5K, MEF-107-4K, and MEF-107-2K-Plus feature insertion losses of only 0.07-0.25dB. For increased power handling on digital modes such as FT8, we developed also a MEF-330-2K-Plus transformer for 3-30MHz with an average loss of only 0.47dB.

See some of our Insertion loss charts and explanation of the measurement

NEW products, EFHW-7510-2K, and 7510 wire assembly

We added a new product, An EFHW-7510-2K antenna which has low SWR at 75M (3.9MHz) while maintaining the same characteristics on bands above like 40,20,17M… etc, just like EFHW-8010 model does. For upgrades, we sell 7510 wire assembly in 14 AWG wire too for those who want to just switch the wires on their existing EFHW-8010 antennas. The links are here:

EFHW-7510-2K antenna

EFHW-7510 wire assembly

ZF9/ZF2XA Cayman Islands

It has been a year since I have visited Cayman Brac Island (ZF9) and operated as ZF9/ZF2XA in CQ WW WPX CW contest. The antenna was EFHW-4010 set as inverted, actually lazy L right at the beachfront taking advantage of salt water and partial vertical polarization of an antenna. The 2000 contacts were made with ICOM 7300 and 100W over the weekend during this small DXpedition, 73 Danny, E73M aka N4EXA & ZF2XA

Summer Break 2018, June 28th – August 4th

Summer Break at MyAntennas.com

As we did last year this summer break will last from June 28 – August 4th when we will resume shipping the products sold during the break in order as they were received.

Some design and experimental work will be done during that time at our Contest location-E73M in Bosnia.

I am looking forward to hearing you on the bands, especially those using our EFHW antennas.

 73 Danny N4EXA/E73M

 

2017, another record year at MyAntennas.com

As expected 2017 was another record year at Myantennas.com with thousands of products shipped to 106 DXCC countries all over the world. Our products are becoming very popular among HAMs with great positive reviews resulting in growing demand for EFHW antennas and CMC’s as our bestsellers.

This morning on January 2nd, 2018 we were surprised with another cold day in Florida with temperatures plunging down to 5 deg. Celsius forcing our “Santa” mailman to wear the cap and fleece while picking up the “presents” accumulated over the new years weekend.

I wish you all Happy New Year

Danny Horvat, E73M, President Euroxpress corporation

MEF-107-2k+NEW High Power EFHW transformer for 1-7MHz

The MEF-107-2k+ is new high power EFHW antenna transformer(~50:1 ratio) designed  with massive 1.25 pound (0.57kg) ferrite core, equivalent of almost six (6) 2.4-inch toroids and very low insertion loss for frequencies from 1-7MHz

Insertion loss measurement S21 with two back to back transformers shows only 0.18dB (4% power loss) at 160m and 0.28dB (6% power loss) on 40m bands.

Insertion loss for MEF-107-2k+

Field Day 2017

The FD 2017 is just around the corner.  During the Field Day, 2016 many used our popular EFHW-8010 and EFH-4010  models and reported excellent results. This year we added many products to our website including installation plates  (pole, tower etc.) for our EFHW-1K version as well as EFHW-HP version.  Recently we added a transformer  MEF-330-HP  (used in EFHW-8010-HP and 4010-HP models) as a separate item for those who want to build their custom EFHW  antennas  75m  or use at the MARS frequencies etc.

 

Good luck and enjoy this year field day event!

New! wire assemblies in #18 and #14 sizes

We listen!

Some of you expressed the need for thicker 14ga wire more suitable for harsh environments with snow and sleet. We added also our standard 18ga wires for those who often tie the wire to moving trees and forgot to leave some slack. Anyway, they are all available at our “Accessories” section, see the link below.

https://myantennas.com/wpproduct-category/accessories/wire/

Shipping DXCC award, almost!

It has been just little over two years since  MyAntennas.com started its production operation in Florida.  Being avid contester and DX-er I wondered how many countries (DXCC) we ship our products to in these two years. Well, with the recent addition of Barbados (8P) we placed a pin #97 at our DXCC world map. See the image bellow. 

 

73 Danny N4EXA aka E73M

NEW CMC-130S-3K

The new CMC-130S-3K  is an economy version of already popular CMC-130-3K  with 0ver 5000-10000 Ohms of CMI (Common Mode Impedance) or ~40dB attenuation in 50Ohms systems on all HAM bands 160-10m

Priced at $59.95 it greatly outmatch any similar size product on the market.

 

NEW! 2kW ICAS Broadband transformers and EFHW antennas

After few beta testers, we started building and selling two new transformers capable of 2kW ICAS.

The new transformers MEF-330-2K (3-30MHZ) and MEF-310-2K (3-10Mhz) are the product of the constant search for best designs in order to satisfy the need of some users wanting a reliable EFHW antennas capable of withstanding the longer periods of transmission with high power without overheating the transformer which results in a change of Ferrite material.

It is known that every RF broadband transformer has insertion loss which converts to heat into ferrite core which after reaching its curie temperature (not saturation) changes the properties of transformation ratio and results in elevation of SWR of the antenna.

These two new transformers use ferrite material with higher curie temperature and larger cores in order to dissipate the heat easier than smaller transformer like MEF-330-1K (1kW ICAS version).

Results are great, MEF-310-2K has an only 0.14dB loss on 80 and 40m  while MEF-330-2K average the loss of 0.55-0.6dB from 3-30Mhz.

New antenna model, EFHW-8010-2K is already in production and will satisfy many users wanting to use them in CW/Phone “rag chewing” style of operation as well as DXpedition and contest style of operation.

The new duo-band model EFHW-7540-2K will come out soon with unique feature covering the 75m (3.8MHz)  and 40m (7-7.3MHz) bands without use of traps and only 110ft long. It will satisfy many users wanting to have single wire antenna capable of legal power on phone part (75m) as well as the whole 40m band with low SWR.

Stay tuned and Happy Holidays,

Danny Horvat N4EXA aka E73M

EFHW 1500W capable transformer MEF-330-HP

It has been a long search for suitable materials and quite a few experimenting has been done to design a high ratio (~50:1) transformer for EFHW antennas capable of high power (1500W ICAS). In the same time,  it was hard to cover the wide range of HF spectrum from  3-30Mhz, yet I did it again!

I am proud to announce that new transformer MEF-330-HP is almost double in size of  its little brother  MEF-330-1K and also has a bit less insertion loss on all frequencies between 3 and 30MHz. A new transformer will be incorporated into new/old  EFHW antenna models EFHW-8010-HP and EFHW-4010-HP as well it will be sold separately for those who want to make their antennas for use out of HAM frequencies for their needs such as MARS, Marine or EMCOM activities.

New models can be seen at these links EFHW-8010-HP and EFHW-4010-HP

Also, see this short video of testing the antenna with a new transformer at 1500W.

73 Danny Horvat, N4EXA aka E73M

 

New line of single band Dipoles MY-DP-160-10M

MyAntennas.com is launching a new line of single band Dipole antennas for all Bands from 160-10m.

Dipoles are featuring:

  •  high-quality PBT material housing for 1:1 BALUN wound with PTFE coaxial cable capable of at least 3kW ICAS on all bands.
  • Stranded #14 AWG black tinned wire with simplex wire clams and black high impact insulators.

Removable Simplex clamp on ends allows for easier adjustment of dipoles resonant length  Models can be seen on the link here https://myantennas.com/wpproduct/my-dp160-10m/

dipole-160-10m-9  dipole-160-10m-8

CMC- Common Mode Choke as noise reducer video by AC0HF

I have been writing about great results I and many others had with the use of CMC- Common Mode Chokes as noise reducers when inserted in your coaxial lines. Many CMC’s  have been sold by MyAntennas.com and many positive reports came from happy customers. Please see the great video report  by AC0HF who demonstrated reduction of noise averaging a 3S-units (18dB).

We have received reports from few with results of 5 S-units  (30dB) and more of reduction of noise.

73 Danny N4EXA aka E73M