Description
MEF-330-1K-Plus Multi-Band End Fed Half Wave Antenna Transformer 56:1 Ratio
Features three 2.4 inch ferrite cores and very low average Insertion loss ~0.37dB
This is an End-Fed Half-Wave antenna (EFHW) transformer covering 80/10m amateur bands or any frequency in between. It transforms high impedance ~2800 Ohms at the end of the half-wave radiator to 50 Ohms and features very low insertion loss. Average insertion loss from 3.5-30 MHz is ~ 0.37 dB
- NO TUNER needed!
- NO counterpoise needed!
- Grounding of cable at the entrance to the home is recommended
- Frequency coverage: 3.5-30MHz
- Power Handling: 1kW I.C.A.S
- 250W continuous in digital modes such as FT8 etc.
- Polycarbonate housing
- Hardware: Stainless Steel
- Connector: Silver/PTFE (Teflon) SO-239
The wire length can be calculated by the following formulas:
- Length (feet)= 468/Frequency (MHz) or
- Length (meters)=142.5/Frequency (MHz)
Always cut a wire a bit longer to allow for tuning to your desired frequency. Tuning depends on the height above ground and nearby objects. There are so many ways to install the wire and your imagination is the only limit. You can do it horizontal, vertical, sloping, an inverted “L” shape, Horizontal “L”, in “inverted “V” shape, etc.
Such an antenna will not need radials and in most cases NO Tuner at all. Be a radio amateur and do some experiments.
Grounding at the lug next to the SO239 connector is recommended! Long wires tend to collect electrostatic charges (usually when the weather is stormy) which can produce ESD (electrostatic discharge) at the end of your cable and damage your equipment.
The longer wire will give you more harmonic-related resonances, For example, Half Wave wire for 80m or 3.5MHz will give you (8) eight resonances up to 30MHz. VSWR curve might be a bit different at your location. Always aim to put the wire higher and leave the wire a bit longer at the end in order to tune it at the desired frequency. The EFHW instruction manual is available on the FAQ.
Dom, F4BWJ –
I’ve installed the MEF-330-1K with around 132ft of stainless 3mm diameter wire.
The MEF-330-1K is installed at 1,10m from the ground the wire goes quite vertically to 5/6m high and the rest of the wire goes to 12/13m high on the top of a tree.
First of all what is noticeable is the noise floor level which is lower than I got with other antennas such as G5RV, long Wire, dipole, Conrad Windom etc…
With the EFHW antenna the noise level is around 53 to 55 on 80m during the day as I get 57 to 59 with other antennas.
Also the received signals can be very strong in despite of low noise floor level (higher than a long wire or G5RV for example).
From South West part of France, my first contacts with this antenna on 80m have been made with only 100W from my SDR MB-1 early in the morning with north American stations between 6:00am and 7:00am UTC (NY2PO -5843kms, KK6ZM/1 -5386kms, W1/DL4NAC – 5562kms…), New Zeeland station (ZL1AIX – 19187kms) and just this morning 11/03/2016 at 6:45 UTC Cayman Island (ZF2ZB in a tremendous pile up with big guns stations all over Europe!!! – 7771kms)..
I’ve made some tests on 17m and 12m WARC Bands with success too (e.g. first contact on 12m band with CX7SS).
The sole problem I encounter is with 30m band, SWR is around 2,7/3.0 and in despite the ATU transceiver is normally able to tune antennas with such SWR, it’ cannot match my EFHW antenna. This is not very important for me as I don’t use this band.
In conclusion, very interesting beginnings for this homemade EFHW 132 ft. antenna fed with the MEF-330-1K transformer!!!
NB: I apologize for my broken english in this review as I’m a French ham.
Dom, F4BWJ.
Marcius E. Chester –
Danny all I can say is “WOW” this
MEF-330-1K Transformer attached to a 66′ 18g wire in a sloper/slanted L configuration up 35′ in a 40′ tree is the best antenna I have ever had. Due to living in a HOA development I’m not able to put a antenna on the roof. This transformer works perfect on 11 meters. Swr: 1.0: 26.965- 1.0: 27.405. Keep up the good work and think about building 64:1 transformers.
73
Rev. Doctor MC. Big Mac-233
Southern California