5:1 CUBE™ Unun – Model CU-5-1500 (50:250 Ohm, 1.8-61 MHz, 1.5KW PEP)
Application. For traveling wave, end fed or portable 20-31 foot vertical antennas the 5:1 unun makes a good transformer for converting 50 ohm coax to a 250 ohm feed point. If you use the antenna on multiple bands, the feed point impedance may not always be 250 ohms and use of the unun at high (>350 ohms) or low (<100 ohms) will require reduced power input or the unun may have its power ratings exceeded and damage to the unun may occur. The (5:1 conversion ratio will change for loads other than 250 ohms unbalanced.
Typical application:
Also available as a balanced output – CB-5-1500
End Fed Feed Line Choke for Non-Resonant and End Fed Half Wave AntennasProduct DetailsType: 8-10 turns of RG-8X with Pl259 Connector, 3 turns of RG-213 cableRFI Range (MHz): 1-300 MHzID-B (in/mm): 1.4"OD-A (in/mm): 2.4"Height-C (in/mm): 1/2"Feed Line Choke
Each end fed antenna needs a feed line
choke at the radio end of the coax to stop the antenna common mode
current (on the coax braid) from getting into the radio when
transmitting and also to stop RFI common mode noise when receiving. The
simplest, most cost effective choke is a ferrite ring (F240 size)
installed as shown in the picture (at the transceiver end of the coax)
Add the Feed line choke (part # EFFLC-240) for $10 to your end fed
today and stop the pesky RFI from getting into your radio and causing
audio distortion or unexpected operation!
NOTE: Coax shown in picture is NOT INCLUDED and is shown as an installation example only. If you want a pre-wound choke check part# JC-1-1500-3 or JC-1-1500-6.
For non-resonant end fed antennas placement of the choke from 16-95 feet away from the antenna feed point to use the coax braid as the counterpoise (since these antennas are really off center fed dipoles with the short side using the coax braid as the counterpoise. Wind 8-10 turns thru center for an effective 3-30 MHz choke. See Bullet Antenna configurations for exact choke placement depending upon wire length.
For End fed Half Wave antennas place 1-3 feet from antenna feed point to act as short counterpoise for these voltage fed antennas. Use 8-10 turns.
On Sale
RG-8X Coax Jumper Cable with PL-259's on each end - 3 feetRG-8X Coax Jumper Cable with PL-259's on each end - 3 feetSKU RG-8X-3List price $19.95 Save 15%$16.95
Feed Line Choke
Each end fed antenna needs a feed line
choke at the radio end of the coax to stop the antenna common mode
current (on the coax braid) from getting into the radio when
transmitting and also to stop RFI common mode noise when receiving. The
simplest, most cost effective choke is a ferrite ring (F240 size)
installed as shown in the picture (at the transceiver end of the coax)
Add the Feed line choke (part # EFFLC-240) for $10 to your end fed
today and stop the pesky RFI from getting into your radio and causing
audio distortion or unexpected operation!
NOTE: Coax shown in picture is NOT INCLUDED and is shown as an installation example only. If you want a pre-wound choke check part# JC-1-1500-3 or JC-1-1500-6.
For non-resonant end fed antennas placement of the choke from 16-95 feet away from the antenna feed point to use the coax braid as the counterpoise (since these antennas are really off center fed dipoles with the short side using the coax braid as the counterpoise. Wind 8-10 turns thru center for an effective 3-30 MHz choke. See Bullet Antenna configurations for exact choke placement depending upon wire length.
For End fed Half Wave antennas place 1-3 feet from antenna feed point to act as short counterpoise for these voltage fed antennas. Use 8-10 turns.