50:450 ohm (9:1) CUBE™ Balun, 1.8-31 MHz, 5 KW, ladder line, ZEPP, T2FDProduct DetailsMPN: CB-9-5000Input ohms/Output ohms: 50 in / 450 outputFrequency Range < 2:1 SWR (MHz): 1-31PEP Power Rating (watts): 5000Model CB-9-5000 is a 9:1 multi-core, balanced output balun housed in a NEMA enclosure box (4″ x 4″ x 2″) with top studs (TS) used to translate a 50 ohm input up to 450 ohms at RF power levels up to 5000 watts PEP when used with a matched load. With matched 450 ohm load the SWR over the frequency range 1 to 31 MHz is less than 2:1 on the coax feed side.
All power rating are PEP, 100%, continuous digital modes are 30% duty factor rating of PEP, FT-8 digital mode rated at 1500 watts.
Application note: If using 450 ohm ladder line on the output of the balun top studs, make sure the impedance seen at the balun end of the ladder line is near 450 ohms since the ladder line acts as an impedance transformer, the impedance at the end of the ladder line may be different than the characteristic 450 ohms of the ladder line. For example a 1/4 wavelength of ladder line will transform a high impedance at the antenna feed point to a very low impedance at the other end connected to the balun thus placing a very low impedance load on a balun expecting 450 ohms and such a load may damage the balun. The impedance seen at the balun output should be near 450 ohms for full power rating.
Model CB-9-5000 is a 9:1 multi-core, balanced output balun housed in a NEMA enclosure box (4″ x 4″ x 2″) with top studs (TS) used to translate a 50 ohm input up to 450 ohms at RF power levels up to 5000 watts PEP when used with a matched load. With matched 450 ohm load the SWR over the frequency range 1 to 31 MHz is less than 2:1 on the coax feed side.
All power rating are PEP, 100%, continuous digital modes are 30% duty factor rating of PEP, FT-8 digital mode rated at 1500 watts.
Application note: If using 450 ohm ladder line on the output of the balun top studs, make sure the impedance seen at the balun end of the ladder line is near 450 ohms since the ladder line acts as an impedance transformer, the impedance at the end of the ladder line may be different than the characteristic 450 ohms of the ladder line. For example a 1/4 wavelength of ladder line will transform a high impedance at the antenna feed point to a very low impedance at the other end connected to the balun thus placing a very low impedance load on a balun expecting 450 ohms and such a load may damage the balun. The impedance seen at the balun output should be near 450 ohms for full power rating.
TECH NOTE: We also stock RFI kits to protect effected devices such as garage door openers, computers (laptops, desktops), dsl/cable routers, ethernet hubs and many more devices. If you run a high powered RF amplifier in your ham station also consider a linear amp RFI kit which will cut down RFI transmitted by your station. Remember there is always a “transmitter” and a “receiver” of RFI and the quest is to find and choke the “path” the RFI has selected – you need to add ferrites to both the transmitting side and the receiving side to eliminate RFI problems. The RFI-HTS kit only helps suppress RFI on the receiving side.
Typical RFI Problem/Solution:
Hello, I am Larry, a ham operator and I am having interference issues with my Direct TV system. My station is a FT450D through an Ameritron ALS-600. From the amp through a coax switch to choose between an OCF dipole or an Hustler 5BTV vertical. Any power over 100 watts and my DTV goes off the air and must completly reboot/format. Coax is RG-8. The DTV dish is pointed away from the dipole and separated by about 25'. DTV was totally useless! They suggested I not talk on the radio while she is watching TV! Please help me with a reasonable, cost effective soultion. (The wife gets really pissed when I shutdown the tv!) Thank you, Larry
Hi Larry,
Your RFI problem is quite common and is usually a sign of either a radiating coax feed line or reception of your radiated signal (source) by the Direct TV (the victim) through either the AC power lines acting as “antennas” for your ham signal or the coax braid of the satellite antenna acting as an antenna for your signal.
The solutions are straight forward:
1. To make sure your feed line is not radiating you need a feed line choke at each antenna feed point (also makes your antenna work better since it is not using the coax as part of the antenna). You can use our simple Kit 110 with 5 snap on chokes on each antenna for this purpose. Part # Kit 110 at $27.50 each – one for each antenna. These chokes will keep your feed line from radiating and coupling into your ac power lines. INFO HERE
2. The radiation from your antennas themselves may also be getting into the ac power lines and coax braid of the Direct TV antenna so you need to protect the victim receiver. Depending upon the sophistication of your direct TV setup (e.g. home theater, dvd, tape player, sub woofer speakers, etc), the path of the RFI may be coming thru the AC power lines of any connected device to the video including the video monitor itself! To help solve this problem we have a home theater RFI kit for up to 5 devices (you need a minimum of two – one for the Direct TV receiver(AC and coax input) and another for the video monitor AC power lines and HDMI or video input cable. Our kit part # is RFI-HTS. INFO HERE
These items should help reduce the RFI and let you operate on the air while your wife watches TV.
Bob Brehm, AK6R
Chief Engineer