HFp Frequently Asked Questions
Q - What is the maximum transmitter power that the HFp can handle?
A - The HFp can handle 200 Watts with no problem.
Q - How do you set up the HFp when it is pole-mounted or window-mounted?
A - The BackPack Mount and the Clamp (options) allow for setting up the HFp-V on a vertical support pole, extended out a window, or on a bench top or fence slat. In these setups, the element and radial configuration shown on the Laminated Card will most likely be incorrect. You will have to do some experimenting the get the antenna set correctly on your frequency. One of the portable SWR meters will make this task much easier.
Q - What is the max number of radials you have tested with this antenna and at what number do you find that the benefit and effort peak out?
A - We have tested the HFp with different numbers of radials and found that 3 seems to be the minimum number to be effective, and that more than 3 didn't seem to add much. Having the radials set to the correct "tuned" length was much more important. The "Radial" write-up explains this effect.
Q - Can the antenna be set up in an attic space? How would being inside affect performance?
A - The Vertical would probably not fit in most attics, but the Dipole might. As to performance, that would depend on how much metal (wiring, foil-backed insulation, roof flashing) was nearby. Metal in the near field of the antenna could de-tune the antenna from the tuning shown on the Laminated Card. But, the configurability of the HFp makes it likely that, with some effort, you could re-adjust the elements to get it resonant on your desired frequency. Again, one of the portable SWR meters will help simplify this task.
Q - What type of cable should I use between the antenna and the radio?
A - The answer to this question is "It depends!" Basically, you want to use the lowest loss cable that you can afford for the extended run of RF cable.
Some considerations - Smaller diameter cable has more loss than larger-diameter cable. But, the type of dielectric (the insulation between the center conductor and the shield) also is a major factor. And, any coax has more loss at higher frequencies than at lower ones, So, the determination is complicated. To help you understand the difference between different cables, HERE is an excellent coax cable loss calculator.
For reference, RG-8, RG-58, RG-214,, and RG-8X are some common, easily obtained cables to check. Other types may be more expensive and harder to find.
Q - What length of cable should I use between the antenna and the radio?
A - To avoid de-tuning the antenna, you should be at least a quarter-wave away from the antenna at the frequency you are using, and farther is better. And - be sure to read the next question.
Q - What are the RF exposure considerations for the HFp?
A - OSHA and the FCC have published guidelines for RF exposure, and the ARRL has a comprehensive write-up on the subject available, although the "official" information can be difficult to comprehend. We have tried to make the subject a bit more understandable here. This is required reading for the folks who want to do HF "pedestrian portable" operation, and recommended for everyone using radio transmitters.
Q - How long does it take to put up or take down an HFp, or to change bands?
A - Because the HFp design is a bit different from most HF antennas, the first time you set it up, you will take a bit longer while you get used to the concept. But, after you've done it a couple of times, you will find that set-up will take about five minutes. Take-down, or band-change takes just a couple of minutes.
Q - Do I need a tuner with the HFp?
A - In most situations, because of its highly configurable design, the HFp can be adjusted to match the feedline on the target frequency. Thus, a tuner is not necessary.
Remember that a "tuner" only masks the fact that an antenna is not matched to the feedline, so that the radio will be happy - it has nothing to do with the actual tuning of the antenna. Thus, if you have to use a "tuner", it means that the antenna is not set up properly.
Q - Will the HFp work on multiple bands?
A - The HFp is basically a one-band-at-a-time antenna. Changing bands requires that the elements be re-configured - with one exception. It is possible to set up the HFp on 40 Meters (7 MHz), and use the same configuration on 15 Meters (21 MHz), because of the 3-1 frequency relationship between the bands. This could also work with 30 Meters (10 MHz) and 10 Meters (30 MHz).
You could also use the HFp with a "tuner" to operate on bands other than the set-up band, but it would essentially be just a random length of wire on the non-resonant bands.
