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Hot Rodz™ Patented For Use With Mobile or Base Screwdriver Antennas  Hot Rodz kits include:
Installing DX Engineering Hot Rodz on Your Screwdriver Antenna.  Read the Safety Tips on page 4 1. Remove the long whip from the top of the screwdriver antenna. 2. If you are not using a stinger, place the fiber washer on the 1/2 inch bolt and install in the top of the hub 3. Install the hub on the mast and tighten the locking nut. 4. Place a smaller plastic cap over the end of each stainless rod that you are using. 5. Push the stainless rods into the hub in the configuration chosen. 6. Install the mast and Hot Rodz assembly to the antenna or to the spring (optional). Tighten locking nut. 7. Adjust rods and/or stinger for the lowest SWR at the desired frequency. 8. After adjusting the stainless rods for the desired frequency, place plastic caps on any remaining exposed ends. TECH NOTES DX Engineering Hot Rodz™ DX Engineering Hot Rodz is an adjustable capacity hat system that reduces the amount of RF energy lost through the coil so greater energy is radiated by the antenna. Lower coil loss also increases received signal strength. The DX Engineering Hot Rodz system increases the efficiency and gain of screwdriver antennas. Some Basics A word about matching The base impedance of the antenna drops to about 16-22 ohms when you increase the efficiency of the antenna with the DX Engineering Hot Rodz. In most cases, matching problems are solved with the use of an antenna matcher such as the DX Engineering MM-1 Auto/Transformer. How much did the efficiency increase? If the base impedance was reduced from 50-ohms total to 20-ohms total when the actual radiation resistance of the antenna is 3 ohms, then you will have more than doubled the RF power coming out of your antenna by raising its efficiency from 6% to 15%. Let's look at an example of the use of DX Engineering Hot Rodz™ The Tarheel model 200A screwdriver antenna covers 10 - 80 meter bands (3.1 – 28.5 MHz) utilizing a 6 foot whip. The 6 foot whip section can be replaced with a DX Engineering Hot Rodz system with three 12 inch rods, the standard 22 inch mast, and safety spring. At 3.5 MHz the total length of the antenna with a Hot Rodz assembly is 6 feet 11 inches total compared to the 12 foot length for a standard Taheel. This will make a big difference in where your vehicle will fit without having to stop to shorten the antenna. Using just three of the 24 inch stainless rods that come with the kit, your screwdriver can cover a huge part of the HF spectrum, but we supply six rods (18 total) of each of the following lengths: 6,12, and 24 inch. Using more of the rods (or longer ones) is like extending the whip on a regular antenna! But the more DX Engineering Hot Rodz you use the more your antenna efficiency will go up. Here's why: The Tarheel and other screwdriver antennas are excellent examples of the art of engineering for the mobile environment. But due to design considerations common to all screwdrivers, the Q (a measure of efficiency) of the coil is low--(only about 75-100). Just as you would expect, the less coil that is used the better. DX Engineering Hot Rodz allow you to use less coil for any given frequency. This increases the amount of power that your antenna radiates, increasing the feedpoint impedance. That translates to stronger signals when transmitting or receiving. Unlike fixed capacitance hats sold by others, the complete adjustability of DX Engineering Hot Rodz™ allows you to balance the frequency range of the screwdriver antenna with the efficiency that you need on your favorite frequencies. Adjusting Hot Rodz To An Exact Frequency Hot Rodz can be adjusted for the exact frequency that you need. To lower the frequency of your Hot Rodz equipped antenna, do one or more of the following:
SAFETY TIPS
DX Engineering Hot Rodz and Your Screwdriver Antenna as a Base Antenna Our fully-adjustable DX Engineering Hot Rodz will work for a base system antenna just as well as a mobile antenna. DX Engineering Hot Rodz will allow you to use your antenna on a lower frequency band then you might be otherwise able to do, and will allow a lower profile antenna with increased efficiency so more of your RF power goes to your contact and less to heat the worms. Of course, a shorter antenna will attract less attention, so replacing that 6 foot whip on top of the screwdriver with our 24 inch high capacity hat system is going to go a long way toward keeping your antenna stealthy. Most screwdrivers are sold with a mounting bracket that can be attached between the main unit and a mounting tube of any diameter up to about 1.25 inch. Drive a 1.25 OD pipe into the ground to a depth of about 4 feet and leave about 2 feet out of the ground. The 1.25 inch OD would probably be about a 1 inch water pipe size. You can use a cap on the pipe to keep it from being deformed while you drive it into the ground. You can remove it afterwards. Next, slip the DX Engineering Stainless Steel Radial Plate (DXE-RADP-1P) over the pipe and attach the radial plate to the pipe at ground level with the U-bolt saddle clamp (DXE-SAD-175A). Then attach the radials. The Radial Plate comes with enough hardware to attach 20 radials. Additional radial plate hardware kits can be purchased to attach a total of 60 radials to the plate. Visit DXEngineering.com for directions on How to install disappearing radial wires without digging. Next, attach the antenna to the pipe using the mounting bracket from the screwdriver manufacturer. Last, attach the coax to the Radial Plate by using a Bulkhead Fitting (DXE-363-SST). Then run a short section of coax to the bottom of the antenna feedpoint from the Radial Plate. Additional size rods are available, including 48 inch and 72 inch long ones that will get you down to the 160-meter band. Tech Help available at: 330.572.3200 M-F 8:30AM - 4:30PM EST Or dxengineering@dxengineering.com |
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