I like the idea of the 1/2 w/l radiator, as against the usual 1/4 w/l fed against ground. My 'homebrew' version works extremely well, and I use it as my 'standby' and 'reference' antenna.
I like the idea of the 1/2 w/l radiator, as against the usual 1/4 w/l fed against ground. My 'homebrew' version works extremely well, and I use it as my 'standby' and 'reference' antenna.
(Circuit diagram of the matchbox)
There are a few problems which arise from time to time in older units. especially in wet and windy areas. or close to the Sea.
Varying, or high SWR on one or two bands.
This isusually caused by bad connections on the trap clamping arms. They should be carefully loosened, moved aside, and the contact area cleaned with steel wool. When clean, the area should be greased with Vaseline, or one of those dissimilar metal contact greases used by the electrical power utilities.
If this treatment doesn't work, and you still have high SWR one band, Then you have a ..
Hl-5150d driver windows 10. Faulty trap.
Traps usually go faulty because the heatshrink seal on the trap fails, and water gets inside the coaxial 'trombone' capacitors on the traps. If the insideof the tube gets wet, this changes the dielectric constant of the capacitor, and the value of the capacitor changes, thus moving the resonant frequency of the trap. You will find that the SWR minimum point has moved, and normal adjustment will not bring it back on frequency.
If this situation is not corrected, eventually the capacitor will short out, especially if you're running high power.
Running high power into a bad SWR can eventually destroy the matching unit.!!!! More on that later..
To Cave story english download. repair the trap, you must carefully note the length that the capacitor 'rod' extends out of the 'Tube'. The rod can slide in and out of the tube, and is one plate of the capacitor, so you need to get it back the way it was before you dismantled it..!
Carefully dismantle this capacitor. Dry and clean all of the components, and reassemble. Re-seal the tube with 'self-amalgamating' tape.
All should now be well again..
If the insulator tubing is badly damaged, you should go to Gerry VE6LB's page. He has a great method of repairing traps using Hot Melt Glue. When you see the original damaged trap, you'll be amazed that it could ever be fixed. Well done Gerry!
If you have high SWR on ALL bands, then you probably have a
Faulty Matching Unit.
A - Matching capacitors. These are a pair of 86pF in series, to give an actual value of 40/50pF. These can, and do go open-circuit. Replace them with a single HIGH CURRENTtype (doorknob) of 50pF if you can. ( I use three 15pF caps in parallel)
B - 4:1 BALUN transformer. These can actually disintegrate with bad SWR and high power..Ouch !! Replace with an Amidon Iron Dust core T200-2 wound as in pic above.Or with a Q1 material Ferrite core ( FT240-61) wound with 6 bifiliar turns (as against 11 in the pic above).
C - This antenna, being asymetrically fed, needs an effective Choke Balun to keep RF from the exterior of your feedline.This should not give any trouble..But if it does, an Iron Dust Core will NOT work here. I use a ferrite core, Q1 material.
D - Make sure that all hardware connections are clean and secure
E - Moisture release vent.
F - Feed point (SO239)
G - PC board .
H - RF choke effectively DC grounds the radiator to help prevent static electricity from entering your shack.If everything else looks OK in the unit, and the SWR is high on ALL bands. Disconnect this choke. After heavy static, turns on the choke can become shorted. This damage may be impossible to see with the naked eye.
( Pic of my homebrew R7 matchbox. Not as pretty as the commercial one, but works just as well! )
Take a look at the brilliant rebuild job that Darren G0WCW did on a wrecked R5 Match box. It's now working perfectly again.
Any manuals that you may require for these antennae are available in .PDF format from the Cushcraft website .