Hi Bob 1) Yes 2) When beaming NE you are feeding all elements with the NE element fed at 0 deg in phase, NW & SE both fed at -90 deg out of phase, and SW fed at -180 deg out of phase. 3) I don't see
You can also feed a 1/4 wave wire with the feed point grounded to one leg of a piece of 450 ohm window line and then short the bottom end of the window line at the appropriate length to make an eleva
Thanks Dave - you are correct these were 1/2 wave radiators not 1/4 wave. I did not describe the feed point details correctly either... memory here is not what it used to be For 10m I used 16.5 ft #1
Just want to reiterate that John and Jim both speak the truth. Years ago I used to cart an old GAP vertical dipole down to the Texas coastal islands every year for the IOTA contest. The difference in
It's typically not about the dead weight of the mast & antennas, it's about reducing the bending moment on the mast under wind loading. 73 Matt KM5VI Installing a thrust bearing in a tower - Dead wei
Thanks Scott and good point about the rotor reaction, but actually both statements are true because the bending moment at the base of a mast, without any intermediate horizontal support (thrust beari
Hi Grant & Very Merry Christmas. These are loads, not stresses. Stresses result from loads acting on member stiffness which produces strains and resulting deflections. 73 Matt KM5VI How does that wor
Hi Scott & you are spot on. My original post was trying to point out exactly what you are conveying, that thrust bearings in tower applications are employed to better deal with horizontal loadings mo
Didn't ON4UN give a presentation at Dayton in 2005 that covered his testing of different 4-square feed systems? I thought his conclusion was that there was less than a 1dB difference in performance f
As an alternative suggestion.... I have been using flange mounted pillow block bearings as mast thrust bearings - first time was about 20 years ago. IMHO they are typically plenty strong - ratings ar
Try this site... much more accurate & detailed data than the old 1954 map. https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx For your area near Crockett, also might want to look at on TAM
Hi Rick, Hope all is well. Zoom in the map to display your area. Use the AOI menu tool to define an area of interest. Click on the Soil Data Explorer tab Click on the Soil Reports tab At the left, fi
Crank-up tower lift cable pulley bearings... 73 Matt KM5VI What are these bearings used for on a tower? John KK9A I ordered some fom Ebay like Ray said. Got them for $30 each. Make sure they are KP8F
That would be a Hub City single reduction worm drive gear drive model series W300 in 40:1 gear ratio configuration A Older units will use axial and radial needle bearings on the main shaft and radial
I think ASTM F1554 replaced the previous anchor bolt standard since ~1994. F1554 standard tensile strength ratings are 36, 55, and 105 ksi. Matt KM5VI Yep, 1/2x12bb are the onesgrade 36 ? Sent from m
Thanks for the clarification Jim - you are correct. Those 105's you have must be pretty stout 73 Matt KM5VI <I think ASTM F1554 replaced the previous anchor bolt standard since ~1994. <F1554 standard
I found the following replacement seals fit my older Hub City box - these may or may not fit yours - check dimensions! TCM #06081 VM-BX (input shaft) TCM #20231 SM-H-BX (output shaft) Hope this helps
Hi Don, I have a fabrication shop drawing for a Triex W-51 dated January 1967. I don't have the installation manual. The shop drawing shows the two upper section legs are 1" x .065" tubing with 5/16"
Hi Bruce, Directional control for 240V motors generally requires a different configuration of switching functions than for 120V because the start windings need 120V to operate which is generally deri
Hi Paul, I believe there are two possibilities as to how rope would dampens element vibration. One is that it may add enough mass to lower the resonant frequency of the assembly to a value which is n