Just this one time I went too far? ha-ha
George... I think you are overdoing it on this one....
Gil, I am always overdoing it.
bygones, but when dealing with micro volts, the crimp, lug bare no shield is a bummer from a loss stand point. When new its all good, but I have heard of many radio problems with old planes and this type of antenna. Each time problems where traced back to the antenna, corrosion and poor contacts. Its no big deal, just opinion and its not my plane.
RG-400 appears to be stranded as in the descriptions from the usual aircraft suppliers.
Not always some RG400 is solid core, some stranded. I'm not worried about solid core coaxial. It's plenty OK in coax with BNC connections. It's not a matter of fatigue or robustness,
stranded coax core is about flexibility. I laugh at using coaxial that cost $1.85/ft with an el-chepo antenna, when you can use $0.32/ft (or less) RG58 or the better LMR-195 equiv (about $0.45/ft). It seems ironic. Gil you make all good points, as usual, about good connections.
Again, yes... but the manufacturer has tested both and given them both an identical 3:1 SWR specification... which was the original point of my previous response...
The SWR is a function of vertical element not being straight up with a BENT WHIP, regardless of connection style. The BENT WHIP is not vertical so its not ideal, regardless of BNC or crimp wire wiring. The lower SWR's are for the ones that are not bent, but they have more drag. If I implied the connector was the reason for the SWR, thats not what I meant. SWR 3:1 is the spec for both, true. I can't get worried about SWR 3:1. SWR is a BASE 10 LOG function, so gain/loss between say SWR 2:1 v 3:1 is no big deal. Your points about good/bad connections are true. You can have a bad BNC connector for sure, which are hard to find. However over the years I just worry about the open wire connection of the "coat hanger" getting corroded.
We are talking micro volts, so just a little corrosion can cause some resistance and changes in antenna performance. The stainless whip (what kind of SS don't know) is OK but in direct contact with dissimilar metals its not ideal. The crimp terminal lug, copper wire, out in the air, touching SS will corrode, ever so slightly. The advantage of a sealed antenna base & BNC, besides fatigue, is less corrosion. The BNC is not going to last forever either, but with the open wiring moisture can get into it. Now add the electical voltage from transmitting, sitting there year after year, with no maintence or inspection, the connection might become poor over time. May be annual disassembly, inspection, cleaning or cap sealing the connection might help. It might take 10 years for corrosion to affect radio performance noticeably?
The BNC is isolated some what from the base. It's sits high and dry. Plus the BNC compatible plating is almost inert. It should be more maintence free. That's my story and I'm sticking to it. (We are truly splitting air molecules.)
No nothing in side, this is based on a plan from Jim Weir a long time ago. It does work great that's what others tell me-, no RF problems. But we should remember there is more to good transmitting than just the antenna
I have two commercial antennas. You can clearly see the sealed potting, silicon filling the base. Sealing might not be a bad idea (ref my corrosion rant and rave above). It does add weight. You antenna looks cool, nice work. (See thumb nail below, one is made Dorne and Margolin Inc., the other made my Decibel Products, Inc., you see the black or orange potting)
click
I didn't mean to cause such a ruckus....transmitting through my "coat hangar" antenna. As far as I'm concerned, it isn't broken, but could be improved maybe by shortening the leads, which I'll probably do when I get some time. Thank you all for your input. Mike
GEE I'm just kidding about the "coat hanger". I say "coat hanger" affectionately. It brings back memories of my childhood beatings. I'm KIDDING Mom & Dad, Love you. Lets call the "coat hanger" by the acronym: A-CRRED - Aerospace Communication Radiation Reception Element Device. Most antennas are just a wire or wires in some kind, shape or configuration. The devil is in the detail. Bad connections are bad connections whether a BNC or crimp lug. The basic physics of the "coat hanger", I mean A-CRRED is good, just the small detail of how you connect it is different. No offense meant. "Roger Roger, 10 by 10, over and out."