Ok so the last couple days in the afternoon My swr has spiked on me a few times, today it did not go down. Is this antenna shorted?
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Dumb ground plane question Help!
- Thread starter Enterprise312ok
- Start date
More info please....
- SWR spiked. To what? 3 or 4, or really really high?
- What kind of antenna is that? Looks like a tapped loading coil for matching which would explain the low DC resistance you are measuring.
- You have a VNA handy or just that scope?
- Is an amplifier involved or is this straight off that nice Washington?
- Was this while mobile or base on a windy day, or was the antenna sitting still when it happened???
- Do you have continuity between the middle lug inside the antenna base to where the whip connects? That solder joint looks suspicious...
- Was the radio golden screwdrivered in a way that might cause parasitic oscillations?
- When it would happen periodically, was it right away or after the radio warmed up? And what did you do to remedy the issue/how did the problem go away the first few times?
- SWR spiked. To what? 3 or 4, or really really high?
- What kind of antenna is that? Looks like a tapped loading coil for matching which would explain the low DC resistance you are measuring.
- You have a VNA handy or just that scope?
- Is an amplifier involved or is this straight off that nice Washington?
- Was this while mobile or base on a windy day, or was the antenna sitting still when it happened???
- Do you have continuity between the middle lug inside the antenna base to where the whip connects? That solder joint looks suspicious...
- Was the radio golden screwdrivered in a way that might cause parasitic oscillations?
- When it would happen periodically, was it right away or after the radio warmed up? And what did you do to remedy the issue/how did the problem go away the first few times?
The antenna is a sirio venom 5/8. At the time I was running mr lincoln2 + through my rm italy 203p (75 watt) noticed the swr spike on my mfj versa tuner v's cross needdle meter and 5 to 10 swr on the lincolns swr display. thought it may be a short, so I tested my cax it with my multi meter and saw the low resistance. was not windy
DC and RF are totally different things. Dead shorts to DC can look like open circuits to RF. I made a video and shared it here a while back, and in it you can see why.
the ugly solder joints were added by me after trying to get my swr below 2.0, I had a flat 2.0 match across the regular 40 and that is why a got the mfj tuner to protect my sweep tube box and also expand my tuning range to use with my lincoln 2 plus
Tubes? Something might be causing the amp to break into oscillation. Remove the amp and test SWR with a barefoot radio or different amp before continuing the brutal assault on that antenna
jk
was not running tubed, swr was tested with barefoot radio as soon as i saw it spike and after waiti g about 20 min, just glad to know. the dc short doesent mean game over. If i hurry I can get antenna up and mounted for more testing before its too dark
Well the sirio survived the brutal assult. Back to normal swr, the swr spikes around 4-6 pm must be some kind of thermal issue maybe with the silicone over the joints in the antenna
A long shot here, but have you had any hard rain lately? And did you check your coax? If you have the type with the foam insulation and it's not sealed right or has holes or cracks, it can wick water like a sponge and cause up/down SWR.
Thus the reason you get GOOD coax and solder and SEAL your PL-259's properly. Don't even bother with the cheap stuff! You'll only regret it later!
Thus the reason you get GOOD coax and solder and SEAL your PL-259's properly. Don't even bother with the cheap stuff! You'll only regret it later!
