LMR-400, and, if I had to guess, approximately 175 feet.
If we could go directly through the roof (which we can’t) above the Electronics lab, then I wouldn’t be so concerned about coax loss, but we’ve got to find the nearest existing penetration and use that. Given that the rebar is likely not grounded and will re-radiate our signal (perhaps in odd directions), I feel it is an acceptable stop-gap solution. We’re looking to get into local repeaters, not do DX with it.
DX may not be the goal, but good signal to Dallas, Denton, Mesquite, and Ft Worth would all be good things in bad weather.
I very much doubt the rebar will re-radiate in any useful way. ( I could be mistaken, but 35 years of ham radio suggests the attic is not optimum. ) If we are stuck with the attic, go as high as possible at least. That’ll help.
146 MHz loss is 2.6dB and 450 MHz loss is 4.7 dB through 175 feet of LMR-400. Not great, but the height would make up for some of it.
I haven’t seen it yet, but is there maybe enough sheet metal around the fume hood penetration that we could install an N connector feedthru ? That would shorten the path quite a bit I think.
The fume hood doesn’t penetrate, it’s a filter-based system.
The one for the plasma cutter ? I think not.
That’s a vent, not a fume hood.
There’s an actual fume hood over in Science, that’s what I thought you were talking about.
Nope. Roof penetration is a necessary part of the proposed plan.
The most successful path that I’ve seen was to use the control wire penetration near an roof-top HVAC unit. That’s what the weather-station people did.
The closest unit would be the one over the woodshop, I believe.
Sounds worth a look.
Not sure how much room there is in those. If it’s limited, we could go to the LMR version of RG-58 for a few feet to get outside. That wouldn’t kill us loss wise if we use good connectors.
Be nice if we could find a reliable ground where we go thru the roof and add a polyphaser.
A piece of network cable run with whatever coax used would get us an ARDEN or Broadband Hamnet node too. That could be made isolated enough to not worry about non-licensed folks I think. Power injector locked inside a box so the connection is not easy to get to would likely be enough.
I would probably stay at least a half wavelength below the roof trusses. But that still gains considerable elevation above in the room.
Update on ham radio desk in Electronics:
Andy KE5KOF and I worked on it today. We were assisted by Ben KG5ISF who happened to be in the lab working on a project and jumped in to help with the panel project.
Accomplished:
Completed the Power Pole installation
Reversed the awesome panel meter so that it reads right-side-up.
Drilled and mounted the LED indicator for the roof-top antenna tuner
Replaced the 20A main auto-reset circuit breaker with a 30A breaker
Installed the 32A (peak) Alinco power supply. This supply has a cigarette/accessory socket and two sets of spring clip wire connectors on the front panel, a V/A switchable meter and a switching frequency adjustment to move interference birdies
I then labeled the panel (don’t laugh).
We then connected our ELAD FDM-DUO Software Defined Radio. We dug out a power/SWR meter from one of the storage boxes and hooked it up too.
We were able to receive WWV and hear a number of stations on 20m. We ran a tuning cycle and were rewarded with a bright green “tuned” LED.
Then we connected our Chinese miniPA50 and were able to join the Maritime Weather Net out of Washington state, NM1R and had a five minute conversation (QSO) with him.
Finally, we dropped down to 40m and ran a tune cycle; again, rewarded with a bright green “Tune” indicator.
Probably needs dressing up with some tie wraps or something. Feel free to make it look prettier! In any case, it now works, that awesome panel meter works great, and this project is ready for legions of ham radio operators/makers to operate.
Best regards,
Kevin
N5KRG
I was up at the space Saturday night. I brought in my new QYT-8900D and hooked it up to the dual band J-pole that’s ont he ham desk in electronics.
I was able to hear NOAA weather radio reasonably well. The DARC 88 machine was unreadable, although I could tell when someone was transmitting.
Just a couple of data points.
Todd
