The ham responsible all but vaporized a nice Flex Radio HF transceiver, power supply, and the electrical wiring in his camper. LUCKILY, nobody was injured, but it could VERY VERY EASILY have been much worse. You don’t get a second chance with contacting power lines.
No no of course not, you can’t burn things with RF unless they’re inside the microwave.
Presenting WMBM-AM, Miami Beach, Florida.
The tower stands in a courtyard behind Radio Bar. The courtyard is fully enclosed. Except…….. The bar uses it as an entrance and exit and storage area and leaves it open to the public.
Sorry for blur in these images, I was unable to stop laughing.
To the right just inside.
To the left just inside.
Note that this tower is not on insulators. It is [barely – see below] grounded. The transmitter output goes to a three wire skirt that starts well up out of reach and is fed by, uh, let’s visit that later
Kinda sorta ground. One small wire, about 6 gauge.
See that red square? That’s the transmitter output. Right there. It’s like seven feet up in that corner. You can see the two pipes in the photo above. Only a chain and defaced warning sign (not even a standard RF exposure warning sign) separate bar guests and that.
Possibly remains of an older feed to the tower…. even more exposed.
No, the tower lights don’t work.
This has apparently been how it’s stood for years.
On a side note, here’s an at&t installation. The old vault is on a berm above ground to protect it from storm surge. The VRAD, used to supply PooVerse I mean UVerse television, internet, and kind of sort of phone, not so much.
I could write volumes on how awful and ridiculous this box is, but… Here, I summarized it in one image: if you add thick eyebrows, a moustache, and a goatee to it, it looks every bit as malevolently untrustworthy as it truly is. They’ve been out of production for a long time (cheers were probably heard all over Quincy when the order to discontinue them was made) and certain key parts are looooong gone.
First off, our radio knobs were too easy to turn, causing them to get unexpectedly muted or knocked off channel.
Second, I fail so hard at shitposting. I always want to just fire up WordPress and drop a useless shitpost on here then I think of something actually useful and informative. What follows is a failure to shitpost.
I’m still not exactly calling this a great post because I’m too lazy to edit the images.
Step one: pull the knobs off. Pull straight up. The knob may be tight on the shaft, just don’t apply excessive force in any direction if it is. Be patient. On this Hytera it was pretty easy to pop off.
The recess here is what we’ll be modifying. Cut two little circles out of craft foam, mouse pad, inner tube… Whatever rubbery thing you have handy… Or use rubber o rings. It don’t matter.
If there’s no hole in them yet, fold in half and cut a slit.
Press it down the shaft and all the way into the recess.
Reinstall the knob. Test to see that it moves and has more resistance. If there’s no effect, add another layer. If it doesn’t fit back on there, remove it and try a thinner material.
This took me about two minutes per radio I did it on and eliminates annoyance like nobody’s business.
The first time I did this mod was on a Baofeng, so I’m gonna add the shitpost tag. You’re welcome.
For future reference to myself and everyone else, so I don’t have to keep searching my email every freaking time:
On the Harris Z series transmitters, the SCRs used on the rectifier board may be either one of two kinds. They may be a current part made by Littelfuse or a discontinued one made by (this has escaped my memory banks, sorry!)
If you have the newer board, you have Littelfuse S6055R SCRs on it. If you have the older board, your SCRs can be replaced with the S6055R. If you’re me, you replace them with the S8055R, which is the same part in every way EXCEPT that it can handle 800V reverse voltage instead of 600. (Probably comes in handy in avoiding blowout during power surges?)
Troubleshooting: You will receive fault code PSx_TAPy where x is the power supply number and y is the tap number. Try clearing this fault as it may be set by a voltage transient. If it recurs in the same place, disconnect ALL power to the transmitter and pull out the power supply drawer from the bottom. You will need a second person’s assistance. I found it easiest after removing the blower from the back as well. Test each fuse on the rectifier board identified by the fault. If you find blown fuses, change them and try again. If you find fuseholders that look like they’ve been hot, change them.
However, if the fault persists and the fuses and holders are all good, change the SCRs. Using a vacuum desoldering iron will help a lot. I used my Hakko 808.
There’s a RF spectrum analyzer in there. Now, it’s not a GREAT one, the minimum frequency resolution is a big wide 6 megacycle wide sweep…. but it’s there.
Overall view, you can see the bands used for upstream and downstream, divided by a blank band around 100.
That band has some spiky bits in it. What are they? Well… I live within walking distance for the transmitters for a couple of 100KW ERP FM’s…
ENHANCE! There’s 93.5 “The Bull” W228BV-FX; 106.7 WDXJ-FM + HD, 105.9 WBGG-FM, and a few others, all leaking into the cable system at fairly harmless looking levels. I suspect Comcast simply leaves this band of spectrum empty on their cable system to make life easier in the face of RF leakage. (??)
I’ll code a GUI interface in Visual Basic…
The view goes in just enough to make the analog carrier and HD sidebands of WXDJ-FM visible and distinct. It looks like the lower one MIGHT be suppressed a bit – this is an interference mitigation feature present in modern HD exciter firmware from Harris/GatesAir, Broadcast Electronics, and Nautel. You can back it down a bit to be all cool and avoid adjacent channel interference.
I dunno — you can’t expect a spectrum analyzer built into cost engineered nasty home internet CPE to be the best thing ever, but it’s still fun to play with.
I wonder if the Tytera MD-390 will have fixed some of the oddball bugs from the MD-380? One notorious one that’s come to light recently is that if you un-key then key up again shortly afterwards, the radio’s transmitter timing slips and it’ll scribble over the opposite timeslot. Sounds like a show stopping bug and I’ve seen it blamed on a bug in the Texas Instruments DSP chip at the heart of the radio, which… I’m not inclined to believe.
Either way, even if it was, it’s not like there haven’t been software workarounds to hardware bugs that work successfully before. Just look at the Linux kernel – it’s got a LOT of fixes for CPU/chipset issues which would otherwise be show stoppers.