These connectors appear on the backs of various FM and lower-power TV transmitters. I thought it would be interesting to explore them a little bit.
First, according to Wikipedia, DIN is an abbreviation for Deutsches Institut für Normung. If you enjoy a lager or two then squint at that name you might see The German Institute for Standardization. 7 is the size of the inner conductor contact in mm and 16 is the size of the inside diameter in mm of the outer conductor. The thread is 29 x 1.5 mm.
From what I can find, the connector was originally developed for the German Military, which needed a rugged, efficient connector that was easy to install properly.
This style of connector is very popular with cellular antenna manufacturers due to its relatively high power handling capability and excellent passive intermodulation performance.
According to Amphenol, their 7/16 DIN connectors have the power handling capability of 3000 watts/1 GHz @ 25C (77F). That is a fairly low temperature. They give the working voltage as 500 V RMS continuous, which is 5000 watts at 50 ohms impedance. That, of course, assumes a 1:1 match, which is never the case. The connector is probably safe to ~2 KW in normal operating conditions for VHF and UHF TV operation.
Amphenol 7/16 plug for LMR-400 and Belden 9913
Also, keep in mind that RG-8, RG-213, RG-214, LMR-400, and Belden 9913 look similar but they use different connectors because the inner conductor of the latter two is larger than RG-8, RG-213, or RG-214. This happened on a project recently. It came time to crimp the pin on the center conductor and, oh no! The pin was too small!
A properly installed connector will be outdoor water-resistant in most weather conditions.
I have been reading about WWNC Asheville, North Carolina in the aftermath of Hurricane Helene. That is an AM station on 570 KHz (5 KW DA-N) owned by iHeart Media. They have been simulcasting on all of the local iHeart signals in the area and according to WRAL-TV, have been the only source of information for people who have been cut off in the mountainous areas.
While the power is out, wired telephone service is down, cellphones and mobile data are unavailable, AM radio still gets through. Yes, FEMA has satellite phones and can work with commercial wireless providers to re-establish wireless networks and connectivity. However, it often takes them days to react and weeks to get on site.
Stations like WWNC that stay on the air during disasters are vital resources to their communities. The fact that they remain on the air requires planning and forethought. Emergency power at both the transmitter and studio is the most important and most expensive thing. After that, backup programming feeds and sources, secure shelters for personnel, food, water, and even spare clothing. Having experienced several of these events; Bill Ruck in his Radio World letter said it best, Engineers need to take care of themselves.
That means not taking excessive risks during the event, eating properly, and getting adequate sleep. Lack of sleep can lead to poor decision-making processes, making matters worse.
Sometimes transmitter sites are inaccessible or completely destroyed. Having a plan ahead of time to get some signal on the air is always a good idea. Sometimes an area is so severely impacted that there is no normalcy. Things that we take for granted are simply gone. I found the best way to deal with this is to take a step back, take stock of the situation, if you can find others who are working on disaster relief, coordinate with them, come up with a plan, then proceed carefully and be ready to adapt as the situation requires.
The next Hurricane; Milton, is taking a line towards Florida.
The Hurricane Watch Network will be active tonight at 14.325 or 7.268 MHz starting at 5 PM EDT for Amateur Radio operations and Shortwave Listeners.
WX4NHC is the Amateur Radio station for the Hurricane Warning Center. They have useful information preparedness, information gathering, and post-disaster response.
I found this obviously used GPS antenna in a storage room at one of our client’s transmitter sites.
How often have you asked that same question about some older piece of equipment lying around? There is a trend among engineers to hold off on getting rid of old equipment because someday, perhaps, it can be used again. Often, these treasures so lovingly stored away for many years or decades do not work when that day finally comes along, leading to disappointment and despair.
This GPS antenna falls into that category.
What to do, what to do…
Fortunately, there is an easy way to test this antenna and do other things with GPS. I had one GT-U7 GPS receiver module left over from a previous project.
Couple that with an FT232RL FTDI USB to serial converter and a bit of software from u-blox. The GPS receiver is a clone of a u-blox M6 GNSS chip, meaning the u-center software will work with it. That is a free Windows software application. The u-center software is great because you can access all of the options on the GPS receiver chip. Since this is to be used for testing, I enabled the LNB voltage sensing and protection features in the antenna configuration menu. Thus, the software will notify if there is a short circuit or open circuit in the GPS antenna under test.
GPS survey receiver parts
I had this nice Hammond 1590WB diecast enclosure left over from a previous project. It’s probably a bit of overkill, any small enclosure would work, but why buy something new?
Mini USB 2.0 Cable, USB A to B Cable, 3 feet, Amazon B00006B6PH, $3.95
The cross-connect between the two modules is fairly straightforward:
GT-U7 pin
use
FT232RL pin
use
2
TXD
2
RXD
3
RXD
3
TXD
4
GND
5
GND
5
VCC
4
VCC
Pin out
Internal mounting
This particular FTDI module has a jumper to set the VCC to 3.3 or 5 volts DC. I left it on 5VDC to run the GPS receiver and provide LNB power to the connected GPS antenna.
I used a piece of packing foam tacked into the inside of the enclosure with gorilla glue, then tacked the FTDI module to the foam with gorilla glue. The GPS module is tucked under the header for the FTDI chip.
The software is pretty easy to use. The most difficult thing is figuring out which com port and baud rate to use. To find the com port, open the Windows device manager then plug the FTDI module in. The new serial device should register automatically. Click on the new device to get the com port information. I find the GT-U7 modules are most often set to 9600 from the factory, but it could be anything. I suggest trying different baud rates until you start seeing data.
Putting all of those things together, we get this miniature USB power GPS receiver with software that can show how well a GPS antenna is working and whether or not the location has good (or good enough) reception. One could also check the coax going to a GPS antenna and make sure that it is working right and not too long. Or check and see if a line amplifier is working, etc.
The answer to the above question is, yes!
u-center software screenshot, GPS antenna under test
The used GPS antenna is picking up plenty of signals from a less-than-optimum position. I’d say this is a keeper.
Device under test; GPS antenna on window sillGPS survey receiver
A little bit of orange paint, also left over, and a few labels and it looks like a professional unit. Not bad for some leftover parts I had lying around.
I finished up another GatesAir FLX-10 install recently. This one was way out in Provincetown, MA at the end of Cape Cod for WOMR (Outer Most Reaches). That is a community radio station that has an eclectic mix of programs. The studios are on the second floor of an old church.
Main studio, Wheatstone ConsoleTalk Studio, up/down studio furniture
The transmitter site is located about a mile away from the studios.
WOMR antenna
A few details on the installation; the antenna is mounted on the water tank, which is the tallest thing around for many miles.
WOMR antenna, Shively 2 bay 6810 mounted on a water tank
The building is less than 120 square feet, which made working a little tight.
WOMR transmitter building, Provincetown, MAGatesAir FLX-10 transmitter placedPump Station
There was very little room outside for the heat exchanger because of the need to get vehicles around the water tank for maintenance. The area around the building was taken up with a generator and HVAC gear. We ended up mounting it to the side of the building horizontally. The main reason was that the wind at this location could come from any direction. If mounted vertically, there was a chance that the wind could blow into the heat exchanger against the fans, possibly causing some overheating problems. Also, the horizontally mounted unit will have a smaller surface area during Hurricanes and Nor’easters.
Heat Exchanger, mounted horizontally on the northeast-facing wall
To do this, I made a unistrut frame and attached it to the outside wall.
The liquid-cooled transmitter takes up much less floor space than the prior transmitter, a Nautel V-10. This installation also included activating an HD Radio signal for this station.
The GatesAir FMXi4G importer/exporter resides at the transmitter site. Currently, the station has HD-1 on the air, no word on any future sub-channels.
Looking North towards the Atlantic Ocean
We had nice weather on one of the days. On the last day (Friday) it was raining with 35 MPH wind guests.
Speaking of Marconi, the US’s first trans-Atlantic wireless transmission station is a few miles down the road in South Wellfleet. Nothing is left of the site; time and erosion have taken all traces away.
Postcard, South Wellfleet Marconi StationBronze plaque placed in 1953 by the Wellfleet Historical Society
Here we are standing on the location of the transmitting building. The last two tower bases tumbled over the cliff edge in 2011.
It’s always an enjoyable time installing a liquid-cooled transmitter!
