What is a Transfer Relay?

Guest Writer: Bill True, WA9ASD

That’s when you get on a bus and buy a transfer so you can give it to your buddy to use to ride his bus to work for the cost of a transfer. Well, not exactly. If you Google “Transfer Switch” most of what you will find are AC power transfer switches. These are used to switch your AC power from the power company to your backup power source; generator, solar panels or battery backup. If you have a home AC generator your power company will require one and your local building codes people will have to certify it. It could be manual or automatic. We offer a Generator Transfer Switch. 

Is it a switch or a relay? The answer is confusing. My answer is as it pertains to Surplus Sales. A switch is a manually operated device.  Contacts are actuated with a twist or flip of a lever. It must be physically switched. A relay has a coil with a set of contacts operated by an armature. apply a voltage and cause a change in the position of the contacts. Switch: manual; Relay: electric.

Amphenol 300-11002-2 Transfer Relay

Amphenol 300-11002-2 Transfer Relay

An RF Transfer Relay allows you to connect 2 transmitters to 2 loads. One to a dummy load and the other to an antenna. When the relay switches the two transmitters are swapped between the antenna and dummy load. Another way to look at them is to consider a 2 position switch with ports 1, 2, 3 and 4. At rest port 1 is connected to port 3 and port 2 is connected to port 4. When activated the connections reverse. Port 1 is connected to port 4 and port 2 is connected to port 3. Broadcasters use these to connect both their main and backup transmitters to the antenna/dummy load for almost instant changeover to the backup transmitter. It can also be used to control the antenna connection to a transmitter and receiver. In the “at rest” position the receiver is connected to the antenna and the transmitter is connected to a dummy load. By switching on the relay when the transmitter is activated the antenna gets connected to it and the receiver goes to the dummy load, protecting it from the strong RF from the transmitter.

Another kind of reverse (perverse?) usage is to provide automatic grounding of an antenna when not in use. Whenever the transceiver is powered-up the transfer relay is activated connecting the transceiver to the antenna. When the transceiver is turned off the transfer relay de-activates connecting the antenna to ground. The same thing can be accomplished with a knife switch for open wire feed lines.

We have a couple of very high quality “N” Transfer Relays available from some of the most highly regarded manufacturers; Amphenol, DowKey and Transco (now a part of Dow Key Microwave). SMA Transfer Relays by DowKey. C connector Transfer relays.  EIA Transfer Relays for the Broadcasters.  Waveguide style Transfer Relays.

As you can see, transfer relays can be an important and valuable addition to your station. Call us if you have any further questions.

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Compass Technical Services – We spent a year there one month!

 

Compass Technical's armory stuffed collection - before the Grinnell tornado hit

Compass Technical’s armory stuffed collection – before the Grinnell tornado hit

September 11, 2001 was a date no American will ever forget. I personally embarked on a treasure hunt just a month after the disaster and the destination was Paterson, New Jersey, just across the Hudson River from NYC and the smoldering Twin Towers. It was a shocking environment relative to my home turf, Omaha, Nebraska. I made a deal to buy Compass Technical Services, a surplus business and small manufacturer of military equipment. The volume of a National Guard Armory, wall to wall, 2.5 floors. Loading started late October and we departed when my packing team mutinied on Thanksgiving Day. We had packed 29 semi-trucks over the month. One a day. Each maxed out to about 40,000 pounds. So the story goes.

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Teaching this old dog new tricks – Who needs social media?

I have been drug into the 21st century kicking and screaming. We always put out a decent catalog through the years. That is as far as small surplus houses are concerned. I bought the very first Macintosh 128, then a Mac 512 followed by a Mac Plus and on and on. BTW, we have never sold a retired computer. Not worth much. Great start for a museum. For software, Pager Maker was mastered and soon replaced the paste up catalog pages. If you’re not familiar with what paste up is, we literally clipped words and sentences out of catalogs, along with low res photos, pasted them all on an oversize page and added self adhesive black border lines. Then the printer would photograph the page and reduce it. Long about 1997 our last 400-page printed catalog fell to the Internet and our first website. My advertising department grew from one man to a two horse shop with a full time webmaster. That model more or less propelled me into the second decade of the new millennium.

Then a brick wall I did smack. The wheels fell off. We had not followed the rules. The website schematic that had proven fruitful for so many years all of a sudden took ninety ninth fiddle to more sophisticated sites and overnight our ranking on the average search slid to frightful depths down the search results. SEO. I thought that was like a Senior Executive Officer. Me of course. By the time I figured out it meant Search Engine Optimization, I was the last donkey out of the barn. Businesses exist whose sole purpose is to make web pages occur higher in the search. I know of several great companies that do just that in our Mastercraft Building. Perhaps I should have used one of them. Nah. That would be too easy. We can do all that ourselves. Eventually.

We are nearly finished with a full revamp and making our website more social media friendly and hope to be able to get back to selling parts like we have for 39 years. I will take a moment or two, from time to time, to write in this blog, and will try and share experiences that may be interesting to others. Many of us here at Surplus Sales will contribute. We have a collective 150 years in experiences to write about. Our intention is that new customers as well as those that have been around for the long haul might learn something about us that they didn’t know.

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Communication Speed in my 57 years

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When I was a teen I landed my first amateur radio ticket. WD0FDE. My FCC license to transmit on specific frequencies. The modes I used were phone / talking, CW / Morse code and teletype. Typical transmit speed was about 66 words per minute on the teletype and 10 wpm on the code key. In the 80’s I dabbled in packet radio which operated around 1200 bits per second. Then along came the Internet and ham communications took the back seat to a whole new world. I haven’t had a decent station set up since about 1981. Now I have 10 acres, component 1. Next I need personal time. Different story.

Trying to keep it simple and not confuse bits and bytes, my dial up modem for the Mac was 56k. That gave way to DSL at around 300k. As long as our service provider didn’t bottleneck in high traffic times, this speed was adequate for many years. New software, websites with more images and streaming video kept pushing me to acquire faster Internet speed. Today, in our Mastercraft Building, a building in Omaha that has about 90 suites for rent to entrepreneurs and creatives of all stripes, we have a program in place whereby a local service provider guarantees 1 gig bandwidth up and down speed to each a every tenant in the building for the price of dsl. Why I mention this here is because it’s a topic on everyone’s mind. Almost everyone interfaces with a computer, or wifi, every day. The speed of that connection can be the difference of an instant transfer where the connection was invisible, as in the 1G service, or a foot tapping bottle necked connection that takes forever.

The raw amount of data transferred in a typical minute of online surfing, when compared to my 66 WPM teletype, is staggering. The cost to my data transfer in 1975 was free, less the cost of my station. Today, in relative terms, what you get for your money, 1G (per second!) of bandwidth is almost free. It is nearly impossible to fill up a 1G fiber. Imagine being able to upload or download with no restriction in performance. Unfortunately, the rest of the Internet is not able to handle this speed, yet, so the bottleneck is there, it’s simply down the road.

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