Alfonso Faustino: Motorola XPR 7550e: BNC Female Antenna Adapter (Connector)

My team and I created a BNC female antenna adapter (hereinafter, antenna adapter or BNC antenna adapter) for the Motorola XPR 7550e, Motorola XPR 7550, and the Motorola XPR 7580.

Our BNC antenna adapter:

– matches the polarity of all the Motorola XPRs,

– has an RF ground for coax connections to external antennas and car-mounted antennas, and

– has been tested by a Motorola technician, using the Aeroflex testing unit, showing our BNC antenna adapter does not interfere with the performance specifications of the Motorola XPRs. (The areas of interest, along with other measurements, was ensuring the Motorola XPR was still putting out 4 watts on the analog side; and, at least 2 watts on the DMR side with our BNC antenna adapter connected to the transceiver.)

With the BNC antenna adapter my team and I created, I can use non OEM Motorola rubber-duck antennas, such as, the Diamond SRH320A, with my Motorola XPR transceivers.

In the picture below, I’m was reviewing the RSSI with the Diamond SRH320A hooked up to my Motorola XPR 7550e UHF, via our BNC antenna adapter. I’m was hitting an analog repeater in San Francisco called, CARLA System 2, which is within two ground miles east of location, Eagle’s Nest. I was in my bedroom.

If I want to use my standard OEM Motorola antenna, I just unscrew the BNC antenna adapter, and I screw in my OEM Motorola rubber-duck antenna, like this stubby, shown below, to my Motorola XPR 7550e UHF transceiver.

In the picture below, I’m was using my BNC antenna adapter with a coax that connects to my car-mounted antenna. Now, I can use my Motorola XPR 7550e UHF when I’m in my car.

The cost of our BNC Antenna Adapter for the Motorola XPR Hand-held transceivers is $25 USD.

In the picture below, I’m was hooked up to my rooftop antenna, Diamond x50, and I was reviewing the RSSI with our BNC antenna adapter screwed into my Motorola XPR 7550e UHF transceiver. I’m was hitting CARLA System 16, which is located in Sacramento, California, which is ~ 70 ground miles Northeast of my location, Eagle’s Nest.

Email me for orders or questions:

In the picture below, I’m was using the BNC antenna adapter with my Motorola XPR 7550 VHF transceiver. I was connected to the coax of my external roof-mounted antenna, Diamond X50, and I hit a repeater, K6BW, which is located in San Anselmo, CA.. I was talking to the owner of the repeater, and he was impressed with my transmission qualities. San Anselmo repeater is ~ 47 ground miles North of Eagle’s Nest.


/s/ Alfonso Faustino (K6ASF)

Craftmanship Of Our Motorola XPR 7550e, Motorola XPR 7550, Motorola XPR 7580, and Motorola XPR 7580 BNC Female Antenna Adapter (Connector)

Our BNC Female Antenna Adapter (Connector) for the Motorola XPR 7550 – Motorola XPR 7580 transceivers are made in the United States.  We assemble the adapter by hand using the same materials as the OEM Motorola Antennas.

Many people tell me they can get the same product on eBay for $2 to $5…I tell them, “go right ahead.” I certain if you buy it on eBay or elsewhere online or at a store, most likely, they have not been tested nor be the correct adapter/connector for your Motorola XPR transceiver.

How do I know this?

Because, I made purchases on eBay and elsewhere; and, the products I purchased did not properly match the specifications for the Motorola XPR.

To make one adapter, it takes us about 40 minutes to assemble and properly size the adapter to the Motorola XPR transceiver.

How did we get the exact specifications for the Motorola XPR transceiver?

We got the build-specifications from a former Motorola employee that worked as an engineer and technician at Motorola USA in Illinois.  He is now retired and has been extremely helpful to me and my team.

The materials we use are high-quality — especially, the antenna bolt.  The antenna bolt is difficult to find; because, it MUST match the polarity of the Motorola XPR — if it doesn’t match the polarity of the Motorola XPR transceiver, you will not get a good RX and TX; and, furthermore, you might cause damage to the capacitors in the Motorola XPR transceiver.

We spent a lot of time studying the Motorola XPR transceiver; and, we spent even more time taking that information and applying it to the building or our BNC female antenna adapter (connector).

Since the Motorola XPR 7550 and 7580 were purposely designed not to accommodate non OEM antennas, we had to apply our RF engineering knowledge into the build of our BNC female antenna adapter (connector)…this led to the creation or the RF ground designed to our antenna adapter.

It is my opinion, Motorola wanted to increase sales to their mobile transceivers, such as the Motorola XPR 5550.  In order to increase sales, they removed the SMA pin, which was found in their preceding model, Motorola XPR 6550, and moved the SMA pin into the OEM Motorola antenna.

By doing this, customers would be forced to purchase the mobile units instead of connecting their hand-held XPR 7550 and XPR 7580 transceivers to the coax of their car-mounted external antenna or an external roof-mounted antenna.

The Motorola XPR 6550, which is now discontinued and replaced with the Motorola XPR 7550, was the last hand-held transceiver that had the SMA pin built into the Motorola XPR 6550’s body; hence, many owners of this model enjoyed the freedom of expanding the range of their Motorola XPR 6550 with the use of a car-mounted or roof-top antenna.  Because of this, there was no need for an operator to purchase Motorola’s mobile units.

Because the Motorola XPR 7550 and Motorola XPR 7580 do not have the SMA pin built into the body, we needed to create an RF ground for our BNC female antenna adapter (connector).  Without the RF ground, we run the risk of interfering with the RF specifications of the Motorola XPR 7550 and Motorola XPR 7580.

So, in order to keep within Motorola’s RF specifications, we created the RF ground for our adapters.

After many hours of engineering theory, material studies, and industrial design, we came up with our final product.

Sure, it looks like the stuff you can get on eBay or elsewhere; but, believe me…it is nothing like the stuff you see on eBay or elsewhere.

Before putting it out to market, we had to test it.  Two of my team-mates are experienced engineers and have engineering degrees; they have many years of experiences in RF and microwave engineering; hence, they have extensive equipment to put our adapter to the test…my Motorola XPR 7550e (UHF), Motorola XPR 7550 (VHF), and my Motorola XPR 7580 (800-900 mHZ) were the test subjects.

We tested it with dummy loads, antennas, various lengths of coax, many different rubber-duck antennas, and so on.  We also tested the adapters through hours of use.  It passed our test parameters — no interference with Motorola XPR 7550 and Motorola XPR 7580’s RF specifications; and, most importantly, no over-heating — all the transceivers stayed cool — great news; because, heat is one of the signs of problems when using a bad antenna or mix-matched antenna.

After conducting our tests, we had to make sure our numbers and test results were accurate; so, we brought our antenna adapter and my transceivers to an authorize Motorola dealer and technician.  The technician hooked up my transceivers with our adapter, and he tested the transceiver and our adapters before and after the antenna connection with an Aeroflex testing and tuning machine; and, our BNC female antenna connector with the RF ground passed — no congestion, no spill-back, no over-heating, and not interference with Motorola XPR 7550 and Motorola XPR 7580’s RF performance specifications.

By this time, about two months had passed, and we were finally able to introduce our product to our HAM network in the San Francisco Bay Area.  Our first sale, went to the president of the San Francisco Radio Club; our second sale went to a HAM operator in Massachusetts, and, other sales went to international HAM operators.

We now have a back-log; and, new orders won’t be available until the end of October 2019.

Since we are a small operation, we have to assemble our units by hand; and, after being assembled, each unit must be tested to ensure they meet Motorola’s RF specifications.  Once the units pass the tests, they go through performance testing by staying on my transceivers for a full 24 hours of RX and TX use on DMR and analog.  I also test their performance connected to a coax for the second 24 hours.

After 48 hours of testing, the units are ready to be shipped out to the owner.

We are truly happy with our product; and, the benefits I’ve had using the Motorola XPR 7550 and Motorola XPR 7580 BNC Female Antenna Adapter (connector) have been invaluable; as, well as cost-effective; because, now, I don’t have to fork up money for an XPR 5550 mobile unit.

If you have any questions, feel free to contact me: K6ASF at yahoo dot com.

Check 6!

/s/ Alfonso Faustino (K6ASF)

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