Cross-Band Radio Repeater – Part #2

cross-band repeaternote: first appeared in early 2015

I really saw a need for “repeater” capability when a bunch of individuals got together and all they had was handheld radios.  Distance and Line-of-sight always limited their usefulness.  And when it came to responding to a disaster or emergency situation handheld radios are virtually essential.  But once again, they have limited transmit and receive capability.

When I stumbled upon the Baofeng UV-5R handheld radios <click for more info> a few years ago I knew I had in my hands an invaluable resource for “preparedness”, especially after “grid-down.”  I cannot stress enough what the ability to communicate will mean then or even during less dramatic disaster situations, or even while hunting or camping.  I was aware of “repeater” technology through my government day-job but it was appeared to expensive and complicated.

When I first got my Ham radio license I began my search for the best all-purpose radio that my budget could afford.  That took me to decide the Yaesu FT-8900R <click for more info> was it.  Once I dug into it I realized how easy it was to set it up for cross-band repeater operation, I knew I had the answer in my hands.  However, I decided a used Yaesu FT-8800R was a more economical solution for setting up a field-going repeater.  And that led me to this “build” and documenting it for you in this article.

In Part #1 I covered the first five steps, in this post I will conclude the build and summarize my experience at the end.

Yaesu FT-8800r based cross-band repeater.

Finished Product – Complete with the Yaesu mounted inside.

 

Step #6 –

Yaesu FT-8800r based cross-band repeater.I am installing the remote head separate from the radio body.  This is to allow the rear of the radio unit to be accessed from the front of the box.  And it allows the radio to run a bit cooler since the head is separate from the body.  To get the remote head installation bracket properly installed I used a piece of 2″ aluminum angle to give the bracket a solid mounting surface.  All mounting bolts utilized star washers to prevent the nuts from inadvertently spinning off. The remote head is mounted as “dedicated” for the repeater and will not be removed for any other usage needs.

Step #7 –

Yaesu FT-8800r based cross-band repeater.This was the easiest of all brackets to mount.  My only concern here was mounting the microphone bracket where the microphone would easy to grab while keeping it out of the way of the rest of the box contents, including the wiring.

 

Step #8 –

Yaesu FT-8800r based cross-band repeater.Last came putting it all together as a complete ready-to-go repeater package.  Couple notes:

  1. I had double fuses in the box.  The power cable coming in had a fuse on the positive and negative.  Then the power (+) cable to the radio had a fuse as well.
  2. Notice the short antenna coax jumper cable from the “through-the-box” double male 239 to the rear of the radio.  I used an 18″, I could have used a 12″.  Using an 18″ would enable me to remove the radio unit and set it on top of the box for troubleshooting or any other reason.
  3. I built my own remote head cable since all the commercially built cables were really long.  I didn’t want all that cable coiled up in the box so I built my own 6-wire.
  4. All my wire connections are Anderson PowerPole.  I use them for everything and doing so here ensured compatibility now and in the future whatever change might come…including repairs if needed.
General Question & Answers (questions from folks that have seen the repeater) –RadioAntennaCar
  1. Can a magnetic mount external vehicle dual-band antenna be used with this repeater?  Yes.  Since the antenna connection on the exterior of the box is a standard 239, basically any antenna can be used with this unit.  I slapped a Tram 1185 Amateur Dual-Band Magnet Antenna directly to the metal box and it worked just fine. It gave the repeater a very low profile and hard to spot.
  2. What antenna do you use with this unit?  I built a highly portable antenna for use with this unit whether using it as a repeaters or as a base unit.  I built it to blend in with the desert surroundings here in the desert southwest.  I will post an article about that soon.  But any dual-band antenna will work.  The heart of the antenna was a J-pole designed by Dr. Ed Fong WB6IQN of UC Berkeley, featured in the Feb. 2003 issue of QST.
  3. What do you use to power this unit?  I built it to work with the 12v 105 amp hour Energizer AGM gel battery I purchased through Sam’s Club. I expect the radio would operate about 1 – 2 days without the need for charging. I have two 30w solar panels with a charging unit to hook up to the battery.  A GoalZero charger controller handles regulating the battery charging.  I can run the unit with my Honda EU2000i if need be.
  4. You mentioned “base station”, explain?  If I am not needing a repeater, I can use this unit as a base station. I just leave the lid off and place the box where I don’t have to lay on the ground to use it.  It has everything needed to be able to operate it just fine as a base station.
  5. Do you set it on the ground to use?  No, not really.  I would set it on rocks to get it up off the ground.  I am working on a lightweight aluminum stand with folding legs to keep it about 6″ off the ground.
  6. What water-proofing have you done to the box?  Not much.  The box itself is extremely sturdy and the lid has a rubber seal.  All the screw/bolt heads that protrude on the exterior of the box have all have silicone seal on them.  The vent holes are the weak-link; fan and intake.  Not much I can do about that except maybe place a cover over the box that would act like a roof.  I might consider that when building the stand for it.

If you love your handhelds for ease of use, you will love this repeater to extend the range of your beloved handhelds.  Enjoy!

 

 

 

 

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