Hi-Q HF Antenna & FT-891 Install on a 2 Door Bronco

[Kilgore]

Did another test layout of the equipment in the tray. Looks like it will all fit with plenty of air circulation space.

As I mentioned on an earlier post, an engine start drops the voltage low enough to bring in an undervoltage alarm on one of the radios. I needed to address this before finalizing the tray and drilling holes.

One solution was to include either a small gel cell battery or a capacitor and diode across the supply to support the voltage during the engine start.

Digging around my parts, I found a capacitor that should do the job, 18,000 microfarad @35 volts. As a trial, knocked together a test circuit comprised of the capacitor, a random diode, and gave it a try.

The results were good. During idle, the radio saw 13.9 volts, and during a start, the minimum was 11.7 so it looks like it will work. The final version will include a diode rated for the full draw of the equipment and a low forward voltage drop. Probably a schottky diode. The tray photo shows the capacitor in place in the lower left.

With this behind me, the metal work can continue.

Sponsored

 

[Kilgore]

All the holes are done. Next job is to weld up the box and make it look pretty.

 

[Kilgore]

The pan is all welded up and wearing a coat of paint. Next comes the baseplate and lid fabrication

Have been collecting the welding cable and high current fuse blocks for the DC feed. Will be fabricating a plate/bracket to mount the blocks and disconnect relay in the engine compartment.

 

[Mammal]

The pan is all welded up and wearing a coat of paint. Next comes the baseplate and lid fabrication

Have been collecting the welding cable and high current fuse blocks for the DC feed. Will be fabricating a plate/bracket to mount the blocks and disconnect relay in the engine compartment.

stoked to see this update!

Do you go with welding cable for cost savings?

when will the disconnect relay activate?

 

[Coldsmoke]

This thread seems like the perfect place for a "Mine's bigger" comment.

 

[Kilgore]

stoked to see this update!

Do you go with welding cable for cost savings?

when will the disconnect relay activate?

I like to use welding cable for these high current installs because of its great flexibility. This install will need to accommodate the addition of a 500 watt HF amp in the future, so the DC supply needs to be robust. I have used a lot of EPDM insulated cable in the past with no issues. It's also covered it in a nylon flex sleeve for abrasion resistance. For this install, it will be #4 wire based on voltage drop.

https://a.co/d/dXy7gFe

A great resource for sizing DC cables is provided by Blue Sea Systems and can be found here.

http://circuitwizard.bluesea.com/

Ford did us a favor by including high current lugs that would normally be used for a winch, but it will power the radio equipment instead.

The disconnect relay will be controlled by one of the auxiliary switches above the rear view mirror. It's rated at 200 amps continuous.

 

[Mammal]

I like to use welding cable for these high current installs because of its great flexibility. This install will need to accommodate the addition of a 500 watt HF amp in the future, so the DC supply needs to be robust. I have used a lot of EPDM insulated cable in the past with no issues. It's also covered it in a nylon flex sleeve for abrasion resistance. For this install, it will be #4 wire based on voltage drop.

https://a.co/d/dXy7gFe

A great resource for sizing DC cables is provided by Blue Sea Systems and can be found here.

http://circuitwizard.bluesea.com/

Ford did us a favor by including high current lugs that would normally be used for a winch, but it will power the radio equipment instead.

The disconnect relay will be controlled by one of the auxiliary switches above the rear view mirror. It's rated at 200 amps continuous.

Awesome! Thants for the link to the calculator! I’ve always spent considerable time on those calculations in the past.

So is the disconnect for main power supply to everything in the box you built? Or just the amplifier?

 

[Kilgore]

The relay isolates all the comm equipment and rear auxiliary battery from the charging system. It's rather embarrassing to drain the vehicles battery while having a chat on HF!!

When using the amp, you have to have the engine running to support the voltage. It draws 80-90 amps on ssb voice peaks and looses 85 watts per volt below 14V.

 

[evilernine]

I am new to the Bronco and looking for Ideas for mounting my Lil Tarheel II antenna and radio that was removed from my 2014 JKU. The antenna was connected to an Icom 7000 and Turbo Tuner. I also ran a Kenwood TM-D710A VHF/UHF with a Mobilinkd (http://www.mobilinkd.com/) bluetooth TNC and an Android tablet running APRSDroid for APRS.

Following this post for sure.

Bryan - K7GX

 

[TNTACO]

Look at it like this. GMRS is a tool that off roaders use for their hobby. Ham Radio IS a hobby of its own. When you combine the two, IT IS AWESOME! As soon as I get my Wildtrak (build week of 04/08/2024), that is the first upgrade. Putting my Icom 7000 and Tarheel antenna on. I am in the same boat as far as where to mount antennas. I will need to mount the Tarheel and a UHF/VHF antenna. Originally I wanted to mount both on the back but I am second guessing that. I don't keep the HF antenna on all the time. Only when I am traveling. Decisions, decisions. N3CRS.

 

[Mammal]

The relay isolates all the comm equipment and rear auxiliary battery from the charging system. It's rather embarrassing to drain the vehicles battery while having a chat on HF!!

that’s a lot of power per volt!

When using the amp, you have to have the engine running to support the voltage. It draws 80-90 amps on ssb voice peaks and looses 85 watts per volt below 14V.

That all makes sense. I missed that you were installing an Aux battery. I had a small aux battery on my 2m/440 low pwr rig in past truck. Used the west mountain radio isopwr to keep it charged.

Is there a risk of (too) large a current rush should the aux battery be depleted and the relay connects to the charging system/main battery? Or does your large welding wire accommodate for such an occurrence?

Thanks for fielding my questions. Your experience is quite a resource.

Sponsored