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Author Topic: Prius HF Mobile - 2 years later  (Read 3552 times)

Posts: 52

« on: July 23, 2009, 05:51:28 PM »

It works! For the past two years, between trips overseas, and one move, I have been slowly eliminating the Radio Frequency Interference caused by the Hybrid engine in my '04 Toyota Prius.

It has been a tremendous journey of reading, investigating, self-education and trial and error construction/assembly of shielding components, filters, ferrites, mobile antennas, mounts, wiring, power supplies and  vehicle construction. I think I went through over 100 yards of 3M 1181 copper foil tape and at least 50 ferrites  in the process!

As of today, my Prius HF and VHF mobile installation is working, operating effectively, and giving great reports on 20 meters. 20 is my favorite band and I was thrilled to hear and work stations throughout North America this evening. What a huge thrill!

I would like to thank Alan, K0BG for all his patience answering my numerous questions and providing guidance, hints and pointers, and to everyone else in this forum who commented at one time or another.

Some "neat" things I discovered while out on a test drive tonight.

1. People stop and stare at the antenna. I struck up a conversation with one stranger who thought it looked cool and at least one person took a photo of my car with the roof mounted HiQ.

2. I can hear all kinds of noise and signals as I drive through the city, and some vehicles are "downright noisy" on HF - I can hear them as they drive by!

3. A drive in the countryside with the HF radio on is 'fun'. The city noise drops away and signals "pop out" at S9.

4. I've learned to watch out for low hanging trees. they make the antenna go "Twang".

5. A new and fascinating dimension of our hobby has enthralled me. I was even thinking about a mobile amp on the way home :-))

There is much that I need to do, including posting some of the numerous photos  of the modifications I undertook, along with write ups and explanations so that others can benefit, and I will do that over the next few months.



Posts: 203

« Reply #1 on: July 23, 2009, 08:25:52 PM »

Congratulations! This is a great accomplishment, requiring much skill and perseverance. I do hope you will write a detailed article, since you are now the authority on this subject. As hybrids become more common, your work will be a major contribution to our service.

I would be daunted by a mobile amp, given both its power requirements and the potential for incoming RFI in your car. But, hey man, you've made it this far!
Good luck and 73,

Posts: 1484

« Reply #2 on: July 25, 2009, 05:41:24 AM »

Please do put some photos and descriptions on the web--I'd love to see this!  It sounds like you've overcome a huge set of problems to get this working.

I've finally got a working 706 installation in my early Scion xB.  I don't recall this from the last time I was HF mobile (2002-3) but you're right about how much noise there is in the city.  THere's one spot on my commute where I often listen to local 2-meter repeaters because some warbling/buzzing noise on 20meters is S9 for a couple of miles.  :-(

HF from the car is FUN, though, isn't it?

Posts: 10

« Reply #3 on: August 12, 2009, 11:08:26 AM »

I gave up on my 2004 Prius, gave it to my son, and got a BMW.  Now I'm very happy, but have to spend more on gasoline (so what).  What I never could understand is HOW can the AM radio on the Prius not hear all that RFI?  There must have been some interesting design factors to enable a noise generator like the Prius to be completely quiet on the AM broadcast band.  I listened on 160 with an 80 meter screwdriver antenna and was not able to hear and RFI there, either.  Any ideas?  Regards, John W9NET

Posts: 52

« Reply #4 on: August 13, 2009, 07:45:42 AM »


for some reason, the design of the DC-DC inverter produces RFI from about 2.5 to about 15 MHz.
Suppression of the HF noise was difficult, I did some mods inside the DC-DC inverter(added filter capacitors and ferrites, plus a LOT of bonding and grounding. I'm not sure many hams would go to such extents. While there is still some RFI noise, it is down to abt 1 S unit, except for a short pulse type noise that appears every time the Electric motor kicks in. While i have some ideas on removing the residual noise, I am quite happy with the results so far. My coolness factor with my teenaged kids whent way up when I was having an 'Armchair copy' QSO with a Station in Munich while driving them to a friends house.

Moounting the antenna in the centre of the roof was a challenge, and involved drilling holes and removing the headliner to add in re-enforcing plates, but the results were worth it.  The antenna is a HiQ 3.5 with capacity hat and 5 ft whip. I sure get a lot of stares, mind you.

I have some Spectrum Analyzer screen shots that show the noise spectrum. With the roof mounted screwdrvier I have had no problem working DX on 20.

Eventually I'll get around to writing this up as an article that I can post to a web page.


Posts: 4

« Reply #5 on: August 28, 2009, 04:33:19 PM »

I look forward to seeing the pics of this install!  Congrats!
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