Modern Mobile Rigs and AM

[K4QE]

I am planning to install an HF rig in my mid-size sedan.

I would like to hear any recommendations, comments, or warnings concerning the mobile rigs available today.  Specifically, I'm considering the following rigs:

Alinco DX-70TH
ICOM IC-7000
Kenwood TS-480HX or TS480SAT
Yaesu FT-857D

My priorities are low band performance (won't be crushed by BCB signals), AM operation (pleasing xmit and recv audio, not neccesarily HI-FI), and remote head capability (limited space available for a rig).

Others would be considered if they are more conducive to my needs.  I'm not interested in used or hollow-state rigs (I love tubes, but don't like to use them mobile).

Having VHF/UHF capability is unimportant, but it would allow me to remove my current 2 meter rig.

I'll be teaming it up with a Little Tarheel II screwdriver antenna.

Thanks in advance for your valued experiences and opinions.

[w3jn]

This belongs in the technical forum.  This forum is only for completed tips and articles.

[WA2TTP Steve]

I have the Alinco DX 70th which I have used mobile for the last 6 years without any failures but I wouldn't  recommend it for AM use. The receiver filters are not good at all in the AM mode. The filters are either to narrow or to wide. I have used it at times to listen to 75 AM and unless the signal is strong and has crisp audio the copy is poor. On SSB it works great. I've worked the world with it including VK's and ZL's on 75 using a HS 1500 screw driver antenna.

Steve
WA2TTP

[cx4di]

ICOM IC7000 is the best.

73´s
diego
CX4DI

[ve6pg]

...alinco dx70t(h) by far. i had an icom706mk2g, am receive is tooo wide...uses the fm filter....
  understand, i wanted the best sounding tx, and the alinco is the best. i've used all the others, and they are far too muffled, and distorted.
 the idea of a AM mobile rig is cool, but no one will talk to you if you sound like crap. if they do, they will tell you, that you sound like crap.
  my alinco has been in my car for over 2 yrs. never a problem. i'm using a hamstick, or pro-am for the hf bands. i did get an amplifier for it, and it works great.
 the one thing i've noticed on the alinco, is the noise blanker works very good. far better than the others i've tested.
 i have grounded all the doors, trunk lid, hood with bonding straps. i do use a filter on the dc line, as well. i have the dc cable for positive running right to the battery, and the negative lead to the frame. i did have the negative to the battery, but the noise dropped when i made the switch.  another thing to understand is, the impedance of the hf whips is very low. about 5-10 ohms. you need to correct this with a coil, which is easy to make, or purchase.
 you can fool the rig with a tuner, but you are best to correct the feed impedance, before you try using a tuner...lots of websites that deal with hf mobile operation. btw, all my mobile operation is on AM, and on 75, or 40 metres...tim....sk..

[WB2EMS]

I've run the DX70 for a number of years, and found it a great mobile rig. I got good audio reports from WA1HLR on 40 meters, despite downward modulation. The AM receiver bandwidth is a good match for our operation, around 6khz wide, maybe a little more. If you need tighter, you can hit the narrow button and it will switch in the 2.6 khz wide SSB filter, which will require you to tune off to one side a bit to get reasonable audio response while still passing the carrier, but that works good for trimming off interference on one sideband or the other. The controls are simple, a good thing for mobile operating, and the transmitter doesn't seem fussy about antennas. I normally hit the low power button to get 10 watts and transmit AM or FM for tuning the antenna and then go to high power. Made many 75 and 40 meter AM contacts with mine. Prices are pretty reasonable too. And you can find a cable to let you remote the head, either 6 foot or something like 20 ft. Its multiconductor and you could probably homebrew your own if you really needed to. The mic has to be connected to the radio body.

The 706 is a little complicated to run with the menus in the car. The AM receiver filter is terrible - they use the FM filter for that mode and it's too wide, I measured mine at 18khz at -6db points, and it has a lousy shape factor. You'll hear the whole window at once and them some. If modulation is run in the 13 pin connector in the rear, you can get reasonable audio reports on it. The stock mic doesn't sounds so good though. It gets hotter than the DX70, partly because of more receiver dissipation. If you are going to use a tuner and whip, the AH-4 is a good mate to it, it's what I use on a sailboat in the summer and the winter rat in the winter. I modified mine to add a proper AM filter using the directions posted on this website. As I recall it uses FL102 in one of the spare spots and modifies the steering diodes to make it available in AM mode. With that filter it works reasonably well. The cable to remote the head is thin, only 4 conductor and you can mount the mic on the remoted head. DSP is hardly worth while in it.

The FT857 is a bit newer and to me easier to run from the menus. I also like the layout and size. The head can be remoted and the cable is easy to build with 8 pin RJ45 connectors and UTP or flat cable. The mic has to be connected to the radio body. The receiver bandwidth seems pretty good for AM, wide enough for reasonable sound, not so wide that you hear too much on the side. I haven't made any AM contacts with it but yaesu's I guess are sometimes a little thin in the audio department. I've been told but haven't confirmed that they just use one sideband plus the carrier. The DSP is a lot more useful than the one on the 706, mostly because you can tweak the LPF and HPF cutoffs in it. Folds back fast when the SWR comes up. It's what I'm currently running in a temporary lashup with a screwdriver.

In the end, I'll likely end up with the 857 or DX70 in the main mobile setup. The 857 has more features and the VHF/UHF bands, but I usually have a separate FM rig in the car so I can listen to HF while monitoring the local repeater.

You didn't ask about antennas, but for 20 meters up pretty much anything works, hustler, hamstick,etc. But down on 75 you need a serious antenna. Bugcatchers seem to get the best results, with screwdrivers a close second. Capacity hats on either help.

[WU2D]

I am working with a couple of IC-7000's at work and so far I am impressed with the wider filters on FM and variable DSP filtering and audio options. There is no doubt that the quest for better audio and better digital mode data rate are very similar goals and this is beginning to show up in the toys.

But they are toys - when you go key down with the radio for while - it gets hot!

Mike WU2D

[N3DRB The Derb]

I got good audio reports from WA1HLR on 40 meters, despite downward modulation.

less carrier will fix that. I dont know if hat rig has a external carrier control or a internal pot but if it's a 100 watt rig on ssb, try it at about 15 watts carrier.