Hi Peter,

Welcome to ham radio. I too have a 706MK2G. It's a unique little radio that covers a wide frequency spectrum. To answer your questions you need to answer two basic questions. How much money do you want to spend and how much efficiency in your antenna system are you willing to sacrifice? As a general rule, the more resonant bands you tie to one feed line lowers the efficiency of each band.

The VHF/UHF output is the easiest one to satisfy. You can build a dual band j-pole or groundplane for very little that will give satisfactory results. There are plans for them on the net. Or you can purchase a commercially made antenna like I did. After 40+ years of building my own, I decided to take the easy way out. I use a Diamond X-50A. They sell for around $100 and are factory assembled and tested.

The HF/6meter is a different story. 1.8 to 50 mhz is a very wide frequency spred. I do not know of any commercially made antennas specified to operate over this frequency range. B&W makes a T2FD that covers 1.8 to 30 mhz, but its performance is questionable. There are several muti-band verticals that cover 6 thru 20 meters and a couple that also include 40 meters, but they are expensive. If you have a tuner you can string up a 265" dipole and center feed it 450 ohm balanced line that will tune this range. But again, efficiency will be sacrificed.

Having fun is the name of the game. Experiment and see what works best for you.

73
Ken
KK4BH

Robert,

I assume "plane Jane" refers to the first model produced, the IC-706. I presently own a IC-706MK2G and previously a IC-706MK2. Never owned the original model. The low modulation plagued my MK2. It seemed the problem was the microphone, which had a round rubber diaphram over the microphone element. This diaphram was supposed to protect the element from moisture, but doing so de-sensitized it. You would have to turn the mic gain all the way up and talk loud just to get any decent modulation.

I found a mod posted on a newsgroup at that time, describing how to disassemble the mic and remove this diaphram. After performing this mod I received reports, from stations who knew me, of excellent modulation even with the gain turned lower. I am not aware of any circuitry mods to correct this problem.

I have only used a IC-SM20 desk mic on my MK2G, so don't know if this problem carried down to this model.

Robert, many of these radios were built and there's an abundance of info on them. Hope I was of help.

73
Ken
KK4BH

 

Jerry,

I too would not buy any radio equipment from somebody who smokes. Previously a smoker, I stopped about 25 years ago. When I'm around people who smoke it makes me think that I used to smell like that. Not a very pleasent thought.

One of my daughters, now grown and never smoked, dated a guy who did smoke. She would no sooner walk in the house after several hours on a date, our home reeked of smoke. Imagine a intricate piece of radio equipment exposed to several years of this. No thanks!

73
Ken
KK4BH

Brent,
I have read about many fan mods to the 706MK2G, ranging from making the fan run all the time to cycling it to a slower speed in receive. My question is this --- Why do it? I have owned one of these radios since new about 18 months. Always used as a base, it's powered by an Astron RS-35M and left on 24/7 for weeks at a time. Yes, it gets warm and the fan cycles on and off about every 15 to 30 minutes, depending on the ambient room temperature. When it's running it's only about 30 seconds. The radio does not seem to get what I consider overly warm. In addition to drawing air through the bottom of the radio there is a fiber filtered vent on the top cover next to the speaker that frequently cloggs with dust. I keep it clean with a small computer vacuum. If it aint broke, why fix it? Just my honest opinion Brent, and good luck.

73
Ken
KK4BH

Torgeir,

I find the 1.9 khz (FL223) filter to be quite effective on my 706MK2G. Having full size seperate 40m & 80m dipoles, many of the signals are very strong, 20 or more db over S9. The filter alone removes most of the QRM and a slight adjustment of the IF SHIFT usually gets rid of the stubborn ones. Of course there are some interfering signals, no matter what you do, will go completly away. The narrow filter also reduces receiver background noise making it quieter. Hope this helps.

73
Ken
KK4BH

Tom,

Coiling the legs of a dipole like a "slinky" will induce a inductance factor that depending how you feed the antenna will greatly effect its SWR. Feeding it with coax you would most likely will have a unusable SWR. Feeding it with open line you could tune it with a tuner but its effientcy might be quite poor due to the cancelling effects of the "coils". Anytime you shorten a antenna you reduce its performance, a "compromise".

It sounds to me you have a space limitation. I think you would be better off, if space allows, to get the antenna as high as possible and let the ends droop straight down, not toching the ground. You can also "zig-zag" the antenna wires but remember not to run the wires back on themselves (paralell) as this will cause a cancelling effect.

Gud luk es hve fun,
Ken
KK4BH

by WN3R on June 29, 2005  
"Invite the neighbors to your station and teach them about your hobby. The more they understand the less they will be inclined to be against you or it."

Good suggestion. Ignorrance can be a leading cause of problems between people. Most important, BE POLITE!. If any of them comment on the legality of your tower, just tell them you thoroughly investigated the necessary proceedures to obtain your permit and be happy to show them to them.  

"I'd also tell them you're planning a second much taller tower. Get them to focus on something worse."

Bad choice. If a "fire" is just starting the last thing you want to do is throw gasoline on it. Remember, you catch more flies with honey than with vinegar.

73
Ken
KK4BH

Frank,
I second Tom, KR4BD's advice. If the radio is still in warranty let them repair it. Attempting to perform any of the repairs yourself could leave you responsible for some expensive repair costs. I had a 706MK2 for several years and now own a 706MK2G for over a year without any problems. The radios are left on for almost 24/7.

73
Ken
KK4BH

Did you receive a owners manual with it? Some of the older MFJ manuals had a alignment section to them. You can download most of their manuals online. Also you will need a accurate reference meter to calibrate the power output. This also needs to be performed into a non-inductive 50 ohm load to accurately calibrate the forward and reflected power. Using your antenna for a load can add error to your calibration due to SWR fluctuations.

Finally, you can drop MFJ a email and tell them of your situation. While many hams "trash" MFJ, I have had very good luck with their products and service.

73 es good luck,
Ken
KK4BH

I believe the mike wiring for all the 706's is the same. The 2005 HRO catalog shows the SM20 desk & the HM103 hand mikes compatable with the 706 & 706MK2 series. I have a 706MK2G using the SM20 without any problem. Of course you have to use an adapter if the mike does not have a modular connector. You could also go to "mods.dk" and compare the scematic wiring of the 3 radios.

73
Ken
KK4BH

I chose a Diamond X50A and feel it was a excellant choice. Very well constructed and easy to install, the SWR measured well below 1.5:1 on both 144 & 440mhz. Performance is very good. I picked it up at HRO with 25' of 9913 coax and 2 PL259 connectors shipped to my door for about $120.

Have fun es 73
Ken
KK4BH

Jimmy,

By the way, the Icom OPC-589 Adapter is $35 from HRO.

Ken
KK4BH

Jimmy,
The adapter you're looking for is a OPC-589. When using the SM-20 mic with the 706 you will have to balance the gain settings of the radio and the microphone. I have found that comparing the SM-20 to the stock hand mic is like "night & day".

Have fun.
Ken
KK4BH

Paypal??? I signed up last May using a VISA debit card.

Ken
KK4BH

Have you checked the SWR across the band? I would check it at 144, 145, 146, 147 & 148mhz and find out where the best SWR reading is. If changing the feedpoint position doesn't bring the reading to a desirable level (say 1.5:1) and the SWR readings are sloped up or down one way across the band, you may have a dimensional error in the construction of the antenna. The only other factors would be the feedline or your SWR meter. I have built several j-poles and have had good luck getting the SWR down to 1.5:1 and 2.0:1 across the band.

73 es good luck
Ken
KK4BH