Ic-706mk11 rf out put problem
I have an ic-706mk11 rf output on 160 m 2 watts, 75/80m 10 watts, 40m 35 watts,30m 65 watts and 20
thru 6m 105 watts. this test done with the same coax rf watt meter and dummy load. Can anyone point
me in the direction to correct this problem. I don't have a service manual only the operator's.All measurements taken mid band.
Any and all help will be appreciated.
The service manual is available here:
Hope this helps.
Maybe a band pass filter problem? Looks like maybe a higher frequency (20M to 6M) band pass filter is being turned on when you are at 30 meters and below, and affecting the output power. Might put an ammeter in line with the power cord and see if it's showing similar amp draw when transmitting on all the bands, or if the current draw follows the lower output.
Good luck! 73,
Not likin' that too much, because the RF output stage will likely go into Foldback Protection when the wrong output filters are involved, protecting the output transistors from destruction by limiting the Current draw to them.
Originally Posted by KB8YVC
I prefer locating the output coax from the PA, disconnecting the tiny connector there and connecting dummy load and wattmeter directly to the PA to see if all bands are actually making full power when terminated in a 50 ohm load. If they are, suspect the output filtering section. My next move is usually to reattach the PA to the filters and then try to transmit that way, again into dummy load and wattmeter, and actually TAP on each relay top with a spudging tool while watching the output (CW mode, if you please). Often, the tapping can isolate a relay with stuck contacts. Note that the pcB HOLD DOWN SCREWS often get loose or corroded and may be used as ground points for boards, always give each and every board holddown screw a quick tighten, which often cures these kind of problems without having to purchase a single new component!
If no joy there, then I have to get out the schematic, isolate the relays involved with each suspect band and use the scope or DMM to see if each is powered (and that those not involved are NOT powered at the time) in an effort to find out what's really happening there.
thanks to all for you help. still been unable to locate the relay that is causing the problem the service maual
helped to get it down to the board but 16 relays on the board and they are sealed can't seem
to be able to check them without keying the rig the xyl finally got mad and won't help me now
so i boxed it up and sent it to WA.
Update on this problem:
Sent the radio to Contek Washington he checked it out could not find any problem with the rig.
Got it back from the shop still had the same problem i checked all coax jumpers, grounds and every thing
else i could think about. Finally borrowed another pwr. meter from a friend and it shows 100 watts on
Doing little research i find out the meter i was using was only good from 25 to 30 mhz.
I seemed to have had a bad case of the dummies. The meter was a Workman p 5000 their
is no model nbr. on it but beware it won't work for general ham use.
Thanks to all who offered their help it is appreciated.
Meter was probably designed for sale to the 11 meter CB market...
Hi Rodger, yup a humbling moment, hate it when that happens. You can also use this as a lesson on the proper use of test equipment and to select the proper unit for your tests. Knowing a bit more about your IC-706MKII would also narrowed it down for you. If the relative power out on the rigs meter indicates 100W but your external wattmeter reads 2W something is terribly wrong. Now, the circuits that would be used to cutback the power during a high SWR event are after the filters in the final. This would mean if a filter was the problem then the IC-706 would not get the information to cut the power back and it would still try putting out full power. This would not be read on the relative power display on the rig. So, if you have a reading on the relative power display and the rig is not cutting back there is most likely nothing wrong with your filtering.
That leaves you with the problem of having two wattmeters that do not agree. Which one is right? Considering the intended use of the Workman P5000 I would have zeroed in on that very quickly. What would have been a benefit to all those that tried to help is to have known what you were using to determine the power problem. This isn't just in the posting but others that leave information out. That can be very important and would have saved you and everybody else time and in your case some money (if you had to pay for shipping and the checkout).
It is nice to get some one else to check things out for you and that alone helped eliminate the possibilities. It would have been better to get a nearby amateur to check it out. I know sometimes that it's hard to find someone near you but it's always worth the effort.
Have fun and I'm glad nothing was wrong with your rig.
One of the things that perplexes me is that when I was a Novice an Elmer was easy to find. Now, with a lot more amateurs, they're rare and difficult to find. Anybody know why?
Last edited by KO6WB; 08-08-2012 at 10:36 PM.