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Author Topic: Icom 7000, turbo tuner, antenna or something else?  (Read 644 times)
AB2MH
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« on: July 10, 2006, 09:27:53 PM »

So today I had the unfortunate luck of having an issue with my mobile HF system.  

I have an Icom 7000, tarheel II screwdriver antenna and the N2VZ turbo tuner to tie it all together.  I love how everything works.  I can change bands easily and safely without taking my attention off the road.

But today I have a problem.  I notice first of all that my 7000 is not putting out the full 100w, even into a dummy load.  It is putting out more like 75w on 20m.  The voltage going to the radio is a healthy 13.6-13.9 volts, so I don't think that is the problem.  I have 6AWG cable going to the radio so the power cable is adequately sized and can handle the load.  In fact I didn't have an issue before today.

The other problem is that the turbo tuner will not tune on 40m and 80m.  It used to do this flawlessly before, but now it will tune for a bit on 40m then go to "park" mode and it will just go to "park" when tuning on 80.  20 and up tunes just fine.

So what could be the problem?  I want to think the Turbo Tuner is the problem but the problem of reduced output at the radio is troublesome.  I have a suspicion that the radio may not be getting full voltage internally, probably a bad regulator or something?

I really doubt that RFI is suddenly getting into the turbo tuner.  It is supposed to be RFI bulletproof up to 1kw and I have taken great pains to make sure that RF is not getting in where it's not wanted. But yes, I know the problem definitely looks like RF is affecting the turbo tuner, but get this - the problem happens even when the radio is connected to a dummy load.

I have already emailed Bill N2VZ and I'll have to see what he says.  But I was wondering if anyone here had a similar problem, and if there were any known issues with the icom 7000.

Thanks Ryan AB2MH.
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AB2MH
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« Reply #1 on: July 11, 2006, 05:38:32 AM »

Further testing is leading me in the direction of RF getting in somewhere.  I can also get full output on 10m but not on the lower bands.  Hmmm...
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K0BG
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« Reply #2 on: July 11, 2006, 05:55:15 AM »

First of all Ryan, where are you measuring the DC voltage? Here's a suggestion. Measure it at the tuner port. A brand new Icom cable for the IC-7000 that I checked under load (13.8 volts from bench supply at 21 amps) measured 13.1. That's a 7/10 volt drop, and the output power was 85 watts. Also, recheck the power setting in the Quick Check mode.

Secondly, although the Turbo Tuner is one of the better units, it too is prone to RFI if things aren't properly grounded and bypassed. Any thing coming loose might have caused the problem. Coax connections included.

Lastly, connect the TT coax connection up to light bulb load as see how it acts. If it appears to work as it should, you have some more work to do looking for the problem. I'd bet it doesn't.

Alan, KØBG
www.k0bg.com
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AB2MH
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« Reply #3 on: July 11, 2006, 08:52:25 PM »

Did not have much time to check the output with a lightbulb,  but I checked the grounding, bonding etc. With coax disconnected from the tuner I am getting less than an ohm between the shield of the coax and the car's body, which tells me that it is well grounded.  

Tomorrow I check the voltages at the tuner.

I still have not heard back from Bill N2VZ yet.  I'll probably give him a call sometime tomorrow if I don't hear anything.

I will also try taking the radio out of the car and testing it in the shack and see if I get less than full output from the radio with a regulated 13.8V supply.  
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AB2MH
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« Reply #4 on: July 12, 2006, 04:51:13 PM »

Hooked up the 7000 today in the shack to a dummy load and watt meter.

I first did a CPU reset to return the radio to its factory state.

100W on 10m
~80w on 12m
~80w on 17m
~75w on 20m
~50w on 30m
~10w on 40m
~5w on 80m
the needle wouldn't even move on 160.

Same results for CW, SSB, FM.

40 and 80 were the two problem bands, btw.

I'm not into QRP, at least not while mobile, so the radio is going back to icom tomorrow morning.

TT appears to be fine as it works OK with my 746.

Thanks for your help, Alan.
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AB2MH
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« Reply #5 on: July 14, 2006, 04:54:52 AM »

I also found out something else about the turbo tuner -

It watches its RF input to determine if you've pressed "tune" twice so it can park the antenna.  In other words if it detects the "tune" signal, then afterwards detects no RF, it goes into park mode.  So if you're having issues where the tuner is immediately parking the antenna, it is very likely that your radio is not outputting anything.
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AB2MH
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« Reply #6 on: August 04, 2006, 09:42:33 AM »

Got the radio back today, reinstalled it and it works fine.

The finals were bad and Icom replaced them.
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