Quantar TX lock flickering

[WB4JGI]

I have quite a strange problem on my hands. I have a VHF range 1 exciter and PA deck programmed to 152.xxx and when the station powers on the TX Lock LED flickers/flashes about 250ms on and off. When I TX from the Station Control Module that LED flickers very fast about 75ms on and off. Mind you this is a "cold powerup" at below 45 degrees Farenheit.

I have found that this problem only happens when the station is turned on below 45 degrees Farenheit. I've powered the station off and using a heat gun, set to low power about a fott away, and blowing on the exciter module for about 30 seconds. Upon powering up the station the exciter locks and the PA full light comes on and the station is putting out the 60 watts it's supposed to. It seems to me that the TX VCO is out of whack, but without a service manual it's hard for me to make that determination for sure. I'm just curious to see if this can be repaired without sending it in. God only know what it costs to repair this module.

Any assistance is appreciated.

Thanks all and happy holidays.

[Bill_G]

Is this a service related problem, or out-of-curiosity problem? That is, is your customer's radio in a cold building and having intermittent xmit problems, or is this a personal radio that you use? A heat gun on low a foot away for 30 seconds aimed at an exciter module installed in a Quantar chassis shouldn't heat up more than the paint, but I have seen stranger things.

[WB4JGI]

This is service related as the station won't keyup until it gets above 40 degrees, at least from my testing that is what I have found thus far. This is my personal station and the transmitter room it will be in has no heater.

[Bill_G]

I would do all the basics first then. Remove every module, blow out the dust, clean the connectors, reseat the modules, and do the entire alignment procedure including reinitializing the ref osc if that option is available to you. Do it all at room temp. Then let the station chill overnight down to your known fail temp, and retest. Hopefully it is just a matter of maintenance. Quantars are so reliable, they are often neglected, and winter seems to bring out the worst in them. I've had more than my share of snowshoe trips with a SAR deputy to sites buried +100 inches that the state/city/county/fed techs could not reach by cat that were resolved by alignment.

[WB4JGI]

I was able to do a bit of tuning on the station today. I got to the part about tuning the TX VCO coils and after being put in the freezer for 15 minutes, to simulate cold site conditions, the VCO locked immediately upon power up. But no carrier on frequency was detected the service monitor only showed 60 watts out, which is what I have the station set for. But no frequency showed up on the service monitor as it normally would and it would also normally show about .07khz of audio while the station is keyed locally but it showed 0.

But if I let the station sit for about 5 minutes or so and I key it either locally or with a radio the station modulates/repeats audio and frequency is displayed on the monitor and shows it's -.0016 off frequency, but that's as close to 0 as I can get it which is good enough for me.

I'm to the point now where I need some sort of card extender to go further with this. Do they make the card extenders for the Quantar, similar to the old Micor extenders or am I out of luck on that? Also would anyone have the part number for the extender if one is made?

Thanks

[Bill_G]

So, after freezing the exciter module, you had tx lock and power out, but couldn't see it on the service monitor for five minutes. Do you have a spectrum analyzer to see what freq it was on? I do not know if there are extender cards for Quantar modules. Definitely would be handy for your problem. Unfortunately, most of us mail it into Moto for service at this point. You are in unknown territory.

[WB4JGI]

Yes the service monitor I'm using, which is an IFR COM-120A, has a spectrum analyzer built in but I don't know how to make it scan so I set the scope for 1Mhz bandwidth and manually increased the frequency as needed I found a small spike at 148.903mhz it was around 100-110 dbm and would appear and disappear as I would TX from the SCM.

Do you know how much it is for Moto to look at this? I hope the flat rate isn't to much for this.

I was able to track down the part number TLD9831F for a new exciter board which is $412 my cost. I would almost be inclined to get that, but I'm not sure if the firmware chip is included with that or I just switch out the firmware.

[The Pager Geek]

I was able to track down the part number TLD9831F for a new exciter board which is $412 my cost. I would almost be inclined to get that, but I'm not sure if the firmware chip is included with that or I just switch out the firmware.

How old is the module / version? Last release for exciter is 2005 (that I know of.)

tpg

[WB4JGI]

In my station all the modules are up in the 20.xx.xx range and it seems to work well. My exiter model revision is the A revision instead of the current F revision. Is the quantar still a current station, or have they just not released one since 2005?

[The Pager Geek]

In my station all the modules are up in the 20.xx.xx range and it seems to work well. My exiter model revision is the A revision instead of the current F revision. Is the quantar still a current station, or have they just not released one since 2005?

I meant that the firmware for the exciter hasn't been changed or updated since 2005. Stable is good.

I'll see if I can dig up the FW part number for you later in case you have to buy it sep.

tpg

[WB4JGI]

ok that was gonna be my next question is if the firmware came with the TLD9831 part. Where is the firmware stored in this station? In all the modules seperatly or is it all in the SCM module and gets sent out everytime the station is on? Feels like a dumb question to ask but I've never known where it's stored in this station.

[The Pager Geek]

ok that was gonna be my next question is if the firmware came with the TLD9831 part. Where is the firmware stored in this station? In all the modules seperatly or is it all in the SCM module and gets sent out everytime the station is on? Feels like a dumb question to ask but I've never known where it's stored in this station.

Exciter FW is on the exciter
Wireline FW is on the wireline card (if present)

Any other FW is located on the SCM

tpg

[WB4JGI]

oh ok makes sense now.

[Ali Abbassi]

You can narrow down this by following:
While the TX LED is flickering , go to Service section of the RSS and select F4 for status report , and see if you can find anything related ,also while in service
mode go to Diagnostics (F5) and select F4 for Exciter, select all the fields for cold and warm start ,also do the HSO/UHSO (F8) for all the cold and warm start ,

[WB4JGI]

I noticed while I was in service mode that the TX lock indicator would go from locked to unlocked rapidly it seemed to match the exciter TX Lock LED. I've got a replacement exciter on the way for testing I'll post what I find with both the old and new modules.