Have a UHF 32CH 16pin Maxtrac being used as a tone remote radio. Upon inspection on an RF meter, when it first keys it does 25w, then will, occasionally, drop down to around 15. Or sometimes it will key up on 15w first and just hover around there. Oddly enough, I believe this is a D44 45w radio?
Is this signifying a bad PA?
Maxtrac power drop??
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Re: Maxtrac power drop??
You would probably do your self a favor by trying some homework first. Have you taken a volt meter and looked at
the DC voltage going to the radio? Measure it at the radio in receive and in transmit. Make sure your power
supply is able to hold voltage under the current of TX. You might even have a dirty or loose power connection.
Other than that, your going to have to get into the guts of the radio and start looking at various areas that
could cause the problem you are talking about. Kind of hard to remotely trouble shoot a problem without
having some info to go by.
Jim
the DC voltage going to the radio? Measure it at the radio in receive and in transmit. Make sure your power
supply is able to hold voltage under the current of TX. You might even have a dirty or loose power connection.
Other than that, your going to have to get into the guts of the radio and start looking at various areas that
could cause the problem you are talking about. Kind of hard to remotely trouble shoot a problem without
having some info to go by.
Jim
Rayjk110 wrote:Have a UHF 32CH 16pin Maxtrac being used as a tone remote radio. Upon inspection on an RF meter, when it first keys it does 25w, then will, occasionally, drop down to around 15. Or sometimes it will key up on 15w first and just hover around there. Oddly enough, I believe this is a D44 45w radio?
Is this signifying a bad PA?
-
kc7gr
- Posts: 1031
- Joined: Wed Mar 13, 2002 4:00 pm
- What radios do you own?: Motorola, Icom, Sunair (HF).
Re: Maxtrac power drop??
You don't mention if the radio has been converted to amateur frequencies. If it has, this symptom is fairly common, due to the fact that the frequency tables in the radio's firmware (specifically, the ones that tell the D/A converter how much drive to hit the PA with) were never designed to accommodate hamateur freqs.
Definitely check the DC power first, as others have pointed out. If this radio has been converted, and the DC power is OK, you will probably need to apply a manual power control modification. This involves cutting one trace, and installing three fixed resistors and one trimpot. Following that, of course, you need to tweak the trimmer for the appropriate power level.
Happy testing.
Definitely check the DC power first, as others have pointed out. If this radio has been converted, and the DC power is OK, you will probably need to apply a manual power control modification. This involves cutting one trace, and installing three fixed resistors and one trimpot. Following that, of course, you need to tweak the trimmer for the appropriate power level.
Happy testing.
Bruce Lane, KC7GR
"Raf tras spintern. Raf tras spoit."
Re: Maxtrac power drop??
Yes it is on ham, it is acting as a link to the TR on 448.150. I figured 448.x isn't too far out of band, but if the tables aren't present, then that makes sense I suppose.
I'll try measuring RF PO on 464.55 into a dummy load when I get home later and see if the power is proper there.
I'll try measuring RF PO on 464.55 into a dummy load when I get home later and see if the power is proper there.
Re: Maxtrac power drop??
A UHF D44 is a 40 watt unit, Depending on split (403-430 OR 440-470) it should tune in it's respective range under RSS control.
After checking what the others mentioned, also check the mini-U connector, they get loose on the center pin, you can bend them gently.
Also if the radio was "upgraded", a full alignment may not have been done! (F2 service, replace board, logic board). Symptoms include dropping off in power in descreet steps!
After checking what the others mentioned, also check the mini-U connector, they get loose on the center pin, you can bend them gently.
Also if the radio was "upgraded", a full alignment may not have been done! (F2 service, replace board, logic board). Symptoms include dropping off in power in descreet steps!
Re: Maxtrac power drop??
You can tell if the output power is being rolled back by the power control circuit by measuring power control voltage, especially if you can catch the radio in the act of changing from 25 to 15 watts. Also, compare the amount of DC current draw on the power supply for a given output power at different frequencies in the operating range of the radio.