Novice question...
I have a bird wattmeter and considering buying a freq. counter.
1. Can I tune the radio with these 2 items or do I have to have a service monitor? (just for personal use, not business).
2. In RSS, there are multiple points in the tuning data section...soft pots..16 in some screens) to tune. What do these points represent?
3. If they represent a range of frequencies to tune to, what frequencies do they represent?
I'm using a UHF (438-470) radio, 25 watts.
thanks. pete
GM300 tuning
Moderator: Queue Moderator
Hi:
Tunning a Maxtrac / Radius is pretty stright
foward so long as you add the folloing equipment.
1. Since you have a Bird Wattmeter, if its one with a built in Dummy Load, you would be
A-OK, otherwise, you should find a suitable
50 Watt Dummy Load capable of working up to
1000 Mhz.
a) I would make some jumper cables with RG-142B/U for all your testing purposes. Or RG-223 is a good choice too
2. Most Frequency counters will get you " Close" but a good service Monitor is generally required. I would not make any changes in frequency ( period ) unless it has been tampered with.
3. A good Digital Voltmeter would be usefull
too, as one needs to measure pin 1 when going
through the entire transmitt alighnment proceedure. That voltage controls the VCO Compensating values, and is like 9.67 VDC
4. There is a More " Detailed" alighnment when / if the raido has been compromised, and
all the " pre-programmed " transmitter freqs
are already availible when adjusting the " Softpot" values. If I recall correctly there
are 20 Steps for the Power Range, and 20 for
the Tx Dev range.
5. I would not recommend changing any of the
" Dev" soft pot values unless again you have a Service Monitor and Scope. That is use to
make the radio sound well. It too has to be adjusted over the entire operating range.
These values placed to high or to low, will make the transmitter sound very poor
If you look at the Service Alignment Window you should get a idea of what the Steps 1-8
are all about.
Monty
Tunning a Maxtrac / Radius is pretty stright
foward so long as you add the folloing equipment.
1. Since you have a Bird Wattmeter, if its one with a built in Dummy Load, you would be
A-OK, otherwise, you should find a suitable
50 Watt Dummy Load capable of working up to
1000 Mhz.
a) I would make some jumper cables with RG-142B/U for all your testing purposes. Or RG-223 is a good choice too
2. Most Frequency counters will get you " Close" but a good service Monitor is generally required. I would not make any changes in frequency ( period ) unless it has been tampered with.
3. A good Digital Voltmeter would be usefull
too, as one needs to measure pin 1 when going
through the entire transmitt alighnment proceedure. That voltage controls the VCO Compensating values, and is like 9.67 VDC
4. There is a More " Detailed" alighnment when / if the raido has been compromised, and
all the " pre-programmed " transmitter freqs
are already availible when adjusting the " Softpot" values. If I recall correctly there
are 20 Steps for the Power Range, and 20 for
the Tx Dev range.
5. I would not recommend changing any of the
" Dev" soft pot values unless again you have a Service Monitor and Scope. That is use to
make the radio sound well. It too has to be adjusted over the entire operating range.
These values placed to high or to low, will make the transmitter sound very poor
If you look at the Service Alignment Window you should get a idea of what the Steps 1-8
are all about.
Monty
1. Can you tell me where I find pin 1 to measure voltage?
2. Is it the tx deviation settings that affect both tx and rx frequency calibration or is it the freq. warp setting (scale of 189 I believe) that does this?
The key problem is not tx power...these setting seem fine, but that when I receive voices are not clear, as though the radio is just a few KHz off freq.
thanks.
pete
2. Is it the tx deviation settings that affect both tx and rx frequency calibration or is it the freq. warp setting (scale of 189 I believe) that does this?
The key problem is not tx power...these setting seem fine, but that when I receive voices are not clear, as though the radio is just a few KHz off freq.
thanks.
pete
1. Can you tell me where I find pin 1 to measure voltage?
========================================
Pin 1 is one of the pins on the Logic/Interface 14 Pin connector in the
center of the board. One is marked pin 1
the other send is pin 14.
========================================
2. Is it the tx deviation settings that affect both tx and rx frequency calibration or is it the freq. warp setting (scale of 189 I believe) that does this?
========================================
The soft pot values " ONLY" effect receive
with the ONLY exception is the VCO, and that
is a very sensitive ajustment, and is Step
1 of the Alighnment. The DC Volatge measurement is critical, and the XTAL information is under the Shield Cover and is located on the Crystal, and the board number is on a small white strip. All of those numbers MUST be entered in correctly before proceeding with the major alaighnemnt.
In general, there is NO Such " Dev" alighnment for Receive. That is a Transmit
acronym
=========================================
The key problem is not tx power...these setting seem fine, but that when I receive voices are not clear, as though the radio is just a few KHz off freq.
==========================================
I think I have addressed this issue on more
than one occasion. If the TRANSMITT is right
on freq, then it would generally follow the RECIEvER should be right on freq as well.
Again, there are 2 types of GM300's, one is a 12.5Khz verison, the other is a 20 Khz version. If anyone has made any changes to the SMC componets, then you could expect a problem.
You might be fighting a bad speaker, or a
overloaded Audio problem as well. GM300's should sound Crystal Clear if everythng is working OK. ( Even at high levels ) You might
try a External Speaker and see if that improves the performance
MS
========================================
Pin 1 is one of the pins on the Logic/Interface 14 Pin connector in the
center of the board. One is marked pin 1
the other send is pin 14.
========================================
2. Is it the tx deviation settings that affect both tx and rx frequency calibration or is it the freq. warp setting (scale of 189 I believe) that does this?
========================================
The soft pot values " ONLY" effect receive
with the ONLY exception is the VCO, and that
is a very sensitive ajustment, and is Step
1 of the Alighnment. The DC Volatge measurement is critical, and the XTAL information is under the Shield Cover and is located on the Crystal, and the board number is on a small white strip. All of those numbers MUST be entered in correctly before proceeding with the major alaighnemnt.
In general, there is NO Such " Dev" alighnment for Receive. That is a Transmit
acronym
=========================================
The key problem is not tx power...these setting seem fine, but that when I receive voices are not clear, as though the radio is just a few KHz off freq.
==========================================
I think I have addressed this issue on more
than one occasion. If the TRANSMITT is right
on freq, then it would generally follow the RECIEvER should be right on freq as well.
Again, there are 2 types of GM300's, one is a 12.5Khz verison, the other is a 20 Khz version. If anyone has made any changes to the SMC componets, then you could expect a problem.
You might be fighting a bad speaker, or a
overloaded Audio problem as well. GM300's should sound Crystal Clear if everythng is working OK. ( Even at high levels ) You might
try a External Speaker and see if that improves the performance
MS