moronic service question (within rss)

[Aces-Warehouse]

I am wondering about some options....

I have a gp300 and I can modify the TX power from within RSS. I do not have a service manual or meters and I am very curious of what these should be. I want maximum power / performance out of my GP300 and appreciate any information. I already know this much...

"Do not attempt anything without proper knowledge and equipment".

So my questions are:

1. What are the default settings?
2. What are the optimal settings you have found?
3. What settings do you recommend changing to make my gp300 work at FULL capabilities?

Thanks in advance,
Ace

[kc7gr]

Darn editor... Try again...

[kc7gr]

I am wondering about some options....

I have a gp300 and I can modify the TX power from within RSS. I do not have a service manual or meters and I am very curious of what these should be. I want maximum power / performance out of my GP300 and appreciate any information. I already know this much...

"Do not attempt anything without proper knowledge and equipment".

So my questions are:

1. What are the default settings?
2. What are the optimal settings you have found?
3. What settings do you recommend changing to make my gp300 work at FULL capabilities?

The problem you face is that NO two radios are ever exactly alike in which settings will produce a given level of performance.

In short: If you don't have a service monitor, or some other reliable and accurate way to measure power output, modulation, and frequency error, don't attempt to do the adjustments.

Another thing to keep in mind is that firewalling the power output will serve only to drain the battery that much quicker, and wear down the final output device(s) faster, at a very minimal gain in performance.

If the radio has already been factory-aligned, then it is already set at the optimum balance of output and current drain.

[Wowbagger]

IF you are doing APCO-25 Phase II or APCO-25 LSM, and you rail the power, you will make the RF amp be non-linear. This is a BAD thing when you are doing QPSK (which is what Phase II and LSM are).

For example, here's what a good P25 LSM signal should look like:


Look at the I/Q plot in the lower right of the screen - see how the red trajectory lines are going through the middle and outside the "unit circle" the decision points (white dots) are on?

Now, look at what happens when you drive an amp into compression:


See how the trajectory is compressed to be on the unit circle - that's bad. You can see how the spectrum has regrown outwards - you are spattering out of band.

You will see this to a lesser extent even with normal Smartnet or C4FM APCO-25, but it REALLY gets bad for QPSK.

Short answer: unless you have AT A MINIMUM a spectrum analyzer and power meter, don't mess with your settings.

[Aces-Warehouse]

Thank you. Now, how much would you guys charge to have this done? I want it to operate at its BEST capabilities.

[Wowbagger]

Thank you. Now, how much would you guys charge to have this done? I want it to operate at its BEST capabilities.

If you are addressing me - we don't calibrate radios. We make the equipment to calibrate the radios. The 2975 I used to generate those examples would run about $30,000 with the options needed to do what I did (base unit $21K, P25 Phase 2 $2K, Phase 2 advanced test $6.8K - numbers are VERY rough, call for quote, yadda yadda)

There are a few Batboarders who have Aeroflex gear who might be willing to tune your radio for you.

[kc7gr]

Thank you. Now, how much would you guys charge to have this done? I want it to operate at its BEST capabilities.

If you're talking about a conventional radio, I can do the alignment and checkout for you. So can Monty.

My rate is $40/hour. Assuming nothing is really wrong with the radio, and you just want programming, alignment, and checkout, you're looking at between $20-$40 plus shipping.

What I would need would be the radio (obviously), your amateur, commercial, or GMRS callsign, and a list of frequencies/PL codes, etc. that you want programmed into it.

PM me if you want to set things up. Certainly feel free to shop around as well, and compare rates.

[Aces-Warehouse]

Negative, I have it programmed to my freq's. I have a RIB. I am only looking for alignment and power peak / tuning.

Ace

[kc7gr]

Negative, I have it programmed to my freq's. I have a RIB. I am only looking for alignment and power peak / tuning.

Ace

That being the case, $20 plus shipping will take care of it nicely.

I'm here if you need me.

[jbxx]

I've got to clean the drool off my computer
now, WOW!
J.B. AD6WX

[thehead7]

Ace,

It sounds like Bruce has a good deal on aligning your radio. You're surely not going to get that price from a service shop, I'm sure.

Just thought I'd stick my nose in where it doesn't belong...

73
John

[Will]

If the radio is not all screwed up by someone forcing a wrong code plug into it, the alignment AND Calibration on all the sub-cal points usally costs $15 to $50 plus return shipping. It takes about 1.2 hrs to do it correctly.
This is the BatBoard member prices, and I am open to neg.
If you have several radios, the price would be a little less, just one shipping box to pack!!

[Aces-Warehouse]

Sounds like a really great price. The radio is in PERFECT condition and I just want the TX / RX / Wattage to its BEST/Maximum Performance. I will be PM'ing soon about doing this to my radio. Thanks,

Ace

[Triping]

The gp300 series of radio power spec is 4w max

The radio will operate above this level the norm i find is around 4.3-4.5

i have seen one at 6w but it didnt last very long. Lol

[Wowbagger]

The gp300 series of radio power spec is 4w max

The radio will operate above this level the norm i find is around 4.3-4.5

I always love it when people obsess over power like this:

4 watts is 36.0 dBm
4.5 watts is 36.5 dBm
6 watts is 37.8 dBm

Typically 1 S-unit is 6 dB.
Doubling distance increases free-space path loss 6 dB.

So the difference between 4 watts and 6 watts is 1.8 dB - unnoticable on an S meter, and trivial for free-space range improvement.

[Will]

Wowbagger's math is correct, little noticable improvement.

There are several other points that will make the radio "talk out" better. A thourgh alignment AND compensation is needed first. There are more efficiant antennas that will also help a little.

Anyway much more than 4 watts into a good antenna will fry your eyes and maybe your brain, not to mention the poor battery on the radio and the overheated PA block in the radio that costs $100 to replace!