[chirp_devel] VX-7r: power levels for 1.25m band
The Yaesu VX-7r supports L1 and L2 power settings for the 1.25m, but for some reason Chirp will not accept L2 for that band. Looking at the code in chirp/vx7.py I see where the check is made and L2 should be accepted. I cannot figure out why this check refuses to accept L2. The workaround is to manually reset the power level to L2 and re-save. Has anyone else tried to fix this?
Slightly related to this problem, one can modify the VX-7r to boost the transmit power for the 1.25m band. This is done by entering the factory setup mode. Looking again at chirp/vx7.py, I see statements that look like this: chirp_common.PowerLevel("L2", watts=0.30) What does that "watts=0.30" mean for the rest of Chirp? Will that interfere with the power mod mentioned above?
The Yaesu VX-7r supports L1 and L2 power settings for the 1.25m, but for some reason Chirp will not accept L2 for that band. Looking at the code in chirp/vx7.py I see where the check is made and L2 should be accepted. I cannot figure out why this check refuses to accept L2. The workaround is to manually reset the power level to L2 and re-save. Has anyone else tried to fix this?
Nope, I had it in the queue. Now that you asked, I looked and I see the problem. Skipping down:
Looking again at chirp/vx7.py, I see statements that look like this: chirp_common.PowerLevel("L2", watts=0.30) What does that "watts=0.30" mean for the rest of Chirp? Will that interfere with the power mod mentioned above?
The reason we tie an actual signal level (in watts or dBm) to a PowerLevel is so that during import or copy/paste, we can attempt to select a similar power level on an incompatible radio based on the available power levels. The problem here is that the VX7 driver declares to the outside world the main list of power levels. That means that when the user selects L2, it passes the 1-watt L2 power level into the validate operation, and the driver balks at the request for a power level not supported on 220.
There are two options here:
1. You can declare the 220 L2 to be the same power as that of the main list and then the comparison will succeed. The potential for error here is very minor and I think intentionally misrepresenting the 220 power levels are unlikely to cause anyone heartache 2. You could change the check to something like this:
if str(mem.power) not in ["L1", "L2"]: # Fail
Effectively changing the 220 comparison from absolute power level to by name.
Slightly related to this problem, one can modify the VX-7r to boost the transmit power for the 1.25m band. This is done by entering the factory setup mode.
Interesting. Got a link?
On Wed, 9 May 2012, Dan Smith wrote:
The Yaesu VX-7r supports L1 and L2 power settings for the 1.25m, but for some reason Chirp will not accept L2 for that band. Looking at the code in chirp/vx7.py I see where the check is made and L2 should be accepted. I cannot figure out why this check refuses to accept L2. The workaround is to manually reset the power level to L2 and re-save. Has anyone else tried to fix this?
Nope, I had it in the queue. Now that you asked, I looked and I see the problem. Skipping down:
Looking again at chirp/vx7.py, I see statements that look like this: chirp_common.PowerLevel("L2", watts=0.30) What does that "watts=0.30" mean for the rest of Chirp? Will that interfere with the power mod mentioned above?
The reason we tie an actual signal level (in watts or dBm) to a PowerLevel is so that during import or copy/paste, we can attempt to select a similar power level on an incompatible radio based on the available power levels. The problem here is that the VX7 driver declares to the outside world the main list of power levels. That means that when the user selects L2, it passes the 1-watt L2 power level into the validate operation, and the driver balks at the request for a power level not supported on 220.
There are two options here:
- You can declare the 220 L2 to be the same power as that of the main
list and then the comparison will succeed. The potential for error here is very minor and I think intentionally misrepresenting the 220 power levels are unlikely to cause anyone heartache 2. You could change the check to something like this:
if str(mem.power) not in ["L1", "L2"]: # Fail
Effectively changing the 220 comparison from absolute power level to by name.
I think this one would be ideal. I'll work on a patch and post it later tonight.
Slightly related to this problem, one can modify the VX-7r to boost the transmit power for the 1.25m band. This is done by entering the factory setup mode.
Interesting. Got a link?
http://wa6plc.info/VX7_220_TX_power.pdf
It's a distillation of the service manual, which is available here: http://www.repeater-builder.com/yaesu-vertex-standard/pdfs/yaesu-vx-7r-techn...
I haven't applied it yet because I want to acquire a wattmeter so I'm not flying blind. Do you have any idea why Yaesu limited 1.25m to such low power?
I haven't applied it yet because I want to acquire a wattmeter so I'm not flying blind. Do you have any idea why Yaesu limited 1.25m to such low power?
Yeah, because there isn't a dedicated 220 PA in there, and so they're just driving the regular VHF PA real hard off to one side. The VX8 does the same thing, but defaults to letting you run more power. An optimist might say that the RF bits between the two radios are similar and thus it's okay on the VX7. However, it's already kinda working out of spec and driving it harder is asking for trouble, IMHO.
On Wed, 9 May 2012, Dan Smith wrote:
I haven't applied it yet because I want to acquire a wattmeter so I'm not flying blind. Do you have any idea why Yaesu limited 1.25m to such low power?
Yeah, because there isn't a dedicated 220 PA in there, and so they're just driving the regular VHF PA real hard off to one side. The VX8 does the same thing, but defaults to letting you run more power. An optimist might say that the RF bits between the two radios are similar and thus it's okay on the VX7. However, it's already kinda working out of spec and driving it harder is asking for trouble, IMHO.
The consensus seems to be that 1 watt is the ideal level to push it to. What could happen if I push it any more?
The consensus seems to be that 1 watt is the ideal level to push it to. What could happen if I push it any more?
I imagine that the simplest answer is that you're turning up the gain to try to get more power out, and thus closer to the potential thermal overload point. I expect that any overhead they have in the thermal domain is not utilized because they wouldn't pass FCC type certification due to distortion or other noise products. Obviously if the hardware could do it without burning up or distorting the output, they would have set that as the default. Since their only competitor on 220 is a full five-watt handheld from Kenwood, I can't imagine they limited the output for anything other than a Good Reason(tm) :)
On Wed, 9 May 2012, Dan Smith wrote:
The consensus seems to be that 1 watt is the ideal level to push it to. What could happen if I push it any more?
I imagine that the simplest answer is that you're turning up the gain to try to get more power out, and thus closer to the potential thermal overload point. I expect that any overhead they have in the thermal domain is not utilized because they wouldn't pass FCC type certification due to distortion or other noise products. Obviously if the hardware could do it without burning up or distorting the output, they would have set that as the default. Since their only competitor on 220 is a full five-watt handheld from Kenwood, I can't imagine they limited the output for anything other than a Good Reason(tm) :)
I guess the solution then is to get a Kenwood. But I can't afford that yet and I'm starting to have a thing for Yaesu stuff. I wish they'd be more serious about 220.
I guess the solution then is to get a Kenwood. But I can't afford that yet and I'm starting to have a thing for Yaesu stuff. I wish they'd be more serious about 220.
Well, most of them aren't serious about 220 because it's not a ham band in most of the rest of the world, thus committing resources to it makes it useful only in the US. Yaesu is driving their VHF PA hard so that they can get something out of it, but only because it's "free". I doubt the other manufacturers would be willing to cut corners like that, which is why you don't see anyone else doing it.
participants (2)
-
Dan Smith -
David Griffith