SteveShannon

Most modern radios can withstand an SWR well over 2.0:1 without damage. You can calculate the SWR at the antenna based on the losses you have calculated. Your SWR meter calculated 1.8:1 with the lossy cable, but that doesn’t include the losses for both forward power and reflected power. You calculated that 63% of the power is attenuated. I’m going to use 100 watts as the RF output just to make the calculations easier. With a 50 watts transmitter the values would be half. Your radio transmits 100 watts. You calculated 63% loss so 37 watts arrives at the antenna. So, this is why the measurement location matters. At the radio Forward Power is 100 watts and by the time it gets to the antenna Forward Power has been attenuated down to 37 watts. Due to an impedance mismatch some portion of the Forward Power reflects from the feedpoint and heads back towards the radio. That’s the Reflected Power. Again there’s a 63% loss before it arrives at the radio. Loss is loss for both Forward and Reflected power. Here’s an interesting article about SWR that correlates reflected power percentage to SWR in a table: https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf You measured an SWR of 1.8:1 (I assumed at the radio). That correlates to 8.2% reflected power. So, at your hypothetical radio, when transmitting 100 watts forward, 100 watts was seen as the Forward Power and 8.2 watts was seen as the Reflected Power and an SWR of 1.8 was calculated from those two values. But we know that 8.2 watts is the Reflected Power measurement after losing 63%, so 8.2 watts is really 37% of the actual Reflected Power (call that RP). As an equation 8.2 = 0.37 * RP. Rearranging, RP = 8.2/0.37. Solving, RP is 22.16 watts actually reflected at the feedpoint. But only 37 watts even made it to the feedpoint. So an accurate calculation of SWR at the feedpoint would be based on the Forward Power of 37 watts and Reflected Power of 22.16 watts. Again looking at the table in the ARRL article, the reflected power percentage is 22.16/37 or 59.9% and that calculates to an SWR of 7.85:1 (I used the online SWR calculator at https://www.aareff.com/en/calculating-swr/?srsltid=AfmBOoqd-GzPr7AeD9xpbmFecxHoSzzTGyKbeLlR00b78uweI9rYUxED) That doesn’t seem right to me if you’re using an antenna tuned for GMRS frequencies. Please check my math.

So the actual SWR of the antenna is almost certainly already higher than 1.8. No, I wouldn’t recommend not upgrading the coax. Lossy coax simply hides high SWR. The “right” thing to do depends on your resources. I would measure the SWR of the antenna right at the antenna feedpoint and adjust the antenna (tune it) until it’s as close to 1.0:1 as possible at the frequency you intend to transmit most often. I’ll have to go back and see what antenna you’re using and whether it’s one that can be tuned. Then, your reflected power will be reduced to the minimum and the attenuation of reflected power will have no effect on the apparent SWR.

I’ll correct my explanation to emphasize that the SWR is not actually going up, your measurement of reflected power is becoming more accurate. As a result the SWR value calculated at your radio will become higher, but in reality it has been the actual SWR hasn’t changed. You’re just seeing a more nearly accurate calculation. In other words, your SWR is higher than what you’re seeing and changing to the better cable will reveal that.

One thing to be aware of is that SWR will appear to go up, possibly by quite a bit. Here’s why: SWR is calculated using forward transmitted power and reflected power. At your radio the forward transmitted power is the maximum. Attenuation in your cable reduces it as it travels along the cable until it finally arrives at the antenna. There, any mismatch in impedance causes a portion of the power to be reflected back towards your radio. Again, attenuation robs power from the reflected power as it travels back towards your antenna. Your radio or a SWR/wattmeter measures the forward and reflected power wherever it’s inserted into the feedline. So, any power measurement done at the radio will measure the lowest possible reflected power and utmost forward power, which results in a calculation of SWR that’s not accurate. Let me emphasize that the actual SWR of the antenna doesn’t change, but because forward and reflected power are being measured at the radio, the calculated value of SWR is incorrect. Replacing the lossy 7 mm cable with less lossy 10 mm cable will result in less attenuation both ways which will result in a higher (but more nearly accurate) calculation of SWR. Of course the most accurate place to measure power is right at the feedpoint of the antenna, where the actual forward power delivered to the antenna and the actual power reflected by the antenna can be measured most accurately, but it’s almost always inconvenient to do so.

Have you ever received anything on the RA-87? There are only four reasons your RA87 wouldn’t receive from your HT and MXT500: wrong tone, desense, wrong frequency, or broken receiver. You undid setting Tone Mode to Tone when you set the RX Tone to 123.00. Set Tone Mode to Tone and leave the RX tone clear. Setting the RX tone to something is the same as setting TSQL and filters your incoming signals. Leaving your RX tone clear and setting Tone Mode to Tone tells your radio not to filter on tones but to allow everything through.Red redemption. When you’re troubleshooting reception problems you want to start by let everything in. Setting Tone Mode to Tone tells your radio to send a tone on transmit, but to let everything through on receive. Most times when someone cannot hear transmissions from another transmitter it’s because they have the wrong tone set for RX. Another common reason not to receive from another radio is because you’re too close to the transmitting radio and your receiver is desensing. Make sure your transmitting radio and receiving radio have some distance between them. Finally, if you’re not too close and you’re not filtering on tones and you still don’t receive things on your RA-87 maybe the RA-87 doesn’t receive. Have you ever received anything on the RA-87?

Change to Tone instead of TSQL.

Swapping in better coax certainly won’t hurt. I agree that a 63% power loss is substantial. What’s the projected power loss after swapping?

The db20g is not accessible through Chirp.

No

Get rid of your receive tone.

Don’t be a smratass.

For UF7 choose lmr240. For uf10 choose lmr400. That’s not exact, but it’s very close.

Good to know. Rich has been on the receiving end of hacking lately.

So will rebuilding the site (if he did). It appears he did a software upgrade after fighting DDOS attacks for a few days. Maybe some of the automated processes aren’t working the same.

M&P Ultraflex 7 isn’t really optimal for UHF, but I don’t know what the quality is of the BR-400. The name would imply a diameter of 0.40 inches, making it the same diameter as LMR400, but I don’t know if it as good as LMR400 or one of the 10 mm M&P cables for UHF. Going to M&P 10mm cable (hyperflex, Ultraflex, or broadpro) would make a difference in the power that reaches your antenna, but more power doesn’t always mean greater distance. It usually improves the clarity of the signal though. Honestly, if you’re happy I would just leave it alone until for some reason you aren’t. There are many posts that provide a coax loss calculator, try running the calculations to see whether you think it’s worth it or not.

I don’t receive those notifications, but perhaps no changes were input into the database last week.

First, you have to be a premium member. If you paid your $50 and it doesn’t show you as being premium then you’ll have to let @rdunajewski know. Then, you click on “Clubs” in the menu bar and then “Start a Club”

Does it transmit to the handheld while connected to the sw-102? Look for problems with the connector where it attaches to the radio. Maybe post some pictures so we can see how you are connected.

Did you ever post? What’s your call sign?

Are you certain the Anysecu is transmitting? If so then there must be a problem with the connection to the radio.

2. Yes, the repeater owner. Unfortunately, there is no formal coordination in GMRS so coordination relies on repeater owners being proactive and considerate. 3. No, and unfortunately when it does happen this can cause issues for people who are within range of both. There are eight different repeater channels. Unless all eight are taken one of these repeater owners probably should have chosen something else.

If they’re now considered FRS radios then you don’t need to ID, even though you have a license. And you can communicate with someone who has a GMRS radio and they are required to ID but you don’t have to as long as you’re using an FRS radio.

I don’t know what the regulatory status is of that. Look on the Midland website to see if it’s still produced. And make yourself familiar with the FCC regulations here: https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E

I understand your confusion. The FCC messed up. Once upon a time companies were allowed to make dual service radios (FRS and GMRS) but now the regulations do not allow authorization of the combination. At that time there were FRS channels and GMRS channels. 95.1761(d) (d) Effective December 27, 2017, the Commission will no longer issue a grant of equipment authorization for hand-held portable unit transmitter types under both this subpart (GMRS) and subpart B of this part (FRS).

No, not because they have a license but because they’re using a GMRS radio. A person using an FRS radio doesn’t have to ID, whether they have a license or not.