Batboard

We have a large fleet of HT-1250 portables, (about 1000 radios )that have various Tanapa numbers. The most common are PMUD 1481A-D and PMUD 1482 A-D. We are about half way through narrow banding our fleet and recently have had the following problem arise. The radios with PMUD 1482 Tanapa's when programmed for 12.5 kc bandwidth cut out at 3.8 kc deviation, the PMUD 1481 do not. Is there a different filter on the boards, and am I going to have to create a special codeplug at 25 kc bandwidth and turn down the deviation?

H25KDF9AA5 PMUD1482B Conv Pref nkp vhf


H25KDH9AA6 PMUD1481A Conv Pref kp VHF

What do you mean they cut out at 3.8KHz deviation? They will unmute properly with signals with a higher deviation then they are programmed for? Sounds like a trip to the service monitor for a tuneup will be a good place to start. Also what is the firmware version of these boards?

All testing is being done with a General Dynamics r2625c service monitor. When the radio with the 1482 tanapa is programmed for 12.5 bandwidth the radio cuts out with 1kc of audio with 3.8 kc deviation at 1uv or above signal level. It appears that the Tanapa1482 crystal filters are a little more selective than the Tanapa1481 ones with the same 12.5kc bandwidth programming.

Assuming that you're speaking of receive on the HT1250, I would expect that at 3.8 Khz of deviation, you'd be banging the hell out of the receive IF filters, and I'd expect it to "cut out". The nominal deviation for 12.5 Khz channel spacing in the U.S. is 2.5 Khz, so the occupied bandwidth by Carson's rule is roughly 12 Khz, and that should fit with a little "room" to spare in 12.5 Khz BW IF filters.

RADIOMAN2002 wrote:All testing is being done with a General Dynamics r2625c service monitor. When the radio with the 1482 tanapa is programmed for 12.5 bandwidth the radio cuts out with 1kc of audio with 3.8 kc deviation at 1uv or above signal level. It appears that the Tanapa1482 crystal filters are a little more selective than the Tanapa1481 ones with the same 12.5kc bandwidth programming.

You are sending 3.8KHz of deviation into a radio programmed for 2.5KHz deviation on receive and are wondering why the audio cuts when you overload the radio with deviation, but the radio works OK with less than 3.8KHz of deviation? Am I understanding this correctly?

Yes you are, but you didn't read the whole post, I am questioning the different Tanapa's. One cuts out at 3.8 kc (1482)and the other at 8kc (1481)both programmed for 12.5 kc bandwidth. The reason this is a problem is very simple, you don't mearly throw a switch and ALL 1000 of your radios become narrow band instantly (unless you buy ICOMS) so there is now about a 50/50 split of narrow and wide band programmed radios out there, that's where the problem come in. A narrow radio talking to a wide radio just has low audio, but a wide talking to a narrow cuts off. I was wondering if anyone else has seen this problem with different Tanapa's.

Radioman, I feel your pain on the narrowband conversion process. I see what you're trying to accomplish and I know of people who have done it that way and had zero problems. The only way to do it correctly though is to program a wide band and a narrowband channel in the radio and get them to switch between channels if possible. I know it flat out sucks, but you aren't the only person in this country with that delimma right now. I have also begged and pleaded with Motorola to take Icom's solution into the picture but it seems like it falls on deaf ears. I guess if they didn't think of it they don't like it. It kinda ticks you off though when something as simple as a push of a button could make the process so much easier.

Correct. Add the narrowband channel as you go along, everyone stays on wideband until everyone has narrowband, then you take the wideband out of the radio. This is basically a once in a lifetime programming deal,obviously it won't become a yearly thing.

Unfortunately not an option, more than 50% of the radios have been reprogrammed. Only the 1482A Tanapa is a problem there are a half a dozen other Tanapas we have that also don't cut off at 3.8kc.
Ok I guess the best solution is a special file just for the 1482A, I am going to use 20 kc bandwidth and tune down the deviation. PL isn't a problem since we don't use any. At least until the base stations are replaced next year.

RADIOMAN2002 wrote:Unfortunately not an option, more than 50% of the radios have been reprogrammed. Only the 1482A Tanapa is a problem there are a half a dozen other Tanapas we have that also don't cut off at 3.8kc.
Ok I guess the best solution is a special file just for the 1482A, I am going to use 20 kc bandwidth and tune down the deviation. PL isn't a problem since we don't use any. At least until the base stations are replaced next year.

Interesting. When we made the leap to narrowband, We programmed the repeater output as narrow band while leaving the input as wideband. The only effect noticed was that some HT1250 style radios and some CDM1250's had lower than average CTCSS transmit tones when programmed for narrowband. When their CTCSS was turned up to .35 KHz dev from the typical .29 -.30 Khz dev, they stopped being intermittant into the repeater. Once all the radios were programmed, we then programmed the input of the repeater to be narrow band too. We only touched the radios once, making all the channels be programmed as narrowband.
During the change over, some users only noticed that some stations were a bit louder than others. A slight twist of the volume control took care of most of the receive volume issue. Since we didn't tell the users too much about what we were doing, the amount of "issues" was minimal. I'm a firm believer that if you inform them of the inside details, they will complain about these changes. If you just say they need an "upgrade" , they think they are getting improvements and don't look for problems. For those who actually complained about the receive audio level, we told them that we could "fix" this with more programming (?) but they would have to come back again for programming. For the most part, everyone didn't want to have to come back for programming and decided to live with for the duration of the programmng cycle.

B.

With over 100 base stations, it's not a quick switch. I agree that letting anyone other than radio personel know what going on is a disaster waiting to happen. I myself have notice the same with the bases being louder than the mobiles already narrowed, but no one else has, and I'm not telling them about the difference. We don't use PL so that's not an issue. The other problem looming is that all the bases are going to be replaced, so they are not getting the narrow banded profile. It is just strange that only the 1482 Tanapa is causing problems. I guess that Tanapa is the true narrow band one, while the others were just an intermediate. After some more checking I think the best solution is to set the radio for 20kz and then adjust the deviation as needed. When the radios come around again after 1-1-13 we can load a true narrow profile in them, and retune them.