Modification dnt WT 77
Extending the frequency range without hardware modification
The WT 77 from dnt is one of many 'license free' radio-sets working in the 444 MHz range. The device works in the LPD range (69 channels) and also in the PMR range (8 channels). It is also known as TELCOM TE-150 or WT405. The basic idea of the modification origins from the the Internet (sources see below).
Freqencies WT 77
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Figure 1: The dnt WT77 |
There is however a third band available. The third band is the so called K-Band with 4 channels at 444 MHz.
Channel | Frequency (MHz) |
K1 | 444.600 |
K2 | 444.650 |
K3 | 444.800 |
K4 | 444.825 |
Radio operation on these four channels is not allowed in Germany. In order to enable the K-Band the following steps have to be taken.
Step 1: Switch off device
Step 2: Press Volume-Key and ChannelUp at the same time and switch on the device (thus pressing three keys simultaneously). Still hold all keys until a peep sounds. Now release all keys. There should be the following display.
Figure 2: Configuration Menu |
The display P·L means that the device is currently being configured for the P-Band (PMR) and the L-Band (LPD). Using the arrow-keys, several configurations can be chosen from. The best certainly is P·K·L, since there will be all three bands available.
Figure 3: Making all 3 bands available |
Step 3: After confirmation (CONFIRM) a new menu will show up. Within this menu, the output power for the L-Band can be switched from 10mW to 500mW. I do not recommend to use the option HI. First, using more than 10mW is not allowed in Germany (even for radio amateurs when talking to non-amateurs). Second: it is just the nice thing with LPD that the batteries last much longer. So if you really need 500mW, use the P-Band then.
Figure 4: Configuring Output Power |
Step 4: The configuration is finished after confirming either LO or HI. There is a new item in the band-switch menu now. The K-Band is available under the name KDR.
Figure 5: The KDR Band (new) |
Sources