Gunung Serapi radio stations have intermodulation interference in the vicinity of Bukit Djin tower at Jalan Batu Lintang in Kuching, Sarawak. What's the solution to eliminate the intermodulation interference?

In Kuching, the radio stations are mostly transmitted from either Gunung Serapi or Bukit Djin. 

Gunung Serapi are used by Hot FM 94.3MHz, Cats FM 99.3MHz and RTM radio stations, meanwhile rest radio stations are transmitted from Bukit Djin.

Near Bukit Djin tower at Jalan Batu Lintang, Gunung Serapi transmitted radio stations are having strong radio signals mix in the vicinity of Bukit Djin tower such as Batu Lintang and Westwood in Kuching, Sarawak. This is actually an intermodulation interference.

Until today, there is no solution of intermodulation interference in the vicinity of Bukit Djin tower.

Personally I suspect that the intermodulation interference to Gunung Serapi radio stations frequencies in the vicinity of Bukit Djin tower is caused by poor RF filter.

In my opinion, to solve this intermodulation interference, I suggest all Kuching commercial radio stations move out from Bukit Djin tower and transmit the signal in Gunung Serapi with low power transmitter (0.5kW or 1kW), but several radio stations may need to change frequency when they move to Gunung Serapi.

Gunung Serapi has two towers located in lower and upper peak. Cats FM, Hot FM and RTM radio stations are transmitted from Upper Gunung Serapi, so Bukit Djin transmitted commercial radio stations can use either upper or lower Gunung Serapi, subject to the tower space availability.

Many commercial radio stations can retain their frequencies if they move to Gunung Serapi like Hitz FM 95.3MHz, Era FM 96.1MHz, MY FM 96.9MHz, Mix FM 97.7MHz, Eight FM 98.3MHz, Lite FM 100.1MHz, Sinar FM 102.1MHz, Tea FM 102.7MHz, Bernama Radio FM 100.9MHz, and Kupi-Kupi FM Sarawak 92.5MHz, but radio stations such as IKIM FM, Melody FM, Eight FM, and Kool 101 need to change frequencies due to interference to other radio stations within the coverage.

* IKIM FM 93.7MHz

- Suggested frequency: 93.4MHz

- Reason: Interference to RTM Ai FM 93.6MHz Bukit Kayu Malam coverage in Roban and Saratok. The minimum frequency separation between Gunung Serapi and Bukit Kayu Malam is 200kHz.

* Kool 101 FM 104.3MHz

- Suggested frequency: 104.4MHz

- Reason: Interference to RRI Pontianak PRO-1 FM 104.2MHz in West Kalimantan, Indonesia 

* Melody FM

- Suggested frequency: 103.5MHz or 103.6MHz

- Reason: Interference to RTM Traxx FM 103.8MHz Bukit Temudok coverage in Sri Aman, Sebuyau, Pusa and Maludam. The minimum frequency separation between Gunung Serapi and Bukit Temudok is 200kHz, not 100kHz.

Another solutions are to reduce the signal-noise-ratio (SNR) of Bukit Djin radio stations and using good quality RF filter to prevent frequency leaking to other frequencies which results intermodulation interference.

I strongly suggest MCMC and Telekom Malaysia to look into this matter and provide a proper solution of intermodulation interference, so the radio listeners who tune RTM radio stations, Hot FM and Cats FM at Jalan Batu Lintang can tune the radio properly without intermodulation interference.

FM DX: Sematan, Sarawak

On 31st August 2025, in conjunction with Merdeka holiday, I paid a visit in Kuching, mainly for radio DXing activity as per planned in early 2025. Alongside Kuching, I also visited Sematan and Serian.

Sematan was my destination of radio DXing after landing at Kuching airport. It takes 90 minutes to travel from Kuching to Sematan.

Bukit Djin transmitted radio stations can be tuned clearly up to Bau only, the signal become weak and zero after Bau when heading to Sematan, weak to zero signal in Lundu when I drove on PAN Borneo Highway, but Bukit Djin radio stations signal are back with weak condition in Sematan town.

In Sematan, I had managed to receive 9 distant radio stations randomly.

1. Hitz FM 95.3MHz Bukit Djin (70km)

2. Lite FM 100.1MHz Bukit Djin (70km)

3. Mix FM 97.7MHz Bukit Djin (70km)

4. Sinar FM 102.1MHz Bukit Djin (70km)

5. Eight FM 98.3MHz Bukit Djin (70km)

6. Tea FM 102.7MHz Bukit Antu/Djin (70km)

7. RTM Sibu FM 94.6MHz Bukit Kayu Malam (184km)

8. RTM Sri Aman FM 89.5MHz Bukit Temudok (199km)

9. Radio Republik Indonesia RRI Entikong PRO-1 FM 99.9MHz (123km)

Gunung Serapi transmitted Kuching radio stations are loud and clear in Sematan, IKIM FM 93.7MHz from Bukit Djin has interference with RTM Ai FM 93.6MHz from Bukit Kayu Malam (Sarikei) there.

I had recorded 6 Bukit Djin transmitted Kuching radio stations randomly in Sematan, Sarawak. Mix FM 97.7MHz and Hitz FM 95.3MHz are the clearest, but Lite FM 100.1MHz, Sinar FM 102.1MHz, Tea FM 102.7MHz and Eight FM 98.3MHz are not so clear in Sematan.

RTM Sri Aman FM 89.5MHz is the furthest radio station tuned in Sematan, Sarawak. For RRI Entikong PRO-1 FM 99.9MHz in Sematan, signal is extremely weak like what I tuned in Kuching and Bau.

Although Sematan is located at westernmost in Sarawak, I also attempted to check any Johor radio stations (Gunung Pulai/Bukit Tinggi) whether they can be received there or not. Technically, no overspill signal from Gunung Pulai or Bukit Tinggi can be detected in Sematan, Sarawak. (Example: Receiving RTM Johor FM 101.9MHz from Gunung Pulai in Sematan, Sarawak, but no signal)

Visiting Kuching, Sarawak during Merdeka holiday on 31st August 2025, RRI Entikong PRO-1 FM 99.9MHz is the only DX radio station tuned there.

Here are the photos of me visiting Kuching, Sarawak during Merdeka holiday.

In Kuching, there is no unique DX radio stations tuned there like other Sarawak towns like Simanggang, Sarikei, Miri and Bintulu, but Radio Republik Indonesia RRI Entikong PRO-1 FM 99.9MHz is the only distant radio station in Kuching, but strong interference noise from Lite FM 100.1MHz (Bukit Djin).

74km distance to receive RRI Entikong PRO-1 FM 99.9MHz from Entikong in Kuching, Sarawak, Malaysia.

Serian is the clearest location in Sarawak, Malaysia to tune Radio Republik Indonesia RRI Entikong PRO-1 FM 99.9MHz

Do you know that Radio Republik Indonesia RRI Entikong PRO-1 FM 99.9MHz can be tuned in some areas of Sarawak, Malaysia?

RRI Entikong PRO-1 FM 99.9MHz is from West Kalimantan Province, but Entikong District where is located near Sarawak's Serian border.

This radio station can be tuned loudly and clearly in Serian, Sarawak on the same frequency. RRI Entikong PRO-1 FM 99.9MHz is the only Indonesia radio station available in Serian, Sarawak.

Its RDS PS text is DB64-FM which is a default PS text of Deva Broadcast DB64-FM audio processor, I saw the text yesterday when I was in Serian with a friend.

It is extremely weak and almost zero signal if I tune RRI Entikong PRO-1 FM 99.9MHz in Kuching and Bau.

In Kuching and Bau, Radio Republik Indonesia RRI Entikong PRO-1 FM 99.9MHz is the only DX radio station, but signal is very weak with strong interference from Lite FM 100.1MHz Bukit Djin transmitter.

Overall, although RRI Entikong PRO-1 FM 99.9MHz only serves Entikong District, West Kalimantan, Indonesia, but it is available loudly and clearly in Serian Division, Sarawak, Malaysia on same frequency.

RRI Entikong PRO-1 FM 99.9MHz is not DX radio station in Serian, Sarawak, Malaysia in terms of tuning distance from the transmitter site.

Formerly it was on FM 100.7MHz before June 2025.

- Frequency: FM 99.9MHz

- Power: 5kW

- Transmitter site: LPP RRI Entikong, Jl. Lintas Malindo No.102, Dusun Semeng, Semangit, Entikong Sub-district, Sanggau Regency, West Kalimantan Province, Indonesia

- Receiving sites: Serian, Sarawak, Malaysia

- Distance: 36km