{"id":3805,"date":"2023-09-03T09:02:46","date_gmt":"2023-09-03T03:32:46","guid":{"rendered":"https:\/\/johnsonfrancis.org\/techworld\/?p=3805"},"modified":"2024-02-09T05:25:18","modified_gmt":"2024-02-08T23:55:18","slug":"peeping-inside-my-tm-261-vhf-base-station","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/techworld\/peeping-inside-my-tm-261-vhf-base-station\/","title":{"rendered":"Peeping Inside My TM 261 VHF Base Station!"},"content":{"rendered":"

Peeping Inside My TM 261 VHF Base Station!<\/span><\/h2>\n

My quarter century old TM 261 VHF base station was resting in the attic for a decade, when I took it out in March 2023 after getting my Amateur Radio license renewed. Naturally there was a lot of dust over it which was immediately cleared. What escaped my attention was the dust collected between the fins of the large heat sink. Luckily, the base station was still working, though the volume control knob had disappeared. But there was a snag, it would work only on low power.<\/p>\n

\"\"<\/p>\n

Though it shows the display in higher power modes, output was obviously not going out into the antenna as I could not access the local repeaters. Even in low power, the performance was not stable, as I was missing contacts on the repeater sometimes. Hence I decided to have a look inside the radio on what could be wrong.<\/p>\n

Downloaded the service manual after a Google search and skimmed through it. I could understand that there are two top and bottom panels which can be removed by unscrewing a couple of star edged screws. After cleaning the dust between the fins of the heat sink, I removed the screws from the top panel first. I could see the speaker and circuitry inside.<\/p>\n

Speaker could be detached easily to see the inside circuitry better. I could not locate any gross abnormality and I do not have any of the equipment needed for testing as mentioned in the service manual. All I had was a digital multi-meter. Searched Google once again and learned that the prominently seen TOSHIBA S-AV17(K2) is the RF power amplifier module.<\/p>\n

\"\"<\/p>\n

I saw that a couple of electrolytic capacitors were sticking together as if glued together at the top. I gently separated them out and that was the only ‘service’ I could perform inside! I placed the lid back and opened the lid on the other side, just to have a view inside. Again, nothing seemed to be burned out or anything. Everything looked ‘fine’ for a quarter century old radio. I had expected a lot of dust inside and had hoped that cleaning would help.<\/p>\n

\"\"<\/p>\n

But there was hardly any dust to be found inside! Put back the lid and switched on the radio once again. Everything was back to square one. There was no improvement in performance and luckily there was no worsening of performance. So for the time being, this will remain as a standby radio for use on local repeater. My aspiration of using it as a second radio for accessing amateur radio satellites was shatterred!<\/p>\n

\"\"<\/p>\n","protected":false},"excerpt":{"rendered":"

Peeping Inside My TM 261 VHF Base Station! My quarter century old TM 261 VHF base station was resting in the attic for a decade, when I took it out in March 2023 after getting my Amateur Radio license renewed. Naturally there was a lot of dust over it which was immediately cleared. What escaped […]<\/p>\n","protected":false},"author":1,"featured_media":3808,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-3805","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-amateur-radio-ham-radio"],"yoast_head":"\nPeeping Inside My TM 261 VHF Base Station! - Johnson's Techworld<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/johnsonfrancis.org\/techworld\/peeping-inside-my-tm-261-vhf-base-station\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Peeping Inside My TM 261 VHF Base Station! - Johnson's Techworld\" \/>\n<meta property=\"og:description\" content=\"Peeping Inside My TM 261 VHF Base Station! 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