Re: UHF Range: Partial RX/TX Issue.
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Just chucking this out there but surely the signal passes through the 70cm BPF? If anything in the 70cm BPF has come adrift then the radio will have a broken signal path. Is it possible soon as you go to 460mhz a relays (pin diodes) on nearly all radios switch out the BPF and onward. If the switching at 460mhz has switched out the bad BPF then this may be why it suddenly bursts into life.
? I believe the diodes (noisy diodes are 1N5711 or BAT85’s) so may be worth checking those and the BPF relays.
? I’m trying to find a schematic for the FT847 but only find the technical supplement.
? I will tune my FT847 near 460mhz and listen to any switching but I’m sure it does as it’s the beginning of band IV tv transmissions here in the UK before DVB-T
de Spence M0STO Sent while portable! please excuse typos.
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On 4 Sep 2022, at 15:02, Andrew Lenton < a@...> wrote: I have further read this, and it makes no sense, it seems you have a corruption, or an illegal settings near the CPU ? Check this site and let me know what you find: ?
? 73 ? Andrew ? ? Hi all, I have a rather strange issue with my '847 that I haven't yet figured out the cause for: It doesn't receive or transmit between 420 MHz and 459..9995 MHz.
Background info: I'm 3rd owner of my nearly mint condx.? My understanding is that it has never been modded or altered in anyway.? An examination of some of the circuit boards shows no signs of tampering/repair or component damage. The radio functions perfectly in every sense, transmits and receives in all 5 modes without issues on all amateur bands (except 440 MHz band of course) and receives perfectly fine on HF and VHF general coverage receive, and receives perfectly fine at 460 MHz up to 512 MHz.? No other anomalous functionality except that I just discovered during my trouble shooting session that I cannot enable the Alaska 5167 kHz emergency channel in the menu, and that my radio will transmit at 460 Mhz and up.? That last bit piques my attention as my understanding is that these radios cannot transmit out of band unless someone has done a mod?
When I select any 70 cm frequency and key the radio, the speaker audio cuts off normally and I hear the cooling fan step up in speed from it's normal stand-by cooling speed like it normally does on any other band.? "Transmit" appears on the display, but no PO level, nothing, no matter what mode I use.? Using a couple of dual band radios confirmed to be working (I hear them perfectly on a pair of Icom R7000's) there is a definite gap between 420 MHz and 459.9995 MHz where nothing is heard or can be sent.? But the moment I go to 460 MHz and higher it will receive and transmit.? I do not hear a change in the receive static in the affected frequency region as I scroll up in frequency.? I've performed the CPU reset with no resulting change in behaviour.? Owned the radio for over 5 years but i've never used it on 440 MHz before so I do not know how long this issue has existed.
Any ideas before I break out the magnifying glasses and schematics? This email has been scanned by BullGuard antivirus protection.
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Spence G5STO