FT-891 back from Yaesu, 11 days R/T
. They've seen this issue before. Radio seems to run cooler. I’m flustered at how long it took me to realize the ‘low noise level’ was from no Receive. I need a better sense of humor.
Shortcomings aside, SMT diode failures like this are what kept failing in my Alinco DX-70 so it looks like the problem may be me.
KK5DR published an article several years prior (https://www.qsl.net/kk5dr/Swampedinput.pdf) about the value of placing an LPF between Exciter and Amp to attenuate UHF/VHF that can damage Transceiver. I think that’s my best bet and I already saw how it played-out with my Alinco (RIP). I got lucky this time, it was covered by Warranty.
AliExpress has a listing for an LPF board with 4 relays for 4 distinct bands from 10, 20, 40 & 80. Link: https://www.aliexpress.us/item/3256802966589453.html Ad include attenuation chart. What are these boards intended for anyway? They run about $40 and are sold on every electronics site so it must be moving product-wise. Relay switched bands should be better than a standard TVI filter (like I already have).
Is this idea overkill? KK5DR singles out grid-driven tetrodes with resistive inputs. I sort of have that with a 6:1 Unun feeding a 300 ohm resistor to ground and it works fine. Have a large Johnson tunable TVI filter but a band selectable filter would feel better on PTT and it’s a lot smaller so it doesn’t need another patch cord. Am I on the right track here?
neil, NYC
. They've seen this issue before. Radio seems to run cooler. I’m flustered at how long it took me to realize the ‘low noise level’ was from no Receive. I need a better sense of humor.Shortcomings aside, SMT diode failures like this are what kept failing in my Alinco DX-70 so it looks like the problem may be me.
KK5DR published an article several years prior (https://www.qsl.net/kk5dr/Swampedinput.pdf) about the value of placing an LPF between Exciter and Amp to attenuate UHF/VHF that can damage Transceiver. I think that’s my best bet and I already saw how it played-out with my Alinco (RIP). I got lucky this time, it was covered by Warranty.
AliExpress has a listing for an LPF board with 4 relays for 4 distinct bands from 10, 20, 40 & 80. Link: https://www.aliexpress.us/item/3256802966589453.html Ad include attenuation chart. What are these boards intended for anyway? They run about $40 and are sold on every electronics site so it must be moving product-wise. Relay switched bands should be better than a standard TVI filter (like I already have).
Is this idea overkill? KK5DR singles out grid-driven tetrodes with resistive inputs. I sort of have that with a 6:1 Unun feeding a 300 ohm resistor to ground and it works fine. Have a large Johnson tunable TVI filter but a band selectable filter would feel better on PTT and it’s a lot smaller so it doesn’t need another patch cord. Am I on the right track here?
neil, NYC
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