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TS-450S BCB sensitivity

Jordan All Messages By This Member #483 ? Well, I replaced the diodes and it didn't make any difference...Time to make some dinner...73...Jordan... toggle quoted message Show quoted text ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Friday, March 14, 2025 2:27 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Ooops...it should read "...which formed part of the BCB attenuator..." ? 73...Jordan... ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Friday, March 14, 2025 2:23 PM Subject: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Hi group.. ? I have a 450S which has served me very well for ~30 years now. Long ago, I jumpered the resistors which formed part of the BCB, effectively removing the attenuator. It was fine for years like that, but a few months back I noticed a drop in BCB sensitivity. ? All other bands are fine... ? I checked everything I could, replaced the jumpers and verified the ckt, to no avail. I checked the control line for that?band at the 74LS245 and found what I thought was the problem, so this morning I replaced that IC. ? It didn't solve the problem. The only other thing I can think of is that one of the 2 RLS135 diodes for that band might be flaky so I checked them as diodes and they test fine. ? Is it possible that these diodes might operate fine for DC but not for RF...? ? I think I'll replace those two diodes and check again, but this has me a little stumped... ? 73...Jordan VE6ZT
Jordan All Messages By This Member #495 ? I've made a few "discoveries" about the root of the BCB?problems I have?been having. Should I post my findings here or on the 850S page...? ? 73...Jordan VE6ZT toggle quoted message Show quoted text ----- Original Message ----- From: Jordan Arndt To: [email protected] Sent: Friday, March 14, 2025 4:37 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Well, I replaced the diodes and it didn't make any difference...Time to make some dinner...73...Jordan... ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Friday, March 14, 2025 2:27 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Ooops...it should read "...which formed part of the BCB attenuator..." ? 73...Jordan... ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Friday, March 14, 2025 2:23 PM Subject: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Hi group.. ? I have a 450S which has served me very well for ~30 years now. Long ago, I jumpered the resistors which formed part of the BCB, effectively removing the attenuator. It was fine for years like that, but a few months back I noticed a drop in BCB sensitivity. ? All other bands are fine... ? I checked everything I could, replaced the jumpers and verified the ckt, to no avail. I checked the control line for that?band at the 74LS245 and found what I thought was the problem, so this morning I replaced that IC. ? It didn't solve the problem. The only other thing I can think of is that one of the 2 RLS135 diodes for that band might be flaky so I checked them as diodes and they test fine. ? Is it possible that these diodes might operate fine for DC but not for RF...? ? I think I'll replace those two diodes and check again, but this has me a little stumped... ? 73...Jordan VE6ZT
David All Messages By This Member #498 开云体育 Jordan, I'd place your findings here. What did you find? ?
Jordan All Messages By This Member #499 开云体育 Hi David... ? I'm not finished my investigation...I'll need another day or three...73...Jordan VE6ZT toggle quoted message Show quoted text ----- Original Message ----- From: David via groups.io To: [email protected] Sent: Sunday, March 23, 2025 6:09 AM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Jordan, I'd place your findings here. What did you find? ?
Jordan All Messages By This Member #500 ? Group... ? If there is someone with a TS-450S who can check the change in sensitivity crossing the 499 to 501khz and 1704.00 to 1706.00khz points (where the BCB attenuator is switched in and out) I would really appreciate it...Even better if you have a signal generator and can tell me the S-Meter changes at those frequencies... ? I'm trying to limit the number of times I have to pull the RF board because of the stresses and strains?on the board, connectors and thru-holes... ? Thanks...Jordan VE6ZT toggle quoted message Show quoted text ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Saturday, March 22, 2025 3:35 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity I've made a few "discoveries" about the root of the BCB?problems I have?been having. Should I post my findings here or on the 850S page...? ? 73...Jordan VE6ZT ----- Original Message ----- From: Jordan Arndt To: [email protected] Sent: Friday, March 14, 2025 4:37 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Well, I replaced the diodes and it didn't make any difference...Time to make some dinner...73...Jordan... ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Friday, March 14, 2025 2:27 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Ooops...it should read "...which formed part of the BCB attenuator..." ? 73...Jordan... ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Friday, March 14, 2025 2:23 PM Subject: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity Hi group.. ? I have a 450S which has served me very well for ~30 years now. Long ago, I jumpered the resistors which formed part of the BCB, effectively removing the attenuator. It was fine for years like that, but a few months back I noticed a drop in BCB sensitivity. ? All other bands are fine... ? I checked everything I could, replaced the jumpers and verified the ckt, to no avail. I checked the control line for that?band at the 74LS245 and found what I thought was the problem, so this morning I replaced that IC. ? It didn't solve the problem. The only other thing I can think of is that one of the 2 RLS135 diodes for that band might be flaky so I checked them as diodes and they test fine. ? Is it possible that these diodes might operate fine for DC but not for RF...? ? I think I'll replace those two diodes and check again, but this has me a little stumped... ? 73...Jordan VE6ZT

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