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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
Jordan All Messages By This Member #530 ? Hi group... ? I'm not finished working on my 450S, but i've got to say that the 450 and 850 service manuals contain some very poorly written translations from Japanese, and also some errors in the alignment instructions that take some time to decipher and adapt to the correct alignment methods... ? More later....73...Jordan VE6ZT toggle quoted message Show quoted text ----- Original Message ----- From: Jordan via groups.io To: [email protected] Sent: Sunday, March 23, 2025 2:49 PM Subject: Re: [Kenwood-Amateur-Radio] TS-450S BCB sensitivity 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 ----- 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
W6KX All Messages By This Member #531 Jordan, ? As much as you can share on your findings and solutions would be much appreciated.? I understand the idea but haven't understood how to use the adjustment mode relative to the Adjustment tables. Mike

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