Part number for IC-745 L201 on PLL board - Page 1
Forum section: electronics / rf-microwave

author: hostile
author_rank: Contributor
timestamp: July 18, 2021, 12:25:18 am
content: I tried adjusting the L201 coil and the thing collapsed.The manual list lb-133 coil as the part number, but can not find any reference.The package says b113 on it.Anyone know what value range this is supposed to be in ?Any help is appreciated.

author: bob91343
author_rank: Super Contributor
timestamp: July 18, 2021, 05:10:02 am
content: What are the values of C207 and C208? At what frequency is the PLL running? I suspect one or both capacitors resonate with the inductor so you can get an idea of how much inductance. In what condition is that inductor now?

author: hostile
author_rank: Contributor
timestamp: July 18, 2021, 05:40:22 am
content: I believe it is at 100MHz,C207 measure 39pF, C208 is 22pFthe coil is a variable. plastic housing crumbled and the ferrite slid to the bottom of the canister. Do not think there is any saving it.

author: bob91343
author_rank: Super Contributor
timestamp: July 18, 2021, 06:29:09 am
content: Perhaps you can cobble up an air wound coil and squeeze it to adjust the inductance. Calculate what you need based on the capacitors, and once you have it working you can align it with an orange stick to change the turn spacings.

author: icom_hobbyist
author_rank: Newbie
timestamp: January 10, 2024, 01:59:06 am
content: I've done the exact same thing! The variable coil/inductor crumbled when going through the service manual tuning/alignment adjustment processand I can't find any information or source for the b133 coil. Does any one have a generic or Icom replacement part number for the PLL board's L201 coil? Does anyone know where the part or alternative can be sourced? Thanks in advanceJC

author: tchandler
author_rank: Contributor
timestamp: January 10, 2024, 06:07:03 pm
content: I am having the same problem with IC-751A. L201 on the PLL board, LB-113. I am still able to adjust with very light pressure on the core as I turn CCW. I can just barely reach the target voltage of 3V, but the core is at the ccw limit it seems, so it is very touchy. I cannot put light enough pressure to back it out any further. I melted some beeswax on it in an attempt to keep it in place but its not stable. Every time I check, the voltage has dropped to about 2.9V I want to replace L201 but cannot find any specs.

author: RFDx
author_rank: Regular Contributor
timestamp: January 10, 2024, 07:58:10 pm
content: What exactly crumbled? The ferrite screw, the plastic coil former, ferrite cup? Pictures available?Taking into account the values of the components in the VCO for the IC-745 Sub-PLL, the parasitics of the FET and buffer amp, the capacitance of the varactor diode and the frequency range (115...120MHz) I got an inductance of ~110nH for L201.

author: icom_hobbyist
author_rank: Newbie
timestamp: January 11, 2024, 04:58:30 am
content: I haven't removed the RF shield lid so I can't see L201 very well - however the top of the trimmer suddenly collapsed/dropped-down or gave way and sunk deep into its metal housing as I was gently turning/adjusting it to reach the target of 3 Volts. I suppose the plastic coil former cracked/crumbled but I don't really know yet as I haven't removed the component for a thorough inspection. I would like to be able to replace it but but cannot find any specs.Update:from ICOM technical support"Thank you for contacting Icom America.Unfortunately we do not have any specs on the coil. The part number is 6130000870 in which you can contact our Parts Team for availability, and pricing.Click here for information regarding Warranty Registration, Service/Repair Authorization form, Knowledge Base & Technical Support:http://www.icomamerica.com/support/"

author: tchandler
author_rank: Contributor
timestamp: January 31, 2024, 04:27:33 pm
content: Pictures in case it helps.I was able to verify the operating frequency as 115Mhz to 120Mhz increasing as I increase VFO on each band relating to 3V - 1.5V lock voltage on R202 (IC-751A) .Measured in circuit with an LCR meter I get 9.5uH. I may remove it and try to measure out of circuit.

author: tchandler
author_rank: Contributor
timestamp: January 31, 2024, 09:00:28 pm
content: I had to zero adjust the LCR meter, now reading 0.1uH out of circuit. I'm going to go ahead and get these two from digikey and try them.292SNS-T1366Z Q50 @ 80MHz292KNAS-T1028Z Q35 @ 50MHz

author: icom_hobbyist
author_rank: Newbie
timestamp: February 02, 2024, 12:23:19 am
content: Can someone tell me what the small white cylinder circled in the attached picture of the antenna relay board is? I'm guessing some kind of choke, but I don't know what the part/part number is.

author: p.larner
author_rank: Frequent Contributor
timestamp: February 02, 2024, 12:27:30 pm
content: I would think its a glass cassed resistor to bleed static from the antenna.

author: RFDx
author_rank: Regular Contributor
timestamp: February 02, 2024, 08:58:22 pm
content: Quote from: icom_hobbyist on February 02, 2024, 12:23:19 amPA-Unit: R35 - Surge Absorber - DSA301It's a Mitsubishi 300V gas discharge tube (GDT). You could use any other GDT with similar voltage and surge current rating.https://uk.rs-online.com/web/p/gas-discharge-tubes/5258888https://www.digikey.de/de/products/detail/mitsubishi-materials-u.s.a.-corporation/DSA-301LA-05(UL)/11306216?utm_source=findchips&utm_medium=aggregator&utm_campaign=buynow

author: tchandler
author_rank: Contributor
timestamp: February 02, 2024, 10:06:30 pm
content: Quote from: icom_hobbyist on February 02, 2024, 12:23:19 amThe circled item is likely a ferrite core, it's on many of the jumpers but not most. I can't find any spec but I did find similar on mouser. You might be able to get by without it.

author: tchandler
author_rank: Contributor
timestamp: February 02, 2024, 11:06:29 pm
content: I have installed 292SNS-T1366Z for L201 and I am able to complete alignment of the PLL board. I still have to pull it out and install the shields, check/realign and test the radio but it looks like it will work.

author: icom_hobbyist
author_rank: Newbie
timestamp: February 04, 2024, 02:14:13 am
content: That's awesome!