| Electronics > Repair |
| CMU200 Rx level issue / failed loop test |
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| Michael-VK2BEA:
--- Quote from: Sas on January 07, 2022, 09:15:51 am ---Where did you buy DFC3R836P025HHD ? --- End quote --- The replacement 836 filter I canablalised from another board bought on eBay (from the TX side .. it also has corroded RX side filters) I placed an order for the BHD version on the dubious site I mentioned earlier (ecTransistors.com) but have not heard anything from them despite several emails. The 'order' still shows pending and the PayPal payment is the 'approved' state. I'm not optimistic though. After seeing Wim's message the other day, I did another search and found some (BHD) on eBay which I ordered. (I had looked on eBay previously but not found this) The really curious thing is that the price on the dodgy site and the eBay seller are identical (except they added a bunch of fees and taxes). Maybe its someone scraping eBay and then charging high shipping and fees. BTW .. If you need just a couple, send me a message. Michael |
| Sas:
--- Quote from: Michael-VK2BEA on January 07, 2022, 09:24:37 pm ---After seeing Wim's message the other day, I did another search and found some (BHD) on eBay which I ordered. (I had looked on eBay previously but not found this) --- End quote --- I ordered BHD filters on 23 Dec 2021 from the same ebay source. Theoretically, the package is flying to me. I wonder who will get first :) (USA vs Europe send 29 Dec 2021). If I did not get it within a month then I will send a message. According to the IEEE MTT (thanks a lot) that you posted, BHD filters can be older type filters, with an electric wall. I still have to wait for the MMIC amplifiers to the RF3 output, I can't do anything else until the parts are delivered. |
| Michael-VK2BEA:
--- Quote from: Sas on January 10, 2022, 03:55:00 pm ---According to the IEEE MTT (thanks a lot) that you posted, BHD filters can be older type filters, with an electric wall. I still have to wait for the MMIC amplifiers to the RF3 output, I can't do anything else until the parts are delivered. --- End quote --- Unfortunately it's going to be difficult to get it to fit. I'm thinking that it might need an intermediate PWB (with castelated edge 1/2 holes) to mount the BHD and lift the end of the (bigger) filter over some other smd components. |O Michael |
| _Wim_:
I can happily report that the BHD type filter can be bodged on with good results :-+ Probably not ideal as not all the filter castelations are grounded, but seems to work ok. I first covered the small components above the filter with capton tape to prevent shorts, then moved the small cap at the input of the filter a little to the side (but still on its original pad), aligned the filter such that the cap fitted just inside the castelation input of the filter, and the solder the ground and the output of the filter. Covered the new filters with capton tape to prevent future corrosion from the RF absorbers and reassembled. All tests past, even the FM Calibration that failed before! Remark: removing the 836MHz original filter was not easy. I do not know if this was related to my soldering abuse from before, but I had a hard time getting the filter of the board. Luckily nothing got damaged in the process. |
| Michael-VK2BEA:
I didn't notice before but your layout is different than my RXTX board. In mine the 936 MHz filter is at the edge of the board. |
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