R100 VCO

[KD8DWU]

Hello,
I am pulling my hair over 2 R100 repeaters that I have. I got both of them used and they do work in the Freq. they are labeled for (RX - 469.975 -- TX - 464.975) there are slight differences between the two, one is DPL and the other is PL & One has limited features installed in the Control board on the lid while the other is loaded. My problem is tuning them into the Ham band. Below is what I have done thus far and my results:

- First I made a Programming Cable and then checked the Programmed Freq's in the R100 -- Read TX/RX OK.
- Second I tested that is working as it is suppose to, The Freq's they are programmed for, It is repeating, PL/DPL is right etc.
- Third I reprogrammed it within the factory limit TX and RX with a 5meg split to verify my cable and programming software are working as they should and then tested it again on the bench -- still working as it is suppose to with the new Freq's.
- Forth I did the Hex on the Programming Software and reprogrammed it into the Ham Band (RX - 448.175 -- TX - 443.175) wrote it to the Radio and then Read the radio again to verify that it took it -- It accepted the new range and Freq's I put in, now says it is RX - 448.175 -- TX - 443.175.
- Now when I connect my VM to the Ground and SL test point it gives me a Voltage reading of say 6.5vdc but when I push the PTT button on the board and try to adjust the TX VCO trimmer C221 it has no effect on the SL Voltage, it continues to read 6.5vdc while PTT is pressed and tuning C221.
- I have also rebooted the laptop and rechecked the programmed Freq's and it is at RX - 448.175 -- TX - 443.175.

Both R100's act the same when trying to get them to work in the Ham Band. Is there something I am doing wrong? I find it hard to believe they both have the "Same" Problem. If I left out any needed information please let me know.

Thanks for any help,
Gene
KD8DWU

[Will]

There is a known problem with the trimmer capacitors going bad.. tarnishing.

There is a mod to replace the trimmer with a fixed value ceramic chip cap, and replacing the VCO coil with one that has a tuning slug.

[KD8DWU]

Thanks Will for the info. I have heard that before but have never seen any Given Values for the Fixed Cap or VCO Coil when you replace them. I assume that is because they would be Frequency dependent but would also think that to bring it into the Ham Band would be known values for those components? If you have any idea of the replacement parts Values, could you let me know?
Thanks again for the help.

I think I have discovered my problem, with help from a local Ham who is also a member here. I plan to do some more testing this evening and find out if I have. If so, it was not a Hardware Based problem, Let's call it ............. "User Error"

Gene

[Will]

Gene,

I will look up the values and send them in PM.