I have a Yeasu FT2100b that when i power it on and switch from standby to operate it keys up even with no radio key up asking suggestions where to start looking on this amp to solve this problem. Thanks Jimbo165
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Yeasu FT2100b stays keyed
- Thread starter Jimbo165
- Start date
Do you know if this amp was modified to install an RF keying circuit? They do not have one from the factory and are intended to be keyed with a wire from the radio.
If a CBer used it and didn't add a RF keying circuit, they probably shorted the two screws on the back of the amp marked "Key' and "ground". Then they would have to manually switch from standby to operate in transmit.
If a CBer used it and didn't add a RF keying circuit, they probably shorted the two screws on the back of the amp marked "Key' and "ground". Then they would have to manually switch from standby to operate in transmit.
Shockwave it is still stock I believe no keying added they had a foot switch screwed on back screw to key and ground to have keyup. I found white with orange stripe wire going to relay unsoldered and put in line a keying switch and relay keys and unkeys no problem so relay is good do not want to leave it this way. Also noticed tubes seem to still get color even when relay unkeyed using this switch so they are still acting keyed up. Hard to check switches hate to shoot this amp down the road it looks like new. Is there some type of problem with biasing? Thanks For the help also Jimbo165
Something is wrong because they use the open coil voltage across the relay when it's not keyed to bias the tubes into cutoff. If you have rewired the relay in some way, you probably have bypassed the bias cutoff circuit.
Pull up a schematic online for the amp and restore the wiring exactly the way it was. Make absolutely sure there is no jumper on the back 4 screw terminals causing it to stay keyed. It is the "RY" and either "E" terminal on this amp. Check the inside too. Sometimes they jumper it there.
If there is no jumper, some other part has shorted to ground. Suspect C209 first. The 2 uf 25 volt electrolytic. R4 is a wire wound resistor with a variable tap for setting the bias. It doesn't have much range because the bias voltage is somewhat low in this amp. That is of particular concern if you are using Svetlana 572B tubes. Let me know if you have these tubes?
Pull up a schematic online for the amp and restore the wiring exactly the way it was. Make absolutely sure there is no jumper on the back 4 screw terminals causing it to stay keyed. It is the "RY" and either "E" terminal on this amp. Check the inside too. Sometimes they jumper it there.
If there is no jumper, some other part has shorted to ground. Suspect C209 first. The 2 uf 25 volt electrolytic. R4 is a wire wound resistor with a variable tap for setting the bias. It doesn't have much range because the bias voltage is somewhat low in this amp. That is of particular concern if you are using Svetlana 572B tubes. Let me know if you have these tubes?
Yeasu stays keyed
Shockwave I believe you are on the right track about having to do with bias part of amp and when I rewired relay amp was actually still on tube wise with relay on or off and did just cause another problem. This is a little more than I can handle right now so we just sold amp. We did tell next owner about problems but he said he was a tech and could fix amp so no problem there. I believe in honesty its just how we roll but I want to thank you all for the time and information you gave me for sure. Thanks Jimbo165
Shockwave I believe you are on the right track about having to do with bias part of amp and when I rewired relay amp was actually still on tube wise with relay on or off and did just cause another problem. This is a little more than I can handle right now so we just sold amp. We did tell next owner about problems but he said he was a tech and could fix amp so no problem there. I believe in honesty its just how we roll but I want to thank you all for the time and information you gave me for sure. Thanks Jimbo165
- No one is chatting at the moment.