Hi George, I was wondering, do you have plate current when the output dies? Is the plate current steady (ie; doesn't drop or rise) when the transmit power stops? If it was a relay dropping out, you would most likely here it dropping. You might just have a loose or cold solder joint in the RF output stage or driver circuit. But if the driver were dropping out, then the plate current would drop to the BIAS setting, or plate current resting point. I would start by setting it up into a dummy load and let it transmit (at very reduced power) until it quits, making sure not to exceed the duty cycle limit of the transmitter and when it quits, tap around the driver and RF cage with a non conducting (Maybe plastic) tool until you either determine that nothing is loose or find something loose and just repair it. You might also find that all is tight, and then you need to determine where you are loosing signal, in the driver stages or in the final output stage. When you have isolated the stage that the signal disappears in, then start the process of trouble shooting that stage. You could have a thermal problem with a component in the offending stage. Hope this helps you. If I was a betting man, I would bet the problem is in one of the driver stages, because if you had any of the problems I just suggested in the final stage, you would most likely have physical indications such as arching and smoke.
73, Mike - K7OV -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of George KB2Z Sent: Sunday, January 25, 2004 12:11 PM To: [EMAIL PROTECTED] Subject: [drakelist] T-4x Output Dies Intermittently Good afternoon all; Thanks for the reply's to my CW question. Got new tubes. Put them in and neutralized, abt 150W into a dummy load on 40M. Was working fine abt 5 minutes. The tx looses the output. It just dies. It seems like it happens after it warms up. The day I got it I was l tx-ing into a dummy load and it stopped. No output thru internal or external watt meter All seems normal, load, dip etc. Just no output power. Works intermittantly with either of 2 sets of tubes. To day I put in the new tubes and neut. them was getting 150W out on 40M. Started tx-ing into a dummy load and kaput, no output. Have you heard of an intermittent tx problem like this? (relay maybe?) If the power is not going out I cant figure where its going? Dip at 100ma. I figure without loading to high I should have some output at that level. Let it cool down few hours and tried it again. No good I have a feeling this excellent working tx got shook a little hard by UPS. Thanks for any suggestions, George KB2Z ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] - subscribe drakelist in body Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ----------------------------------------------------------------------
