Hello, Jim WB2FCN here. What you describe sounds like either of two things, in order to point you in the right direction. first let me say the bias supply, not only provides bias to the 250th but also to the grids of the 100th tubes and also to the 807s. This may sound strange but it works this way, when you set the bias on the 250th at -110V that sets the correct levels to the 807 tubes as well. The bias supply tube HAS to be a 5Z3 if it is an 80 the current draw exceeds the value for that tube and it flashes over or just quits working. So check the bias rectifier first is it correct is it on?
next if the unit is in cw mode, put the tune position switch in position and check the RF output, is it approximately 1/2 of the value you get in the mode causing you problems? Without turning on the HV turn on the oscillators, does the grid drive to the 250th go to around 70 MA? Also does the 0D3 regulator #1 glow if so then the unit is working properly up to the driver stages and all the regulators. A thought also is, has the unit been disassembled recently, if so check the harness cable to the RF deck and make sure the leads go to the proper terminals as if offset one way you have no ground from the modulator deck (bias supply) to the RF deck and it is seeking ground through some other path. If you could describe the model of BC-610, and what has been done to it, and how it is connected to your system ie is there a BC-614 or a JB-70 in your system. I might be able to pinpoint the problem from you symptomatic description. Give a holler. Jim WB2FCN http://eshop1.chem.buffalo.edu P.S. DO YOU HAVE A MANUAL? Jason Login wrote: > > > > --- Bob Login > --- [EMAIL PROTECTED] > > --- EarthLink: The #1 provider of the Real Internet. > > > Hi, > > Just spent the day working on a friends BC-610. The rig appears to be > > working but output is about 200W at 300ma but the 250th looks very yellow > > and bright glow as if its not tuned and radiating too much heat. I checked > the bias > > and found the required -110v but when the exciter is turned on the bias drops > to zero! > > I'm assuming that when keyed the bias also goes to zero and thats why the > final looks > > so hot and the output is low. If I take the rectifier from the exciter so > that there is no power > > to the exciter then the bias stays at -110v when the exciter switch is turned > to the on position. > > Why would the bias go off when the rig is keyed on? Any ideas would be > welcomed! > > Thanks and 73, Bob, AA8A > > --- StripMime Report -- processed MIME parts --- > text/html (html body -- converted) > The reason this message is shown is because the post was in HTML > or had an attachment. Attachments are not allowed. To learn how > to post in Plain-Text go to: http://www.expita.com/nomime.html --- > _______________________________________________ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
