Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Eddy -
OK. Well if it works in TUNE, then ALL the audio stages are working fine. In TUNE, the first mic preamp stage is switched to become a phase shift audio oscillator, and that tone then goes through the transmitter just as if you whistled into the microphone. That same tone is used for the sidetone, and to keep the PTT relay closed in CW. So this leaves a very narrow field for failures, i.e., a couple of switch contacts or the mic jack.
So... Either John is correct that your mic is bad, (D-104's are prone to failing from heat and/or humidity,) the wiring to the mic jack is wrong, or there is a problem with the switching between mic amp and TUNE oscillator.
You can check the mic with a scope, if you have one, if not, a VTVM or "good" DMM right at the cartridge terminals should show considerable (a volt or so) AC output when you whistle into the mic.
73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs <www.k4oah.com> EP Swynar wrote:
"EP Swynar" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- On 4th July, Garey wrote... "...If you have a KEY plugged in, it must be closed (or unplugged) for SSB..." *************************************** Hi Garey, Well, I was HOPING that the solution to my lack of audio on SSB / AM with the T-4X would have been that easy, but alas, there was no joy in Muddville (again) when I tried it here (double sigh!). I measured the resistances on both V9 & V10 afterward, & all appears to be normal in that regard...next I guess I'll have to measure the actual voltages themeselves. The rig fires up on CW splendidly: it tunes up just as outlined in the manual, has a nice side tone, mutes the R-4, etc. etc. Yet, when I switch to SSB, I CAN trip the internal relay by pressing the PTT button --- but I get only a VERY slight indication of plate current (NO output power) in the mode, and no upward kicks of the meter in any position when tapping the mic...even with the gain cranked way up. With the rig set to AM, the plate current DOES swing hard right momentarily when the PTT is first keyed, but I suspect that has something to do with the controlled carrier set-up in that mode. Back to the ol' proverbial drawing board for me, I guess...! ~73~ Eddy VE3CUI - VE3XZ
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