Hello Garey, all I went back to basics on this and checked out the power board. On Pin 21 of the power supply board I am measuring 22.6 Volts, when according to the schematic it should be +26v DC Reg Out. (This was after setting the 10 Volt Regulated supply with R2103).
The core of the inverter transformer (T2101) was damaged when I acquired the TR7. It had a chip that had broken off the corner piece. I managed to glue the core back together, and I thought it had worked. I also left off the white piece of wire that was wrapped around the original core. I guess I'll need to order a new core from the chap on eBay, but in the mean time can you confirm that this white piece of wire which was wrapped around the core, yet is not connected to anything, does anything electrical ? Once I have the supply stable, I'll start again. Thanks all, the diagrams sent off list are much better than the copy I was strauggling with. Best Regards Adrian MW1LCR -----Original Message----- From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net] On Behalf Of Garey Barrell Sent: 27 January 2010 18:28 To: Drakelist Subject: Re: [Drakelist] TR7 Re-alignmnet Adrian - Just a guess, but is your counter sensitive enough to measure the 8.05 MHz signal, it's only about 0.1V p-p. It's unlikely that the oscillator is wandering that much if it's running at all. Are you sure you're not in AM mode? The BFO has to be ON. It's also possible that your counter has a low impedance input and is loading the oscillator down too much. 32 MHz output in the 28 MHz position indicates an unlocked VCO. The first thing to check is the +24V DC supply line. If this voltage is low, the VCOs will lock on the lower bands in it's range, i.e., 21 MHz, but not the higher, 28 MHz band. If this voltage is low, check the core on DC-DC converter on the Power Supply board to be sure it's present, and tight. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs <www.k4oah.com> Adrian Rees wrote: > Hello all > > I am trying to re-align my TR7. So far I have followed the Service > Manual and am now trying to align the 8.05MHz Oscillator. (Section 3-5 > in the Service Manual). > > I can't seem to measure a stable output on pin 40. It seems to be > wandering around between 2 and 7 MHz. Additionaly on the 28MHz setting > the display is showing 32MHz, which I guess is the VCO. > > Should I fault find the VCO problem first or the 8.05MHz Oscillator. > Any help gratefully received ! > > Thanks > > Adrian MW1LCR > > > > _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
