Re: [Drakelist] 34PNB?
noise blankers that are 'plug-in' for collins are made by Wynn Works. Perhaps they can be modified for the Drake. David Goncalves W1EUJ On Sat, Jan 23, 2010 at 11:33 AM, Curt Nixon wrote: > Is there a source for boards / cloning info for the 34PNB Noise Blanker for > the TR4? > > If not, is there any interest in having boards made up? > > Curt > KU8L > > ___ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > -- David Goncalves ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T4XB No +250V AND blown Filament Fuse
OK and thanks to all. I just got back home and am going to try the T4Xb troubleshooting again this weekend. Will pull the finals and see if that is what is pulling the 250 B+ down. The R3 was in the AC4 sorry for not noting this before. I looked at the old one and the schematic and was reading it as 1k but will look again and make sure it I have the value correct. Auto parts store had some 10amp glass buss fuses in packs of 5 so I got one for the fil fuse 8A and will at least replace the #22 wire I put in there before I do any more. The filaments are lighting ok with the wire in at this point. 73, Paul -- Paul Gerhardt K3PG http://pgerhardt.blogspot.com QRP ARCI 6674 FP 274 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] T-4XC Bias
Have good bias (-55 adjustable up - or down - to -75V) at rear plug - and on PS sub board, but nothing getting to finals - any good ideas where to look first? Michael W7HUT ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T4XB No +250V AND blown Filament Fuse
Paul - Couple of things. One, be careful using a larger fuse than the 8 Amp original. That fuse is to protect the wiring harness in case of a filament short. Melted harness = parts radio. The early units used a piece of #30 wire instead of a fuse. There aren't many places in the transmitter where enough current can be drawn from the +250 bus to heat up R3 in the AC-4 without smoking something IN the radio itself. I believe I'd start with V7, as a short here would put R35 across the +250 bus for approximately a 4.5 W load. Of course a short anywhere along the +150 bus would give a similar result, but all but the PTO/BAND OSC resistor paths are small, high value resistors So... Guessing shorted VR tube, V7 socket wiring shorted, shorted lead to PTO. Let us know! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs Paul Gerhardt wrote: OK and thanks to all. I just got back home and am going to try the T4Xb troubleshooting again this weekend. Will pull the finals and see if that is what is pulling the 250 B+ down. The R3 was in the AC4 sorry for not noting this before. I looked at the old one and the schematic and was reading it as 1k but will look again and make sure it I have the value correct. Auto parts store had some 10amp glass buss fuses in packs of 5 so I got one for the fil fuse 8A and will at least replace the #22 wire I put in there before I do any more. The filaments are lighting ok with the wire in at this point. 73, Paul ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T-4XC Bias
Michael - Shorted V1, shorted C63. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs Michael Ditmore wrote: Have good bias (-55 adjustable up - or down - to -75V) at rear plug - and on PS sub board, but nothing getting to finals - any good ideas where to look first? Michael W7HUT ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T4XB No +250V AND blown Filament Fuse
Paul - I realized I used the wrong number for the "fuse" wire. I actually use a single strand of 18-2 ZIP cord, which I think is #33. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs Paul Gerhardt wrote: OK and thanks to all. I just got back home and am going to try the T4Xb troubleshooting again this weekend. Will pull the finals and see if that is what is pulling the 250 B+ down. The R3 was in the AC4 sorry for not noting this before. I looked at the old one and the schematic and was reading it as 1k but will look again and make sure it I have the value correct. Auto parts store had some 10amp glass buss fuses in packs of 5 so I got one for the fil fuse 8A and will at least replace the #22 wire I put in there before I do any more. The filaments are lighting ok with the wire in at this point. 73, Paul ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R-4C Audio Problem
I have an interesting problem to present to the group. I'm in the process of restoring a later model R-4C that has a peculiar audio problem. The receiver is working fine with excellent sensitivity on all bands, except that on 80m when I turn on the crystal calibrator, I hear what appear to be weak, but very raspy spurious birdies in between the 25 KHz markers. When I vary the volume control, the birdies sweep through the passband of the receiver. Also, when listening to the audio output with a pair of headphones when the receiver is muted, I hear the usual low level hum that is typical for the R-4C, but it changes characteristics over a relatively small range around the 9 o'clock position of the volume control. The hum does not change in volume, it just sounds rather raspy over this small range, similar in characteristic to the birdies I hear in between the 25 KHz markers. Is it possible the audio output stage is self oscillating at some odd frequency and is somehow mixing with or modulating the output of the crystal calibrator? I don't have access to a scope, but I do have access to a good quality Fluke DVM and an IFR service monitor. I would appreciate any suggestions on where to start looking. This particular receiver was in storage for about 15 years, so I wouldn't be surprised if there are some electrolytic capacitor issues. Thanks in advance. 73 de Bill, K9RZ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
