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Finally repaired my original TR-7 PBT board that I roasted the U1001 analog switch on. (Dieter was right!) Took about a month to get the IC via eBay/Asia. Unsoldering that dude took about two hours to get all the little pins out after I surrendered and used the "Wedge" method of chopping it out and unsoldering the pins afterward. Still pretty rough on the circuit traces. Because of this I dug through the junk box and put in a 14 pin DIP socket instead of directly soldering the IC in. I was very surprised that it came right up after I set the 13.695 VXCO. Boom. Not sure if there is a sweeter-sounding receiver when everything's dialed in. Next up: 1) The "better all-band transmit mod", 2) grounding mod to eliminate 40m parasitic, and 3) Cinch-Jones plug and fan mod to remove 120V from unit. Tip of the cap to you guys for helping me keep this relic on the air. -- Craig/W8CS Greenville, SC

Hi to all in the group! While having not fully finished repair work on the low-serial TR7 I posted about some while ago, an opportunity came up this weekend that I just could not turn down - a Drake TR4310 (HF) Communications Transceiver. When will I learn to finish one project prior to starting the next! The example I have acquired (2xx serial number) started life in Africa. Retired from commercial service, it was gifted to a UK amateur who happened to be passing through the country in the course of his employment. He sold it to me for a most agreeable price, in view of it having been in storage for some years, now not working and with some UK repair shop hinting it would be uneconomic to put right. The transceiver is dirty, but in good physical shape. It came with the full, paper service manual, which documents all of the differences between the TR4310 and TR7, on which it is firmly based. The parent board in it is stamped '5 May 1981', so around the time Drake was transitioning between making TR7 and TR7A. I've had the radio on the bench this afternoon. Annoyingly, I cannot find the small Allen key that will allow me to take the knob off the bandswitch (anyone know the size of this?). As a result, I am unable to hinge the front panel down and pull the display board and get to the boards underneath. I pulled all of the boards in the top-rear card cage and have cleaned all their Molex connectors, plus the relay contacts. The 4310 has all four filter slots filled as standard:-) Looks like there is an AUX7 board fitted, with maybe some band modules too:-) With no short circuit on the power input connector and internal fuse intact, I connected up an antenna and applied power. Sure enough it didn't work. Well, actually, quite a lot of it did! I have all voltage rails coming out of the power supply. The display has a few digits lit. Audio and RF gain controls are good. Mode, Filter and PBT functions change the noise in the speaker in the way you would expect. The calibrator produces drifty audio tones in the loudspeaker. Switching between bands and turning the Aux Program knob causes the 'set band' to illuminate and extinguish. On the negative side, there's no MHz digits displayed on the seven segment LED frequency readout for any band. Turning the knob on the (synthesised - yeah, like an RV75!) internal VFO causes some change to the last three right-hand digits, but does not look correct. I think the number one issue is lack of VHF local oscillator injection. I plugged in an RV7 external VFO and got no better results. I'm looking forward to getting this one going and will post updates to this thread once I get further down the line. One thing I am already enjoying is how much easier it seems to be to get to everything in the radio, compared to a TR7, especially the RF HPF and LPF assemblies (hope I will not have cause to go there). Should any other 4310 owners wish to chip in and share their experiences, please feel free. Regards, Mark.

I was about to make the "Better All Band Transmit Modification" to my TR-7A when I noticed that the digital control board is different: Is my best option now to use the traditional "cut the parent board trace" for pin 11 on the DCB? Thanks -- Craig/W8CS Greenville, SC

I am reminded that my stock of FT-243 and HC-6/U crystals on oddball frequencies is dwindling again. Here at AF4K Crystals, I use them for rebuilding onto useful frequencies. Does anyone have a stockpile of such vintage crystals? They look like this: FT-243 - May have a bakelite or metal front cover. HC-6/U Can only use the ones with a soldered seam. Both have pins spaced about 1/2 inch (0.486") Let me know what you have and we can discuss how I can get them here for reuse by current operators. Reuse is the best form of recycling, right? Thank you. Steve WD8DAS sbjohnston@... http://www.wd8das.net/ http://af4k-crystals.com/ -------------------------------------------------------------------- Radio is your best entertainment value. --------------------------------------------------------------------

These 1/2W resistors look original. I have yet to measure them but they don’t look cooked. There are a couple of other places where the repair soldering isn’t stellar but this rig right now is working on 80-15 with full (well, 100-150W) power and receive. I suspect that 10 needs an oscillator coil tweak. My question is re the resistors. Was this the original configuration? I’ve worked on very early T-4 and T-4X’s that have 1W cathode resistors. Also note the monolithic filter that was the originally used in the early sets — note there’s no cutout in the chassis so this is the first soupcan replacement. It’s a late summer 1966 build (23xxx). Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana. Sent from Proton Mail for iOS

Mark; You wrote...... "In the TR4310 I have here, and in the manual that came with it, there is definitely no PTO! The analogous function is provided by the VRTO synthesister, which has essentially the same circuitry as the somewhat rare Drake RV75 synthesised VFO, but a different mechanical layout to make it fit inside the '4310's case. Were there two versions (generations) of '4310 - one (early) with a PTO and the later (produced at the time of the TR7A) with VRTO? I do have a dim recollection of reading about a commercial / rack-mounting version of a TR7. The model 'TR43' rang a bell, but could not find any reference to it on www. (We found out a few months back that the TR4305 looked to be a fixed channel {crystal controlled} version of a TR5.)" Possibly..... though I have not been able to find out if the TR-77 and R-77 models produced for Radio Monaco had a true PTO (though with only a digital display) or if it had the VRTO tuning. There weren't very many made. I have seen pics of Radio Monaco with as many as six Drake rack-mounted stations, though one online reference to the TR-77 and R-77 says they only had four racks. Search YouTube to see Fernando's TR-77/R-77 station. I have never seen/heard of a "TR-43". Sindre could possibly shed some light on this topic. Sindre? 73 Peter VE7PS

I'm not the first to have done this, just reporting this to help if anyone is on the fence. I noticed some poor performance on my T-4XC that I pulled out of mothballs this year after a long siesta. Did the heathkit shop AC-4 upgrade, no difference in output, more of a preventative thing with 48 year old caps. Started poking around the finals section and noticed that the cathode resistors were 17.2 and 19.3 ohms, pretty out of spec for 15 ohm resistors. This week I got around to looking at the rest of the circuit including screen, screen supply, and meter shunt resistors. R49 2W 1.5Kohm was heat-swollen and running 1600 ohms R50/R51 screen resistors (68 ohm) were measuring 73/76 ohms R59 meter shunt resistor (3.3 ohm) was measuring 4.5 ohms Replaced all of these with upgraded/over-spec components and WOW what a difference. Easily hits 100W output on 10M, 150W+ on lower bands. No, I'm not going to run this unit at those numbers but nice to see the potential. And this is with what I consider to be "soft" final tubes. Also installed a couple of binding posts on the rear panel which pigtail across the meter shunt resistor for easier bias set/checks. I could post pictures of the mods if anyone is curious. -- Craig/W8CS Greenville, SC

I've been using one of the PLJ 6LED counter modules in an external housing for digital frequency readout for my R4C. I'd like to mount the display inside the existing dial window on the R4C, but the window isn't really wide enough to view all the digits. So, would like to modify the width of the window but would need a bezel to give it the desired finished look. I've searched the usual sources for an appropriate bezel, but haven't come up with anything that will fit properly. I wonder if anyone else has located one? 73, Floyd - K8AC