EB5AGV's Eddystone 830 page

Eddystone 830/7 once cleaned Eddystone 830/7

Welcome to the Eddystone 830 page. I got this nice receiver as a Christmas gift and was my first tubed Eddystone. Here you have my comments about its restoration and different problems I found while restoring it. Note that REMARKS are written later and reflect current information or comments. I will add more information when I do the alignment. If you want to contribute anything, please, feel free to send me a message. Thanks!

Eddystone 830/7 Repair Notes


Yesterday I picked up an 830. I have good and not so good news. I found it was an 830/7 model and front panel was about an 8. Nice!.

REMARK: here you have some pictures of the set as I got it. As you can see, there was plenty of dirt... compare with pictures once it was cleaned, later in this document!

Eddystone 830/7 as received Eddystone 830/7 as received

Mc dial detail Mc dial detail

kc dial detail kc dial detail

So I took it home... to find somebody had badly butchered it :-(. It seems power transformer 6.3VAC winding was shot, so there were some wiring mods, not neatly done, to take filament power form two 3.15V outputs in the transformer (REMARK: later I discovered that this is the usual way 830s are wired and that there are two secondary windings in the power transformer which are not used, for 5 and 6.3VAC. But, anyway, what was true is that the filament wiring was changed, as it consists in two different 6.3 VAC windings and one of them was now not connected). Then, in most of the tubes, it was evident (poor soldering job) a wiring change. And that included some added components. Also, the noise limiter / AGC switch wafer was just missing, and some of its wires poorly soldered and the others just cut. Power cord was also replaced in a loosely way. There were also some missing covers. All in all, 'just a pretty face' :-(

I have the chance to pick up the other 830 in the pile... I know it is cosmetically worse (at least front panel wise). And it is probably an 830/2 (REMARK: it was really an 830/5, which is very close to the 830/7, but it was really in far worse shape) (it has an slightly different color scheme). But if it is in better condition internally, I will take it, as fixing the other one seems as a big challenge and some things just could not be fixed reasonably (as some charred wires, due to the lousy soldering job). I will let you know what I find. In case the other 830 is also in bad shape, I will go for the Electra.

Well, sometimes things are not as nice as they look at first glance. But, anyway, I am lucky to be able to select which receiver I want, checking it at home and then deciding. Imagine if you buy a rig overseas and, once you get it, you discover it is as the 830/7 I got...

BTW, in the pile (NOT available for me to have) there are some other interesting receivers, as a Marconi Nebula (about a 9 cosmetically) and Apollo (about an 8). Also an ITT-Mackay 3010C (in great shape). And older Eddystones, a Redifon R-50M, ... I can take any of them home and use it for some days if I wish... Perhaps some day, once I get my 'gift' receiver.

REMARK: as you can see, first impression I got from the 830/7 was really bad. But I am not easy to convince a set is not worth the time to fix it... so I finally decided to keep it and try to get it back to life!


Yesterday I had some time to work on my 830/7 project. I removed most parts of the mixer assembly (difficult task, as it is enclosed in a die cast aluminum chassis, with very limited access to some parts), as it had been rewired and I wanted to restore original circuit. It seems that a wire got loosen from a difficult to access wafer connection, and somebody decided it was better to rewire than disassemble. I understand why, as it took lots of hours!.

bottom view; rewired part circled bottom view; rewired part circled

band switch rewired wafer band switch rewired wafer

dismantled band switch dismantled band switch

But now the switch is rewired as it should and, once there, I replaced some charred wires (which were burnt when the rewiring was done) and routed conveniently some other missplaced wires. Another missing thing was the ANL/AVC switch wafer, which I replaced.

missing ANL/AVC switch wafer missing ANL/AVC switch wafer

And then I look at the poor job done to rewire the filament power wiring. I changed some wires, re-routed some others and added fasteners so the wiring looks good, although it is not original.

Then I took out all the valves (remember, this is a british set ;-) ) and checked them in my TV-7C/U. All except RF amplifier (V1) showed good readings, so I replaced V1 and connected the set. After a while I got some random 'cracking' noise from the speaker, no received nor calibrator signals. But tapping in some chassis parts I got a loud 'pop' at the speaker. So I started to look for loose contacts or bad soldering joints, armed with a plastic stick. I discovered a couple of 'obvious' faults: a coax shield which shorted another connection in a wafer switch and a resistor which had never been soldered; it was just touching at one end!. This set was manufactured around 1969, so it had been that way for no less than 32 years... Fixing both things removed the loud 'pop' when tapping the set, but the random noise continued same way. I suspected of a 0A2 voltage regulator (it uses two), as the noise was the same with the AF gain at minimum, but replacing them did not fix it. It was too late (00:30) so I let it for next day.

I will continue troubleshooting the set, from the speaker to the IF and RF sections, injecting signals, until I locate the (first) faulty stage. BTW, AF amplifier seems to work fine, as it produces the usual buzzing when touched with a screwdriver. But there is an obvious fault, as the S-meter is almost fixed in the upper part of the scale and RF/IF gain just barely move it.


Well, I am not yet finished with the receiver (it still needs some cleaning, specially on its dial, front panel and knobs and perhaps an alignment), but I have got the receiver working in all its nine bands. And, by the way, it seems pretty stable and sounds really fine :-)!

I had checked output stage with a signal generator and it worked fine. But previous stage, a 100kHz IF strip, was just not working. It is a two 6BA6 tube stage and injecting signal in the grid of any of them generated no output on their respective plates... so something was wrong. I checked same way the IF transformers to find they were fine. So I measured voltages at different tube pins to find that cathode voltage was, by far, too high (around 160VDC)...

What did I to get the rig working?. Well, thanks to Dave MW1DUJ, who sent me an scanned copy of the schematics, I found that the set has a MUTE condition which should be disabled by shorting two pins in a multiple connector on the rear of the set. It is same connector used for the speaker / line outputs. Of course, I did not get such connector with the set so I had temporarily connected the speaker directly by means of a coax cable to the back (internal side) of the connector, at its 3.2 Ohm position. But had no clue there was a MUTE which needed to be disabled :-)!

Once I got the receiver working, I dealt with the 'cracking noise'. Some of you suggested a bad capacitor to be the culprit of the noise. As the noise was the same at all AF gain settings, I began troubleshooting with my trusty Tektronix 475 oscilloscope, from the output tube to previous stages. Of course, the crackings could be seen at the plate of the 6AQ5 output tube. But they were also at the input grid. So they were also at the 6AT6 detector tube plate but not at any of its input pins. So something was not right at the 6AT6 plate circuit!. There were just three 'suspect' components: a coupling cap, a bypass cap and a resistor (connected to B+). I disconnected the bypass cap and the noise was still there. Then I lifted the coupling cap (which went to the 6AQ5 input grid) and the noise was not gone. So there was just one component which could be the culprit, a 270k Ohm resistor to B+!. I lifted one leg and it read open circuit with my Fluke 77... suspecting!. So I put another 270k resistor and connected the receiver... and the cracking noise was gone. Hooray!!!. As the old 270k resistor was still coneected at one side, I put the DVM on its lifted leg to read a non-stable voltage, from about 1 to 4 VDC... the cracking noise, for sure.

So this is the current status of the Eddystone 830/7 project. Now I just need to carefully clean it and, once I get a manual, check its alignment. So far I have found that all the works I had previously done (rewiring a butchered band switch wafer, replacing the AGC/NL wafer, resoldering loose connections, rewiring filament power cabling, replacing a weak RF amplifier tube, ...) were fine and everything is now working as expected. By the way, the butchered band switch wafer, in its standard condition, just bypass the 'band spread' function in lower three bands. I have found that it works fine as it should, bypassing it, as the dial has enough size to deal with lower bands without band spread. And, anyway, this is the original condition of the set, as it should be ;-)

I will probably do some extra work to let the filament wiring as it was originally. There is one tube, the VFO, which uses a completely different filament wiring, directly form the main transformer. All the other tubes share another filament wiring. I don't know why, somebody changed this and put the VFO tube filament in parallel with all the other tubes...

Now some pictures!

Cosmetic works on the receiver:

main dial and knobs removed main dial and knobs removed

kc dial mechanism kc dial mechanism

front panel (left) front panel (left)

front panel (right) front panel (right)

Here you have some pictures of the current looking of the receiver:

Eddystone 830/7 Eddystone 830/7

S-meter detail S-meter detail

kc dial detail kc dial detail

kc dial detail kc dial detail

Mc dial detail Mc dial detail

By now, this is the end of the story... I will add more information if I work more on the rig. Thanks for reading!

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