19 set caveats

[sapper740]

Just received via UPS a WS19 MkII and, of course, I'm interested in getting it operational. It's missing the dogbone, ariel, microphone and headset and a lot of other bits. It's going to be a process, like everything else we sufferers of the Green Disease get involved in, but a worthy one. The first thing I assume I should check would be the dynamotor. Are there any 19 Set experts on MLU who could tell me if it's safe, and the proper procedure to energize the power supply and thence the radio itself? I've heard stories of exploding valves and jolts to the cranium from ungrounded sets. Any info greatly appreciated. Chimo! Derek.

[Mike Kelly]

Derek

yes you can fire it up and recieve ... I was doing the same as you 25 years ago.

There are high voltages flying around that can bite you but if you are sensible than its nothing to worry about.

The most important thing is to check the state of the capacitors .. over time they tend to dry out and shorts result. A quick check.. use a 12v supply and a ammeter in series and touch the HT input pins on the front socket .. against ground ... if there are any shorted caps the ammeter will show the leakage. A light globe will do it also.. if it lights up.. you have leaky caps. Dont put any higher voltage through it until you know the caps are OK .. it will blow the HT fuse in the PSU front panel if caps leak . Its worth replacing the caps anyway ... old ones can short anytime and new ones will last years.

The genemotors are bullet proof .. oil the bearings and check the filter caps in it.

I've owned about ten of them... from a design point of view, they tried to cram too much onto one chassis .. making the set a very awkard maintenance nightmare....

Mike

[Mike Kelly]

More tips

Clean all of the connections: pull the tubes out and spray a bit of electrical cleaner on the pins.. push em in and out a few times. The conical shaped rubber snap connectors are notoriously bad.. you need to clean the little tags each side for a good connection... generally clean anything that moves for a clean electrical connection. The tubes usually are in good shape .. they are common types and easy to find.. I had gobs of them ...new ones in packets.

The little VHF B set on the left is best left alone .. you wont hear anything from it anyway. On the A set you will hear short wave and hams... but the coarse tuning is not the best. You need to switch over to the CW position to hear SSB and morse... a long wire antenna is fine . The variometer isn't necessary for a station setup, it electrically increases the length of the whip antenna.. so the set thinks its looking at a low impedance .

Mike

[Bruce MacMillan]

Mike's reference to capacitors goes for just about any old tube (valve) radio. They usually are the weakest link if the radio has been sitting for a long time.

Definitely clean and re-lube the bearings on the dynamotor. There has been some discussion on one of the 19 set groups about not running the power supply without a load. Most REMEs and rad techs would apply a low voltage and gradually increase it to "form" the capacitors. This allows the chemicals inside to slowly become "normal". If you can't do that, as a sapper with EOD experience you should have no problem

I've seen photos of a catastrophic failure of C42, the receiver power supply filter cap. It looked like a destruct charge went off.

I've just finished a MKII and power supply for Mac's WC and didn't have to do any repairs to the radio itself. In fact most of the units have been very reliable after 65 years.

[David Dunlop]

Hello Derek.

I suggest you perform a close visual inspection of all the wiring and soldered connections before applying any power to the set. Particularly, if the bottom cover plate is missing from the set itself. There should also be a small metal cover over the top of the B-Set chassis. If any of the original military wiring has been changed, it will stick out like a sore thumb as most civilians who tinker with 19-Sets rarely bother to match the original loom on the wiring. Also, over time, the soldered connections take on a recognizable aged patina and the original factory workers did some very neat work. Recent work on the solder will typically be very shiny and sloppy. Also look for any signs wire cutters have been at work "collecting spares for a project".

Repairs and mods done by the military were usually well documented for each set and power supply unit. A small metal card holder would be fastened to the inside of the chassis and a card inserted in it that identified what changes were made and when performed. Sometimes the card goes missing after 60 odd years and all one finds is the empty metal holder, but that at least tells you the military did some appropriate work on the unit at some point in it's service life.

Only other suggestion I have would be to give the entire chassis a good dusting. A cheap set of ladies makeup brushes work very well for this kind of thing. It does not take that much dust to have excess heat build up in old electronic components and if humidity levels get high in your part of the world, enough dust buildup can result in some of the higher voltages in the set arcing to ground and frying the circuit. A lot of CRT televisions have died that way over the years.

Other than that, enjoy the project!

Best regards,

David

[sapper740]

Thank you all for the response to my question. My initial visual inspection shows this set appears to not have been tampered with. There are no notes inside the set detailing any servicing and the leads and loom appear to have the original varnish cambric. I'll do as you suggested and clean the set, test the capacitors, grease the dynamotor and see if it fires up. I seem to remember a quote about proper radios having a hiss, crackle and faint smell of ozone...hopefully mine doesn't emit a snap, boom and a strong odour of burnt insulation when I first power it up. Texas is known for it's high humidity in the summer, which lasts about 9 months of the year so I think this radio will have to be stored inside the house as my garage has no A/C. My wife is going to love this! Derek.

[JTH]

All old radios are run by smoke! Don't believe it? Just let the smoke out and see if it still works!


Jeff

[sapper740]

Well, I've fired up the rotary transformer after bypassing the "On" switch which remains open (one more thing I have to acquire) with no drama. The no-load output when running off a brand new 12 volt auto battery is 550 VDC which I assume is within parameters. I've joined the 19set forum and have received some invaluable information regarding running a modified MkII set with a single rotary transfomer and will be making a couple of modifications. I'm continuing to look for the "peripherals" and will keep all y'all informed of my progress. Thanks to Bruce MacMillan for offering to mail me the additional high tension brush I need. Derek.

[JTH]

Derek

When you get a list of wants, let me know, I have a pile of 19 set equipment and complete radio's. I need to let you know up front that I paid a fair amount for the sets and equipment and more to pick it up and bring it home (one way airfare and a 2 1/2 day drive with a full 2 ton rental van), so I am looking for fair value for the parts. I will not rip anyone off, but by the time I get rid of my surplus stuff I need to have offset my costs. However to me fair value also means good trades and I am looking for Universal carrier parts (armour mostly).

In any event let me know and perhaps we can work something out.

Jeff

[sapper740]

Thanks for the offer Jeff, it's one I might have to take you up on. I'll be tinkering with the 19 set off and on, it's not a priority so it'll be a long term project. Restoring a CMP, a 19 set, WWII reenacting, militaria collecting, mortgage and truck payment all on an Electrician's wages forces me to seek out the best deal on anything I buy so please don't be insulted by any offer I make on anything you have, it's not me talking, it's my bank account! Derek.

[JTH]

I hear you. Same reason I mentioned the background. She who must be obeyed said "you better get some money back on all that junk". They simply have no sense of history!!!

J

[sapper740]

Originally Posted by JTH

I hear you. Same reason I mentioned the background. She who must be obeyed said "you better get some money back on all that junk". They simply have no sense of history!!!

J

Jeff, do you have a 6 point to 6 point dogbone for sale?

[JTH]

I do. I sent yo a PM