R1155 model E (we think it's model E, certainly an R1155)

[Station X]

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[goodfortune]

Originally Posted by Station X

You can post up to five images in a post. If they are too large the forum software will resize them for you. but they may take a long time to upload.

Before submitting your post click on the "preview" button to make sure your images are there.

Graham, thank you so much. Chaps and ladies, be prepared for them to arrive twice...eventually!

I loaded four pictures I think but didn't click "preview". Each forum has its own peculiarities.

Once again thank you Graham, much appreciated.

Kind regards,

goodfortune

[AlanBeckett]

Pictures are sized automatically.
You probably didn't hit the Upload button or didn't wait long enough for them to upload.
Give it another go.
Alan

[goodfortune]

Pictures!

K r,

goodfortune

[Sean Williams]

Aha, not an original power supply - a home made one in a TU5 case......

[goodfortune]

Please do comment, I'd like to know more about these items. Thanks for your comments.

Kind regards,

goodfortune

[MichaelR]

As Sean has pointd out the power supply and by the looks of it an audio amplifier is in the second box and is not a Ministry item but a homemade unit.

It does looks as though the receiver has not been "butchered" , if you could take the case off and take some pictures of the inside we would have a better idea as to how complete it is.

If the receiver is complete and original even though the power supply is home brew the whole kit would be worth quite a lot of money on an auction site.

Mike

[M0FYA Andy]

As Sean says, the PSU is homebuilt in a Tuning Unit case, so it looks like I have lost my money!

There is still no good reason why the cases can't touch, unless the HT- is connected to the PSU case instead of floating.

Andy

[goodfortune]

Well, Andy, I certainly have no idea whatsoever!

This weekend I shall undertake to open the back if I can work out how and take some pictures. Possibly also the other box as I'm curious what this floating thing means and I'm positive you all will be able to enlighten me.

I really am grateful for your time and your comments.

goodfortune

[Sideband]

Originally Posted by goodfortune

I'm curious what this floating thing means

Ahh! 'Floating' is a bit of trade jargon. Normally the casing (especially if it's metal) is earthed for safety. If it isn't earthed and is not connected to anything else, it is said to be 'floating'. It can also apply to a lead or wire that is only connected at one end. If the casing of your power supply and the casing of the radio are at different potentials, they shouldn't be connected to each other and should be left 'floating' (not connected).


SB.

[goodfortune]

Originally Posted by Sideband

Ahh! 'Floating' is a bit of trade jargon. Normally the casing (especially if it's metal) is earthed for safety. If it isn't earthed and is not connected to anything else, it is said to be 'floating'. It can also apply to a lead or wire that is only connected at one end. If the casing of your power supply and the casing of the radio are at different potentials, they shouldn't be connected to each other and should be left 'floating' (not connected).


SB.

Oh, sideband, you have me laughing! And there was me thinking to myself "next time I try to move that box I must keep it level, there's something floating in there"!!!!!

goodfortune

[M0FYA Andy]

I’ll try to explain! In most radio receivers (other than AC/DC domestic types where the chassis is connected to one side of the mains, but that is another story!), the negative side of the HT supply is connected to the chassis, which is also earthed. Therefore, if the supply is installed in an external metal-cased unit powered from the mains, which requires the case to be earthed for safety reasons, the HT-ve can also be connected to the power supply case, as both the Rx and PSU cases are at the same potential.

However, the R1155 is unusual (but not unique) in that the HT-ve is not connected to the chassis. The attached diagram is taken from AP1186, and shows the bias arrangements. The important thing to note is the network of resistors connected between earth (chassis) and HT-ve. If these are inadvertently short-circuited by interconnecting HT-ve and chassis , then the biasing is totally upset.

For this reason the HT-ve should be ‘left floating’ in the PSU, that is, not connected to the chassis. This means, for example, that if one wants to use smoothing capacitors with the negative side connected to the metal can, precautions must be taken to isolate the can from the chassis.

I hope this makes things clearer!
Andy

[goodfortune]

I'm sorry Andy, I can't see that diagram, eyesight too poor I'm afraid, even zoomed!

I'm getting some of your explanation, (for example understand -ve = negative) but I don't know what HT means! However, websearch sites are marvelous, I'll get to the bottom of it!

Thank you,

goodfortune

[MichaelR]

Originally Posted by goodfortune

Well, Andy, I certainly have no idea whatsoever!

This weekend I shall undertake to open the back if I can work out how and take some pictures. Possibly also the other box as I'm curious what this floating thing means and I'm positive you all will be able to enlighten me.

I really am grateful for your time and your comments.

goodfortune

The R1155 is easy to remove from its case. On the front panel in each corner there is a screw , just unsrew these. With some care pull the receiver from its case usinrg the grab handles. ( you may need to get someone to hold the case at this point )

Mike

[M0FYA Andy]

Apologies, it's difficult to know what level of knowlege to start at!

You don't really need to see all the detail on the diagram - the important thing is that the vertical line down the middle shows all the things joined to the chassis, with the earth symbol at the bottom, and the vertical line on the right is the HT-ve. The critical point is that they are not connected directly together.

HT means High Tension, which is the couple of hundred volts DC required by the valve anodes. There is also the LT, Low Tension, for the valve heaters, in this case 6.3 volts.

(Then there is EHT, Extra High Tension, not relevant for this receiver, but I used this acronym in an earlier post to refer to the 1200v required by the T1154 transmitter, or it is used to refer to the high voltage needed by a cathode ray tube).

Andy

[dave walsh]

Andy means High Tension GF ie the 200 volts + on the valves. This reminds me of the difficulties with manuals written with the best intention but you can never be simple enough if someone is just not familiar with the topic. Thought I'd cracked it in post 14* but I was overconfident.
At least it's probaly worth a bit [and I also wouldn't rush to touch the cases together when it's plugged in ]. Out of interest, where does the Tuning Unit 5 case orignate from Sean? Not in a Lancaster I presume! I'm sure that I've got something similar [the TU] in Rammy.
Dave W

Crossover reply with the man himself!

[MichaelR]

Originally Posted by dave walsh

Out of interest, where does the Tuning Unit 5 case orignate from? Not in a Lancaster I presume! I'm sure that I've got something similar [the TU] in Rammy.
Dave W

Crossover reply with the man himself!

Dave,

The tuning unit referred to is for the BC191 transmitter , this had a series of units for the different bands ( similar to HRO concept ) which you slotted in place before switch on. I have a pristine original for 80 metres and is a fantastic example of US engineering. I think they were for ground use not airborne

Mike

[dave walsh]

Ok thanks Michael. I think my box is US but with a big coil and v condensor! Dave

[M0FYA Andy]

Dave,
The Tuning Units are used in the BC191 as said by Mike, and also the BC375. The BC191 and BC375 are the same apart from operating voltage. The BC191 valve heaters and relays are wired for 12v, whereas the BC375 requires 24v. The HT is derived from an external dynamotor unit available in 12 and 24v versions.
They certainly were for airborne use, in such US aircraft as the B17, in combination with the BC348 receiver. These were the US equivalent of the RAF T1154/R1155 combination in the Lancaster, and referred to as the Liason Set for long distance communication back to base. (In addition there was the Command Set, equivalent to the Lancaster's TR1196 or TR5043 for local communication between aircraft or for emergency use, but this is getting a bit off-topic!)

Andy

[goodfortune]

Fascinating stuff! And thank you gentlemen for explaining in a manner I could (roughly) understand!

I shall take the front off this weekend and post some pictures, as I'm very interested to know what's inside, myself!

I do hope you don't think I'm being purely mercenary. Even if we don't eventually sell the receiver and its power unit, I need to get a proper valuation for insurance purposes, I think. The receiver has been sitting within the "middle section" of a ceiling high wooden linen press (I think all the traditional 30s homes had them) in our lounge for many years now, and is at home there.

Have a good day,

goodfortune