Muting 1155 when on transmit
 

Hi Folks, can anyone explain to me how (if) the 1155 is muted when the 1154 is transmitting.

Pin numbers of connectors and functions would be useful.

I see there are 2, 220v Ht supplies to the 55. These appear to be labeled HT and HT (roty) ?
What are these lise for, one appears to go via the J switch.

Thanks, Ed

Re: Muting 1155 when on transmit
 

Hi Ed.
The aerial and phones connections are switched by the relay in the 1154 which as far as I can see is the only provision for muting the 1155. I think the second HT connection must be for the DF circuitry but I haven't looked at that closely.
Don m5aky

Re: Muting 1155 when on transmit
 

HT roty possibly means rotary converter.

Re: Muting 1155 when on transmit
 

Ed, do you have AP2548A? If not it can be downloaded from the VMARS archive, documents 1257 and 1677.
Figure 3 in the transmitter section shows the Keying Relay connections, contact A3 earths the receiver aerial input when the key is pressed. (Note that the key is the only way of switching between Send and Receive in a 'correctly' wired T1154/R1155 installation. So if operating in R/T (voice), the key must first be pressed to switch to Send).

Andy

Re: Muting 1155 when on transmit
 

Hi Gents, thanks for your thoughts.
I thought Roty meant rotary convertor, but I believe it only went to the set front end, so more likely muting?
The Rx aerial earthing makes more sense.

More study of the circuity needed

Cheers, Ed

Re: Muting 1155 when on transmit
 

https://vk2bv.org/archive/radio/r1155-files/charte.jpg

Lawrence.

Re: Muting 1155 when on transmit
 

Hi Lawrence, a very useful diagram.

Many thanks, Ed

Re: Muting 1155 when on transmit
 

The actual switch contacts on the RH wafer aren't shown very clear in that diagram and might confuse at first, here's a link to a clearer drawing of the wafers and what's what for the function selected:

http://www.vmarsmanuals.co.uk/t1154/fig8.pdf

Lawrence.

Re: Muting 1155 when on transmit
 

Mine works in reverse got some reason. The omni setting should mute the rx on TX, in fact it mutes the rx on key UP and opens it on key DOWN. Not entirely useful but I can't fathom a cause or a fix

Re: Muting 1155 when on transmit
 

Going through the interconnect and J switch wiring that initially looks very confusing, it would appear that the REC HT + is for the DF circuitry and at same time locks out TX HT in DF position. Rx mute is done by relay in 1154 on phones.

Very crude!, good job valve front ends are pretty well bomb proof (ouch!).
Andy

Re: Muting 1155 when on transmit
 

The receivers antenna inputs are also grounded by the transmitters keying relay when transmitting so far as I can make out.

Lawrence.

Re: Muting 1155 when on transmit
 

As I said above, contact A3 on the keying relay grounds the receiver aerial input when the key is pressed.

Andy

Re: Muting 1155 when on transmit
 

Yes, I was basically repeating what you said just in case anyone missed it.

Here's the link for showing the keying relay contacts in particular and the T1154 schematic etc etc:

http://www.vmarsmanuals.co.uk/t1154/para1-49.pdf

I never had the full set up, just the receiver (unmodified apart from the DF valves missing) and a homebrew PSU, it worked very well and powered a loudspeaker via a bog standard output transformer which was ok for me.

The first one I owned a long long time ago had the usual go faster mods etc.

Lawrence.

Re: Muting 1155 when on transmit
 

It was standard practice in service to remove the three DF valves if the DF function was not required, to reduce current drain. However I've never found an official instruction saying what should be done with the top-cap leads which would now be hanging free!

Andy

Re: Muting 1155 when on transmit
 

The DF section was all there except the valves, their TC connectors had been snipped so far as I can remember but non of the other DF bits had been ripped out to make way for a PSU or audio power output valve etc etc, at one point I was considering getting the DF valves but the price of the BL63 put me off, the tuning drive was a bit spasmodic when I got it but a quick trim of the cork and a clean up sorted that out.

Photo of said receiver below (ali case)

Lawrence.

Re: Muting 1155 when on transmit
 

It actually work very well. The receiver's magic eye can be used for approximate netting in transmit.

Re: Muting 1155 when on transmit
 

I acquired a couple of R1155s where the DF section was more or less intact, though the valves were missing. I just made a purpose-wired octal-to-octal converter (including wire for top cap) so that I could use a 6SN7 in place of the BL63 dual triode. The DF works very nicely.