Marconi R1155 Alignment - UK Vintage Radio Repair and Restoration Discussion Forum

tinkera123 · 28th Jan 2022, 7:42 am

Hi all,

My R1155 is now functioning okay, but I intend to do an alignment of IF's, Osc, RF etc.. I can identify most 're-alignment' points ... except for the "IF primary slug" versus "IF secondary slug". I have not had to pull one of the IF cans apart as yet, hence I cannot identify which is which. Nothing in the Manuals I have give any guidance.

Within each IF can, there is a lower and an upper tuning slug. Can anyone advise as to which is the Primary and which is the Secondary??

Thanks,
Ian

HamishBoxer · 28th Jan 2022, 11:17 am

I think the upper is possibly primary, do you really need to align the set though? Normally if not been got at , they are fine and saves the problem of stuck/broken cores.

ms660 · 28th Jan 2022, 11:23 am

The lower slug will be the primary and the upper slug will be the secondary which makes sense if you think about where the grid lead comes out.

Lawrence.

tinkera123 · 30th Jan 2022, 3:16 am

Hi all,

Lawrence ... yes, I understand your reasoning here. If designing the IF Can from scratch, that is what I think an Engineer should do ... but I'm not an Engineer. I looked for logic of the connections of the anodes feeding the LC circuit to the Tag strip underneath in relation to the Top Cap connection, but found none (sample size only 2 ....

.. ).

Hamish ... I still might not align the IF ... I have struggled with broken Slugs in other radios ... not fun. I am sure that the Slugs in L21 are cracked (those in L19 and L20 and in rest of radio are okay). Hopefully, they were not moved when broken .... So, I will dig around in my junk stuff to see if I have any replacement Slugs. Also, I will have a look at the frequency(ies) and shape(s) of the IF strip.

Thanks,
Ian

ms660 · 30th Jan 2022, 10:53 am

Quote:

Originally Posted by tinkera123

Lawrence ... yes, I understand your reasoning here. If designing the IF Can from scratch, that is what I think an Engineer should do ... but I'm not an Engineer. I looked for logic of the connections of the anodes feeding the LC circuit to the Tag strip underneath in relation to the Top Cap connection, but found none (sample size only 2 ....

.. ).

Mag. page 3:

https://worldradiohistory.com/UK/Rad...in-1947-07.pdf

Lawrence.

tinkera123 · 30th Jan 2022, 12:23 pm

Lawrence ... you are a Legend. Many thanks.

ms660 · 30th Jan 2022, 12:26 pm

No problem.

Lawrence.

tinkera123 · 12th Feb 2022, 8:29 am

Hi all,
Re: Alignment of my R1155

Unfortunately, the tuning slugs in the 3rd IF Can (L21) cannot be moved. I had a look at the resonance profile of this Can and it is a good shape and quite sharp (peaky) a few kHz above the IF frequency of 560kHz.

As the tuning slugs in the other IF Cans can be moved, I decided to align the IF Strip to the L21 frequency. I also re-aligned the Oscillator, both RF circuits and BFO accordingly.

The radio is now quite responsive on the HF Bands and Broadcast Band. Many stations are audible on HF Bands after dark; most are from our northern neighbours and unintelligible to me. The lower frequency Bands aren't of interest.

I have a bit of tidying up to do, plus a list of improvements for the future, but for now, it will be my daily 'listener' on the Broadcast Band. I have other more sensitive Comms Receivers for HF stuff.

I had a problem understanding the interplay between Grid Bias and AVC circuits ... until I 'twigged' to the the AVC Delay. The Tuning Dial is fantastic, so easy to use.

Another one lives ....

Cheers, Ian

28th Jan 2022, 7:42 am	#1
tinkera123 Triode Join Date: Nov 2019 Location: Melbourne, Victoria, Australia Posts: 16	Marconi R1155 Alignment Hi all, My R1155 is now functioning okay, but I intend to do an alignment of IF's, Osc, RF etc.. I can identify most 're-alignment' points ... except for the "IF primary slug" versus "IF secondary slug". I have not had to pull one of the IF cans apart as yet, hence I cannot identify which is which. Nothing in the Manuals I have give any guidance. Within each IF can, there is a lower and an upper tuning slug. Can anyone advise as to which is the Primary and which is the Secondary?? Thanks, Ian

28th Jan 2022, 11:17 am	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Marconi R1155 Alignment I think the upper is possibly primary, do you really need to align the set though? Normally if not been got at , they are fine and saves the problem of stuck/broken cores. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

28th Jan 2022, 11:23 am	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Marconi R1155 Alignment The lower slug will be the primary and the upper slug will be the secondary which makes sense if you think about where the grid lead comes out. Lawrence.

30th Jan 2022, 3:16 am	#4
tinkera123 Triode Join Date: Nov 2019 Location: Melbourne, Victoria, Australia Posts: 16	Re: Marconi R1155 Alignment Hi all, Lawrence ... yes, I understand your reasoning here. If designing the IF Can from scratch, that is what I think an Engineer should do ... but I'm not an Engineer. I looked for logic of the connections of the anodes feeding the LC circuit to the Tag strip underneath in relation to the Top Cap connection, but found none (sample size only 2 .... .. ). Hamish ... I still might not align the IF ... I have struggled with broken Slugs in other radios ... not fun. I am sure that the Slugs in L21 are cracked (those in L19 and L20 and in rest of radio are okay). Hopefully, they were not moved when broken .... So, I will dig around in my junk stuff to see if I have any replacement Slugs. Also, I will have a look at the frequency(ies) and shape(s) of the IF strip. Thanks, Ian

30th Jan 2022, 12:23 pm	#6
tinkera123 Triode Join Date: Nov 2019 Location: Melbourne, Victoria, Australia Posts: 16	Re: Marconi R1155 Alignment Lawrence ... you are a Legend. Many thanks.

30th Jan 2022, 12:26 pm	#7
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Marconi R1155 Alignment No problem. Lawrence.

12th Feb 2022, 8:29 am	#8
tinkera123 Triode Join Date: Nov 2019 Location: Melbourne, Victoria, Australia Posts: 16	Re: Marconi R1155 Alignment Hi all, Re: Alignment of my R1155 Unfortunately, the tuning slugs in the 3rd IF Can (L21) cannot be moved. I had a look at the resonance profile of this Can and it is a good shape and quite sharp (peaky) a few kHz above the IF frequency of 560kHz. As the tuning slugs in the other IF Cans can be moved, I decided to align the IF Strip to the L21 frequency. I also re-aligned the Oscillator, both RF circuits and BFO accordingly. The radio is now quite responsive on the HF Bands and Broadcast Band. Many stations are audible on HF Bands after dark; most are from our northern neighbours and unintelligible to me. The lower frequency Bands aren't of interest. I have a bit of tidying up to do, plus a list of improvements for the future, but for now, it will be my daily 'listener' on the Broadcast Band. I have other more sensitive Comms Receivers for HF stuff. I had a problem understanding the interplay between Grid Bias and AVC circuits ... until I 'twigged' to the the AVC Delay. The Tuning Dial is fantastic, so easy to use. Another one lives .... Cheers, Ian