Roberts RT1 which has been dropped

[Old Sparky]

I have now replaced C6, C12, C13, & C18 with some improvement (c13, btw, is an 8uf electrolytic, not an 0.01uf as stated in the Trader Sheet 1557), but I still find that the Oscillator Trimmers C8 & C9 have to be screwed fully inwards to get the alignment anywhere near right. On LW if C10 were o/c or high capacitance this would be the result, but there is no fixed padder cap. on MW.

[Old Sparky]

Further to the above, I've now replaced the main smoothing capacitor (100uf 6v, which read something like 170uf on my cheapchinese tester, btw), with a modern 470u, 16v. capacitor. Checked the alignment, and all is now OK, except for the fact that on LW all I could receive was a weak signal from Five Live's 693kHz transmitter on 223kHz in approx. the correct position on the dial. This would have been at about 4PM this afternoon, so presumably 198Khz was off the air. The RT1 is n my workshop, and I don't have a set here at home with LW on it, so cannot cofirm this, but don't know of any fault which would allow a weak signal to be received, yet not the usually very strong Radio 4 LW Transmission.

[Old Sparky]

Oops! Disregard the above. The fault is in the radio. A white lead from the w/c switch to the LW Osc. Padder Capacitor C10 had come adrift, whilst I was refitting the radio into it's cabinet (it's quite a tight fit). This of course reduced by 300pf - the value of said padder - the capacitance of the LW oscillator tuned circuit, thus raising the frequencies to which the LW band can be tuned. How it comes to be receiving a weak signal from Five Live on LW is a puzzle, though, unless the tuning is shifted to around 540kHz, unlikely methinks, but maybe what I'm hearing is 233kHz -i.e. the 693kHz transmitter via the L.O. tuning 470kz LF of the incoming signal

[Old Sparky]

With the white wire reconnecte normal operation has been restored, although Radio4 is still LF of it's correct dial position. The IFTs are tuned to the correct frequency (470kHz), and the MW tracking is as it should be. Reception of the main stations is good even in my cellar workshop, so I'll leave things be.

[Old Sparky]

               
The RT1 is now refitted to it's cabinet, which I had cleaned earlier. A replacement handle, albeit Black, is now fitted in place of the broken ends of the original Green one.  The only things to be sorted now, are the holes in the back cover, where someone had fitted a Car Aerial Socket and an extension speaker one, the latter simply wired in parallel with the internal speaker, plus the fact that the wooen strip on the inside of the back cover to which the hinge is attached is split to the extent that the screwa won't hold.  Ideally  I'd fit a replacement back cover, but cabinet parts for RT1s must be rarer than 'Hen's Teeth'!! Incidentally, although the RT1 was designed to use a no loger available 6v Battery (PP1 or PP11, IIRC) this one had a PP9 in it when it was brought to be, and seems quite happy to run on a 9v supply without any modification.