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sobell1980 · 6th Oct 2014, 8:58 pm

Hi all,
I have now acquired a sig gen and oscillascope, and familiarised myself with both of them. I have injected an AF signal into the grid of the output valve and at the wiper contact of the volume pot and gained a good tone from the speaker. I have then switched to RF signal and injected a modulated 475 kc's into the grid of valve one. This again gave an identical tone to the AF signal injected earlier at the volume pot. I then worked back to C1. On the valve side of C1 i gain a good tone from the speaker, if i move to wave change side of C1, the tone becomes ever so slightly quieter. If i inject a signal at the aerial connections it is barely audible. C1 has been replaced. Signal generator tone through the speaker can be heard loud and clear in any wave change switch position. This is when the signal is injected the valve side of C1. It is very slightly quieter on the wave change switch side of C1 but only slight. Injecting into the mw frame aerial and LW aerial it can only just be heard. I guess it does need alignment, but something should be picked up on one of the wave bands. Even if faintly or some tuning whistles etc. I feel it could be the wave change switch seeing it is effecting all wave bands, not just one. Anyway this is my latest progress. Enjoying using the new kit if nothing else. Any pointers would be great and help. Feeling like i am gaining progress now.
Dave.

6th Oct 2014, 8:58 pm	#64
sobell1980 Octode Join Date: May 2011 Location: Bromyard, Herefordshire, UK. Posts: 1,241	Re: Roberts RMB Problems Hi all, I have now acquired a sig gen and oscillascope, and familiarised myself with both of them. I have injected an AF signal into the grid of the output valve and at the wiper contact of the volume pot and gained a good tone from the speaker. I have then switched to RF signal and injected a modulated 475 kc's into the grid of valve one. This again gave an identical tone to the AF signal injected earlier at the volume pot. I then worked back to C1. On the valve side of C1 i gain a good tone from the speaker, if i move to wave change side of C1, the tone becomes ever so slightly quieter. If i inject a signal at the aerial connections it is barely audible. C1 has been replaced. Signal generator tone through the speaker can be heard loud and clear in any wave change switch position. This is when the signal is injected the valve side of C1. It is very slightly quieter on the wave change switch side of C1 but only slight. Injecting into the mw frame aerial and LW aerial it can only just be heard. I guess it does need alignment, but something should be picked up on one of the wave bands. Even if faintly or some tuning whistles etc. I feel it could be the wave change switch seeing it is effecting all wave bands, not just one. Anyway this is my latest progress. Enjoying using the new kit if nothing else. Any pointers would be great and help. Feeling like i am gaining progress now. Dave.