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Old 11th Apr 2021, 12:07 pm   #1
Colin Parry
Join Date: Apr 2021
Location: Yorkshire, UK.
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Default Trio 9R59DE alignment issue

I obtained one of these receivers some months ago. In excellent cosmetic condition, boxed and with the speaker (also boxed). Usual checks were carried out and over the last few weeks, capacitors have been replaced, a few resistors and a general internal clean up. Voltages seem about right (although slightly higher than in the service manual) and it appears fairly sensitive.

Final bit of work was an alignment. Everything went well and peaked up nicely, until I got to band D. The manual instructs you to peak up at 13mhz and then at 26mhz. Unfortunately, I cannot get band D to align properly. It will not track and becomes worse, the higher in frequency I go. By the time I get to 26mhz, the receiver is almost a full mhz out and there is not enough adjustment to bring it back to where it should be.

I have tried half a dozen times and always end up with the same issue. I have tried both sides of the oscillator frequency, but it seems to make no difference. Anyone got any ideas on where to go next? Thanks.
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Old 11th Apr 2021, 1:17 pm   #2
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Default Re: Trio 9R59DE alignment issue

Dont forget Colin.... the voltage readings will probably have been made with a lower Ohms / volt meter as in Avo 8 or similar.. If you are using a modern DVM or similar the voltages will read high, as there will be less loading on the circuit.
Should get out more.

Wendy G8BZY
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Old 11th Apr 2021, 2:03 pm   #3
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Default Re: Trio 9R59DE alignment issue

The service manual alignment instructions are shockingly bad. It doesn't tell you which side of RF the LO should be.

You will need some means to measure the oscillator frequency (second receiver, frequency counter or maybe a DSP dongle). If you establish the highest and lowest frequencies the LO can reach on range D maybe you can decide which it is.

Definitely get the oscillator tuning right and the dial reading correct before trying to align the RF. It does warn that there is pulling between them. If they mention it then it has to be pretty bad!

Good luck. I had a 9R59DS and I think LO was on high side of RF. That's why 14MHz Amateur Band always contained sprogs from the 15MHz BC Band. The LO was between them and the BC was on the image frequency.
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Old 11th Apr 2021, 4:53 pm   #4
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Default Re: Trio 9R59DE alignment issue

They had lots to say about the oscillator and mixer pulling in the 9R59DS.
Pity that again there is no mention of high side or low side injection.

The writer should have got an award! I never found any of that to be true.
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Old 12th Apr 2021, 1:16 am   #5
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Default Re: Trio 9R59DE alignment issue

AHA! I had the very same problem with a Heathkit "Mohican" that I bought from our local net auction site - not as a kitset but built up. It was a deaf as a post but a bit of sleuthing showed that all the voltages were about right. The coil pack was supposed to be pre-aligned but it all looked a bit strange with trimmers all at one end and the slugs likewise.

Anyway, I managed to blast a signal through the IF and that tuned up nicely in the end - ceramic filters probably led the original owner astray. Similarly I got signals through the low and eventually the high frequency bands BUT the highest band 20 to 32MHz just would not align nicely. Bearing in mind it was low side oscillator injection and 455kHz IF - the instructions showed how to determine if it is set up correctly by looking for the image frequency but the front end was so broad that it was very easy to lose where you were. Often you could get signals at both ends but be deaf in the middle! Then I found that if you did get everything right the oscillator would stop at around 26MHz!

I made a dummy plate to cover the underside of the coil pack which helped with that problem and another flash of inspiration led me to using a digital tranny radio to find the oscillator! Genius! It worked - but it was not possible to getting it to track right across the scale - of course there were two points on the inductor where the frequency was right at the low end but then the high end capacitance was too much or too little and the centre of the band was a meg or two out! Another inspirational flash and I made it track at about a quarter of the scale from each end as a compromise - then the RF stages would tune up nicely. I was happy to put up with that but it annoyed me that it wasn't as good as it should be.

Go back to the instructions. It says " to set up the bandspread capacitor, set the bandspread pointer to the left hand end of the scale and adjust the capacitor so that it is fully meshed - tighten the grub screw" but then "Check that the capacitor is nearly fully open when the pointer is on the "SET" position on the dial" - this is on the high frequency end of the bandspread dial. BUT "nearly" is not good enough! There was still a lot of capacitance left which meant that the trimmer could not be set low enough! I cheated and set the bandspread capacitor to almost the end of its minimum capacitance and then set the scale pointer onto the set mark. Bingo! Now everything fell into place and I could get good tuning at the high frequency end with the trimmer at half it's range. A few runs through at each end and carried out a tracking error check and it was all pretty good. Of course I had to re-align all the other bands now that the bandspread cap had slightly lower capacitance than before but I was happy at last! I celebrated with something cold and mildly alcoholic!
Cheers - Martin ZL2MC

Last edited by majoconz; 12th Apr 2021 at 1:29 am.
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Old 12th Apr 2021, 2:15 am   #6
Radio Wrangler
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Default Re: Trio 9R59DE alignment issue

A epic performance, Martin, but all too typical of the setup shenanigans of sets with bandspread.

Having the bandspread capacitor in the wrong position while trying to get the LO to agree with the main scale (with the correct IF offset of course) makes it an impossible task.

Using alignment frequencies about a quarter span in from each end is a way of compromising so you get as much alignment error swinging positive as you get swinging negative, and you get a better fit of your error curve. However, the dominance of the L setting at the LF point and the dominance of the C trimmer at the upper point are no as pronounced, so it takes more to and fro shuffles to get things as good as they can be.

I'm trying to remember if the 9R59 has double-tuned RF coils and that like IFTs there are two slug settings that give the right L and the right resonant frequency, one withthe two slugs closer together nd one with them further apart, peeping out of the other ends of their coils. The difference being in the coupling they give. With the slugs together you get a broad filter, M shaped rather than a narrow peak.

Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
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