Trio 9R-59DS
 

Hi,
Guys, I need some help here!

I have just acquired a Trio 9R-59DS. On testing I found that MW AM was loud and clear. With a little teaking I got some volume from the shortwave bands on AM. However, on the amateur bands (USB or LSB) there is hardly any volume at all.

I have tweaked the IF coils on the top of the chassis for max signal strength.
That's where I've got to.

Is there anyone out there that knows this rig that can suggest the next steps I should try?

Best regards,

Malcolm
G4TJK

Re: Trio 9R-59DS
 

Hello Malcolm,

Assuming this is a fault and not just down to band conditions/aerial, a good place to start would be to check the voltages around the product detector valve (V6). The circuit diagram has them marked as:

Cathode (pin 2) 2.7V
Anode (pin 5) 150V
Screen (pin 6) 64V.

Any that are a long way off would suggest a component fault in that area.

Paula

Re: Trio 9R-59DS
 

https://www.manualslib.com/manual/12...o-9r-59de.html

Click on "Download" at the top of the page and pass the "I'm not a robot" test!

Hope it was only the IF transformer cores that you tweaked.

Re: Trio 9R-59DS
 

OK. An update.

I have completed the alignment process as per the Service Manual. Here is the situation now (starting with the IF):

- AM Reception is good, generally, although I notice that I lose signals on low frequencies of the bands - Band C, in particular. (Using my FT-991A to detect the LO I can see that the output level drops to zero as frequency is decreased. In the case of Band C, I suspect capacitor C103, 4000pF. Will investigate further.

- After working on the BFO I can receive and resolve sideband signals, but the audio volume level is VERY low.

Has anyone else seen these problems?

Best regards,

Malcolm G4TJK

Re: Trio 9R-59DS
 

Isn't this set a known one where degradation of the wax on the coils is responsible for lower Q and Osc stopping problems? Search this forum for "Q Killer wax" and several threads come up.

I would investigate that before suspecting capacitors which were generally well made parts in those sets as far as I recall.

Re: Trio 9R-59DS
 

This earlier forum thread might be of interest and help:

https://www.vintage-radio.net/forum/...d.php?t=114061

A bit clearer copy of the manual here:

https://www.pa3esy.nl/ontvangers/9R5...0Schematic.pdf

Re: Trio 9R-59DS
 

A few years ago I was given a Trio 9R59DS and the same problem with copying ssb stations. Fortunately I had in the radio room at the time an unused Codar PR30 RF Preselector, with this unit connected to the Trio the problem was instantly resolved with ssb signals with plenty of gain. I suppose that was the easy option and I am still using the rx with the preselector.

Re: Trio 9R-59DS
 

I think the wax going bad is probably overstated. The mica capacitors in these sets are very troubling but often start working when heated. I think that’s why people talk about melting the wax makes a repair it’s actually the heat. These sets are stunning performance by today’s standards. The main thing they had in there favour was the price new

Re: Trio 9R-59DS
 

Chris,

Thanks for ypour videos on the 9R-59DS, very entertaining AND instructive. I've watched them all carefully and tried to copy your approach. Heating the tuning circuitry associated with Band C fixed the problem of zero reception at the low-frequency end of the band. AM recption is fine, but I am still trying to fix the issue of very low audio (volume) with SSB signals. I've ordered a couple of replacement valves associated with the BFO/SSB side. Fingers crossed they make a difference.

I have not changed any caps.

Any thoughts?

Best regards,

Malcolm
G4TJK

Re: Trio 9R-59DS
 

I certainly found electrically leaky electrolytic capacitors in my set and I'm not talking about the smoothers. Cathode bypass IIRC.

Re: Trio 9R-59DS
 

Again a lot of the capacitors in the metal cans are paper and all the ones I changed on my 9R were found to be very leaky although the capacitor value remains good. Good luck

Re: Trio 9R-59DS
 

One post moved to a new thread here:-

https://www.vintage-radio.net/forum/...d.php?t=180635