Kenwood Trio R-600 refurb tips? - UK Vintage Radio Repair and Restoration Discussion Forum

gridrunner · 12th Jan 2022, 2:45 pm

Hi everyone,

I've set myself the goal of picking up my foundation license this year and have recently acquired a simple receiver to embark on a bit of listening. It's a Kenwood R-600 and it's the same model radio used by my grandad back in the 80s, and one I would listen to when I'd visit them at the weekend, so it's lovely to have the R-600 for that reason.

The set is working fine, so I don't want to alter that condition! However, being an inveterate tinkerer - is there anything I should do by way of gentle refurbishment or checks?

Any thoughts on this much appreciated

Stu

Andrew2 · 12th Jan 2022, 3:19 pm

Hi Stu - the R600 was a nice little receiver from the late 70's/early 80's. I had the R1000, it's bigger brother and sold it after a few years and wished I hadn't! I would advise against tinkering or modding if there's nothing obviously wrong. Even if the mods themselves do no harm, the very act of pulling off the covers and disturbing the innards can introduce baffling problems by dislodging connectors or trapping wires etc.
I'd just enjoy it as it is.

Superscope · 12th Jan 2022, 3:49 pm

Apart from the usual checks on the PSU for any signs of Bulging or
distressed Capasitors, I would leave it well alone and enjoy it if it's
working Ok.

The only Modification I know of, is the 12v DC Power Input mod, if
it isn't already fitted. It was an optional accessory at the time.
I don't remember seeing any other tinkering Mods for this receiver.

Edit # Post crossed with Andy #

Ian

gridrunner · 12th Jan 2022, 11:14 pm

Thanks for the tips Ian and Andy. It’s good advice not to disturb things too much. I have had the top and bottom covers off to have a look and apart from heaps of dust, the only thing that needs attention is a bulging 4700uf capacitor and the bottom board where the micro electronics appear to be located.

What’s best for getting started with an antenna?

turretslug · 13th Jan 2022, 12:27 am

Is the bulge in the 4700uF capacitor hard or soft?- if soft, it may simply be the end insulating disc incrementally inflating over the years, the sleeve and the underlying disc acting as a crude one-way valve causing the cap to slowly puff up over time with heat-cool cycling. I've seen folk misled by this, it can look dramatic but the underlying aluminium can end is still perfectly flat. On the other hand, a hard end bulge implies that the can has pressurised somewhat with excess ambient heat and/or ripple current and the capacitor is likely to have dried out and deteriorated.

Beware of rushing in with mods and changes too soon with something that is otherwise working- it's tempting sometimes but get fully used to how something is working for a while, then you'll get a better idea if anything that you do to it subsequently is a genuine improvement!

The advice re. general listening aerials hasn't changed much over decades- long as you can, high as you can (within reason)- but if you're lucky enough to have plenty of land, beware of overloading the front end with a huge aerial. Good luck with it- I always thought that the R-600 looked like a nice straightforward but "proper" HF radio but haven't used one,

Colin

Andrew2 · 13th Jan 2022, 12:19 pm

Good advice from Colin.
However, things have changed regarding noise levels in recent years. A longwire antenna is just as effective as it always was, but sadly this type of aerial is very good at picking up local noise from all the new 'stuff' we have in our homes. LED lighting, computers, anything with a switch-mode PSU, you name it.
Things got so bad around here about 20 years ago that I bit the bullet and treated myself to a Wellbrook 1530 loop aerial. To say I was impressed is a massive understatement! Gone was the S-8 of hash and buzz, to be replaced by an almost silent background with signals coming in clearly.
At the time the Wellbrook was a snip at £120, but it has doubled in price in the intervening years. There are a number of good designs of this type of antenna on the net - a quick google of 'Wellgood loop' should get you there.
In your position I'd try a random 'wire out of the window' and see how much noise you get and take it from there. Good luck, the bands are quiet these days as the utilities have mostly gone satellite and/or digital and conditions are pretty dismal.

David G4EBT · 13th Jan 2022, 4:43 pm

Lots of videos on youtube as to how it should perform, such as these:

https://www.youtube.com/watch?v=6yOfcMDAjkk

https://www.youtube.com/watch?v=i_tuCZERmqc

There's only one mod I've come across (there are none on the 'MODS DK' website), which is:

'How to cure backlash on the epicyclic tuning mechanism and to lubricate it'. (Easy!):

https://www.youtube.com/watch?v=NB-d1WhD6qE

One thing very much in the R600s favour is that it was produce before the onset of SMDs and used through hole components, so at least you have a fighting chance if any repairs do become necessary, though I guess few of us, (leastways not me!), would be too keen to delve into a solid state triple superhet unless it's a glaringly obvious problem.

Nice little set which has great audio - what's not to like?

I'd echo what's been said about Magnetic Loop antennas. Head and shoulders above any other form of antenna. Increased signal strength, and almost compete absence of noise.

If you aren't into homebrew and can afford a Wellbrook, several forum members own one and will testify to it's effectiveness.

If you are into homebrew, the easiest option would to get the 'Wellgood' kit.

I've built two homebrew amplified magnetic loop antennas based on designs by Gary Tempest, which are excellent performers, and can be found at these forum threads:

https://www.vintage-radio.net/forum/...d.php?t=156263

https://www.vintage-radio.net/forum/...t=Loop+Antenna

Every success with your Foundation Licence Stu.

Andrew2 · 13th Jan 2022, 6:04 pm

We seem to be straying off the subject a little, but before we fall off the end I'd like to recommend a company that can supply large, good quality plastic hoops suitable for loop-making.

https://www.etsy.com/uk/listing/7101...sr_gallery-1-1

By gum, that'll need shortening!
I've just got myself a 41 inch dia one. The coloured tape is removable and the hoop itself is very sturdy. Not cheap at about £16 delivered, but worth it IMHO.
The loop will pull apart at the join so you can thread in a single turn of nice thick wire. You'll need to get the length right so you can solder on some thinner tails to allow them to exit the hoop.
BTW, I've found that using more than one turn reduces the loop's performance at the higher frequencies, as does using thin wire. LF response (down to 16 kHz) remains about the same.

12th Jan 2022, 2:45 pm	#1
gridrunner Pentode Join Date: Jun 2008 Location: Manchester, UK. Posts: 227	Kenwood Trio R-600 refurb tips? Hi everyone, I've set myself the goal of picking up my foundation license this year and have recently acquired a simple receiver to embark on a bit of listening. It's a Kenwood R-600 and it's the same model radio used by my grandad back in the 80s, and one I would listen to when I'd visit them at the weekend, so it's lovely to have the R-600 for that reason. The set is working fine, so I don't want to alter that condition! However, being an inveterate tinkerer - is there anything I should do by way of gentle refurbishment or checks? Any thoughts on this much appreciated Stu Attached Thumbnails

12th Jan 2022, 3:19 pm	#2
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Kenwood Trio R-600 refurb tips? Hi Stu - the R600 was a nice little receiver from the late 70's/early 80's. I had the R1000, it's bigger brother and sold it after a few years and wished I hadn't! I would advise against tinkering or modding if there's nothing obviously wrong. Even if the mods themselves do no harm, the very act of pulling off the covers and disturbing the innards can introduce baffling problems by dislodging connectors or trapping wires etc. I'd just enjoy it as it is. __________________ Andy G1HBE.

12th Jan 2022, 3:49 pm	#3
Superscope Octode Join Date: May 2017 Location: St Austell, Cornwall, UK. Posts: 1,018	Re: Kenwood Trio R-600 refurb tips? Apart from the usual checks on the PSU for any signs of Bulging or distressed Capasitors, I would leave it well alone and enjoy it if it's working Ok. The only Modification I know of, is the 12v DC Power Input mod, if it isn't already fitted. It was an optional accessory at the time. I don't remember seeing any other tinkering Mods for this receiver. Edit # Post crossed with Andy # Ian

12th Jan 2022, 11:14 pm	#4
gridrunner Pentode Join Date: Jun 2008 Location: Manchester, UK. Posts: 227	Re: Kenwood Trio R-600 refurb tips? Thanks for the tips Ian and Andy. It’s good advice not to disturb things too much. I have had the top and bottom covers off to have a look and apart from heaps of dust, the only thing that needs attention is a bulging 4700uf capacitor and the bottom board where the micro electronics appear to be located. What’s best for getting started with an antenna?

13th Jan 2022, 12:27 am	#5
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,394	Re: Kenwood Trio R-600 refurb tips? Is the bulge in the 4700uF capacitor hard or soft?- if soft, it may simply be the end insulating disc incrementally inflating over the years, the sleeve and the underlying disc acting as a crude one-way valve causing the cap to slowly puff up over time with heat-cool cycling. I've seen folk misled by this, it can look dramatic but the underlying aluminium can end is still perfectly flat. On the other hand, a hard end bulge implies that the can has pressurised somewhat with excess ambient heat and/or ripple current and the capacitor is likely to have dried out and deteriorated. Beware of rushing in with mods and changes too soon with something that is otherwise working- it's tempting sometimes but get fully used to how something is working for a while, then you'll get a better idea if anything that you do to it subsequently is a genuine improvement! The advice re. general listening aerials hasn't changed much over decades- long as you can, high as you can (within reason)- but if you're lucky enough to have plenty of land, beware of overloading the front end with a huge aerial. Good luck with it- I always thought that the R-600 looked like a nice straightforward but "proper" HF radio but haven't used one, Colin

13th Jan 2022, 12:19 pm	#6
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Kenwood Trio R-600 refurb tips? Good advice from Colin. However, things have changed regarding noise levels in recent years. A longwire antenna is just as effective as it always was, but sadly this type of aerial is very good at picking up local noise from all the new 'stuff' we have in our homes. LED lighting, computers, anything with a switch-mode PSU, you name it. Things got so bad around here about 20 years ago that I bit the bullet and treated myself to a Wellbrook 1530 loop aerial. To say I was impressed is a massive understatement! Gone was the S-8 of hash and buzz, to be replaced by an almost silent background with signals coming in clearly. At the time the Wellbrook was a snip at £120, but it has doubled in price in the intervening years. There are a number of good designs of this type of antenna on the net - a quick google of 'Wellgood loop' should get you there. In your position I'd try a random 'wire out of the window' and see how much noise you get and take it from there. Good luck, the bands are quiet these days as the utilities have mostly gone satellite and/or digital and conditions are pretty dismal. __________________ Andy G1HBE.

13th Jan 2022, 4:43 pm	#7
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: Kenwood Trio R-600 refurb tips? Lots of videos on youtube as to how it should perform, such as these: https://www.youtube.com/watch?v=6yOfcMDAjkk https://www.youtube.com/watch?v=i_tuCZERmqc There's only one mod I've come across (there are none on the 'MODS DK' website), which is: 'How to cure backlash on the epicyclic tuning mechanism and to lubricate it'. (Easy!): https://www.youtube.com/watch?v=NB-d1WhD6qE One thing very much in the R600s favour is that it was produce before the onset of SMDs and used through hole components, so at least you have a fighting chance if any repairs do become necessary, though I guess few of us, (leastways not me!), would be too keen to delve into a solid state triple superhet unless it's a glaringly obvious problem. Nice little set which has great audio - what's not to like? I'd echo what's been said about Magnetic Loop antennas. Head and shoulders above any other form of antenna. Increased signal strength, and almost compete absence of noise. If you aren't into homebrew and can afford a Wellbrook, several forum members own one and will testify to it's effectiveness. If you are into homebrew, the easiest option would to get the 'Wellgood' kit. I've built two homebrew amplified magnetic loop antennas based on designs by Gary Tempest, which are excellent performers, and can be found at these forum threads: https://www.vintage-radio.net/forum/...d.php?t=156263 https://www.vintage-radio.net/forum/...t=Loop+Antenna Every success with your Foundation Licence Stu. __________________ David. BVWS Member. G-QRP Club member 1339.

13th Jan 2022, 6:04 pm	#8
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Kenwood Trio R-600 refurb tips? We seem to be straying off the subject a little, but before we fall off the end I'd like to recommend a company that can supply large, good quality plastic hoops suitable for loop-making. https://www.etsy.com/uk/listing/7101...sr_gallery-1-1 By gum, that'll need shortening! I've just got myself a 41 inch dia one. The coloured tape is removable and the hoop itself is very sturdy. Not cheap at about £16 delivered, but worth it IMHO. The loop will pull apart at the join so you can thread in a single turn of nice thick wire. You'll need to get the length right so you can solder on some thinner tails to allow them to exit the hoop. BTW, I've found that using more than one turn reduces the loop's performance at the higher frequencies, as does using thin wire. LF response (down to 16 kHz) remains about the same. __________________ Andy G1HBE.