A pair of Icom bricks - UK Vintage Radio Repair and Restoration Discussion Forum

Steve G4WCS · 23rd Nov 2019, 10:13 pm

Picked up an Icom 260E a while ago. Superb radios.
I keep browsing the internet for possible bargains and managed to get a 260A for £25 with a tuning fault. Its had a couple of nights spent cleaning it up, and its now putting the E to shame, off with its knobs into the dishwasher I think.
The beauty with having a couple is its easier to compare voltages as its probably a dry joint or an expired cap on the control logic board.

onewatt · 24th Nov 2019, 10:04 am

Hi Steve,
I have a 260, think it’s also an “A” with a tuning issue. I struggled to find info on the circuit at the time so I put it on the back burner. I’ll be interested to see what you find.
ATB
Chris
G1rpo

russell_w_b · 24th Nov 2019, 10:54 pm

I have a 260E too: great set. I replaced the meter lamp with a green LED when it failed, which was a bit of a fiddle, and the only trouble I've ever had was a dodgy connection on one of the board plugs which (as I recall) prevented me running CW on 1W. But that was a long time ago and it's been fine since.

Jon_G4MDC · 25th Nov 2019, 9:40 am

It's a pity that Icom have put up the manual minus the circuit diagram...
If you are still looking it can be found at mods.dk

It looks like the PLL runs on a 5.12 MHz crystal divided by 512 so PLL step frequency is 10kHz.
The mix down crystal is driven by a D to A to interpolate the 10k into 100Hz steps.

Are the tuning issues with the 10kHz steps or within each step?

Steve G4WCS · 25th Nov 2019, 11:38 pm

Ill keep you posted on my findings.

23rd Nov 2019, 10:13 pm	#1
Steve G4WCS Heptode Join Date: Sep 2004 Location: Preston, Lancashire, UK. Posts: 632	A pair of Icom bricks Picked up an Icom 260E a while ago. Superb radios. I keep browsing the internet for possible bargains and managed to get a 260A for £25 with a tuning fault. Its had a couple of nights spent cleaning it up, and its now putting the E to shame, off with its knobs into the dishwasher I think. The beauty with having a couple is its easier to compare voltages as its probably a dry joint or an expired cap on the control logic board. Attached Thumbnails

24th Nov 2019, 10:04 am	#2
onewatt Hexode Join Date: Jun 2005 Location: Buntingford, Hertfordshire, UK. Posts: 362	Re: A pair of Icom bricks Hi Steve, I have a 260, think it’s also an “A” with a tuning issue. I struggled to find info on the circuit at the time so I put it on the back burner. I’ll be interested to see what you find. ATB Chris G1rpo __________________ BVWS, VMARS, RSGB, DEHS, RAOTA Nothings too big or too heavy, otherwise it wouldn't be where it is!

24th Nov 2019, 10:54 pm	#3
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	Re: A pair of Icom bricks I have a 260E too: great set. I replaced the meter lamp with a green LED when it failed, which was a bit of a fiddle, and the only trouble I've ever had was a dodgy connection on one of the board plugs which (as I recall) prevented me running CW on 1W. But that was a long time ago and it's been fine since. __________________ Regds, Russell W. B. G4YLI.

25th Nov 2019, 9:40 am	#4
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: A pair of Icom bricks It's a pity that Icom have put up the manual minus the circuit diagram... If you are still looking it can be found at mods.dk It looks like the PLL runs on a 5.12 MHz crystal divided by 512 so PLL step frequency is 10kHz. The mix down crystal is driven by a D to A to interpolate the 10k into 100Hz steps. Are the tuning issues with the 10kHz steps or within each step? Last edited by Jon_G4MDC; 25th Nov 2019 at 9:48 am.

25th Nov 2019, 11:38 pm	#5
Steve G4WCS Heptode Join Date: Sep 2004 Location: Preston, Lancashire, UK. Posts: 632	Re: A pair of Icom bricks Ill keep you posted on my findings.