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Old 21st Nov 2009, 10:41 pm   #1
HEAVY747
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Default Swinburne DR600 Airband Radio will not tune

Hi All

Please please help:

I purchased a Swinburne DR600 airband monitor (which I have been after since 1982) off a old gentleman who had obviously tampered with it. The LCD display does not increment with the movement of thumb wheel but I get hiss output from speakers and some airband transmissions.

See links:

http://www.youtube.com/user/bizzwhiz.../0/vV6pEDrZbuM

http://www.youtube.com/user/bizzwhiz.../1/_cLYndN5W-c

Circuit diagrams of circuit and LCD display used (PCIM177):

http://gb.espacenet.com/search97cgi/...n/textdraw.hts

http://www.milair.co.uk/FC177.pdf

The radio has been left on for 24hrs to drain rechargeable battery but is still hissing away.

I can supply more information if required.



What could be wrong please help!!!!!!

Many Thanks
HEAVY747
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Old 23rd Nov 2009, 10:35 pm   #2
Biggles
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Default Re: Swinburne DR600 Airband Radio will not tune

Hi, can you give a bit more info like what's the display showing and maybe a photo or some more symptoms. I've never heard of this radio but have a bit of experience on airband sets and have used the display module you mention so may be able to help. Sounds as if you may just have some kind of mechanical problem with the thumbwheel tuning. Can't get the circuit links you have provided to work.

Biggles
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Old 24th Nov 2009, 12:33 am   #3
Oldtimer74
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Default Re: Swinburne DR600 Airband Radio will not tune

I know very little that will help but I could get the first link to work which shows someone operating the set but the display does not change. I guess therefore that the frequency is not changing and the hiss is due to there being no signal on that channel. Sorry transistors are an anathema to me!
Pat G3IKR
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Old 24th Nov 2009, 9:22 pm   #4
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Default Re: Swinburne DR600 Airband Radio will not tune

Hi, I don't know this receiver but...
Am I correct in assuming it's a 6 channel receiver, the thumbwheel is for fine tuning?
The screen reads 389.31 (MHz?) is this any where near the frequency you want to receive.
How many crystals are fitted?
Do you have access to a signal generator / frquency counter?
You say you received some signals, did the tuning appear to work? It may be just the frequency display module is faulty.
You say it appears fiddled with, in what way?
If you want to pop it in the post, I'll gladly try and make some sense of it.
Can't really help any more without a bit more detail.
Rob.
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Old 25th Nov 2009, 11:51 am   #5
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Default Re: Swinburne DR600 Airband Radio will not tune

This receiver should be tunable between 118 and 136 Megs. It may well be tuning properly, but the display module may not be working correctly. As with marine band, you need to be reasonably close to the source to receive intelligible transmissions.
Neil
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Old 25th Nov 2009, 7:25 pm   #6
Biggles
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Default Re: Swinburne DR600 Airband Radio will not tune

It could be tuned to military airband rather than civil, with a frequency like that on the display, but if the display is reading accurately, I suspect that part of the band may now be allocated to Tetra transmissions i.e. Airwave. I suppose it may be worth getting a signal genny connected to it and tuning around for that, then at least you would know it was just the display faulty. If it's got crystals then this may well be an expensive problem.

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Old 27th Nov 2009, 5:47 pm   #7
HEAVY747
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Default Re: Swinburne DR600 Airband Radio will not tune

Hi All

My sincerest aplogies for late reply.

The problem turned out to be the local oscillator which needed retuning with correct applied to receiver. Also the radio had board fll of dry joints which were all re-soldered and re-touched Now I have a beautifully working airband monitor a which functions fully.

I did get email help from Ron Swinburne as to what could be wrong - been after one of the radios since 1982!!

Absolutely love using it.

Cheers
HEAVY747
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Old 27th Nov 2009, 7:58 pm   #8
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Default Re: Swinburne DR600 Airband Radio will not tune

I have had one in the loft for a while after I blew the charging regulator up. It is now working and is at work. This is ideal as the Gatwick is next door.
Would love a circuit as the unit drifts on warm up when the presets are selected.
Any idea what crystals are used?
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Old 27th Nov 2009, 8:05 pm   #9
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Default Re: Swinburne DR600 Airband Radio will not tune

I have removed all crystals as the set plays up.

Last edited by Darren-UK; 30th Nov 2009 at 1:27 am. Reason: OT stuff removed.
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Old 29th Nov 2009, 6:14 pm   #10
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Default Re: Swinburne DR600 Airband Radio will not tune

Great little radio - I have one in the loft, and remember visiting Ron at Birmingham, as I had worked at Ambit International, where most of the parts were sourced from !! I seem to remember you can actually dispense with the xtals and on mine there are two positions wired to a 10t preset pot which allows you to select frequencies to suit. Can dig it out if you are interested in this mod ?

Regards

John
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Old 1st Dec 2009, 7:42 pm   #11
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Default Re: Swinburne DR600 Airband Radio will not tune

Milairuk, that would be very interesting, I don't suppose you have a circuit for it as well?
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Old 1st Dec 2009, 9:07 pm   #12
milairuk
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Default Re: Swinburne DR600 Airband Radio will not tune

I'll dig it out at the weekend, need to put the display back in as I was using it as a frequency counter ! I'm pretty sure it was based around Toko IC's aka Ambit days, if so shouldn't be too difficult to work out (I hope) Mine has also got some xtals, I'll work out the required frequencies if poss. Pretty busy at present, so please bear with me.

73

John
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Old 2nd Dec 2009, 2:50 pm   #13
HEAVY747
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Default Re: Swinburne DR600 Airband Radio will not tune

Milairuk please count me in too - any circuit diagrams gratefully accepted
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Old 4th Dec 2009, 3:28 pm   #14
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Default Re: Swinburne DR600 Airband Radio will not tune

Thanks John.
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Old 6th Dec 2009, 6:46 pm   #15
milairuk
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Default Re: Swinburne DR600 Airband Radio will not tune

Started trying to draw out the circuit diagram, it' s not the easiest of things to do, Heavy 747 you mentioned emails to Ron, does he not have a circuit still available ? I'll persevere, the RF and MIxer are fine, but the Osc seems to be rather strange as is the Xtal circuitry. At present I cannot see any local osc feed to the Mixer other than by close coupling ?
The 2nd IF/AF in mine is a TDA1083, but I notice that your one on youtube has a Hitachi HA1223 ? fitted. Trying to work out the switching along with the digital scan is also proving a challenge. Must try to contact Dr Who and get him to take me back 20 years when my eyesight was much better for this sort of thing !
Pleased to say that after putting back the LCD display it still works fine.

73
John
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Old 6th Dec 2009, 10:00 pm   #16
HEAVY747
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Default Re: Swinburne DR600 Airband Radio will not tune

Sorry Ron never got back to me with the notes or circuit diagram - I guess he must be busy like us too.
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Old 7th Dec 2009, 1:46 pm   #17
milairuk
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Default Re: Swinburne DR600 Airband Radio will not tune

Quote:
Originally Posted by HEAVY747 View Post
Sorry Ron never got back to me with the notes or circuit diagram - I guess he must be busy like us too.
Ok, I'll persevere, I would have thought he had long retired by now

John
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Old 8th Dec 2009, 7:54 pm   #18
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Default Re: Swinburne DR600 Airband Radio will not tune

The set I own seems good apart from it's tendency to drift a few KHz on warm up. I am running mine off a 12V DC supply but it might work better with a higher voltage. The set is easily overloaded by adjacent signals from Gatwick airport next door. Squelch seems to be like a field gate, Wide open or shut!
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Old 9th Dec 2009, 2:06 pm   #19
milairuk
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Default Re: Swinburne DR600 Airband Radio will not tune

Quote:
Originally Posted by Superhet Si View Post
The set I own seems good apart from it's tendency to drift a few KHz on warm up. I am running mine off a 12V DC supply but it might work better with a higher voltage. The set is easily overloaded by adjacent signals from Gatwick airport next door. Squelch seems to be like a field gate, Wide open or shut!
12v should be fine as it has an internal regulator running at around 5v. Selectivity is only provided by a couple of ceramic filters in series, I seem to remember they had a B/W of about 12.5Khz, but they might be wider. It's probably 35 years since I reviewed it for Radio & Electronics World mag. Mine has got serial number 0060, so it's one of the first they made. Still working on the circuit, have a cunning plan to photo the PCB, enlarge and print it so I can see the tracks a bit better !!

John
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Old 11th Dec 2009, 4:23 pm   #20
HEAVY747
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Default Re: Swinburne DR600 Airband Radio will not tune

Wow Milairuk!!! You must have loved your job - I know I would have!! How many of the radios were made by Swinburne? At present I have a FDK ATC-720 Airbander (See my oter post) which is humming with distorted signal - any ideas. I ma using a smooth dc input voltage with no AC leakage.
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