Alinco DR-235 Mk II Receive Problems

[hamstang]

Myself and 3 other hams have a total of 5 of these 220mhz radios in service. 3 of the newest radios have developed intermittent very noisy receive issues regardless of signal strength, and on multiple repeaters. The radios are out of warranty. Anyone else experiencing simular issues, or know of a fix?

 

[ShawnInPaso]

I have the same rig, installed in my car and it has experienced the same problem.

When I purchased the radio from a guy on eBay, it was a bargain price but advertised as 'like new'. In fact, it was "like new" and after installation in my car, with a new 220 antenna all was good. But within days, the RX starting making some noises which sound more like a loose antenna connection, or a bad antenna connection. Since it was just installed I wasted some time troubleshooting antenna problems when in fact it was the radio.

Anyway, after some troubleshooting of the radio, it simply turned out to be dust or "stuff" that worked it's way into the chassis. Apparently the SMT design and dirt, dust, or particles that get into the thing created just enough havoc that the RX sort of "crackles" (for lack of a better description).

All I did was remove the top and bottom of the chassis and blow out / clean the internals. This was about a year ago or more and the problem has not returned.

 

[hamstang]

Thanks Shawn. Crackles is a great description of the audio I think. We have been thinking the problem was possibly related to the circuit boards as you described.

73

Vern WJ4S

 

[ramal121]

Sounds like a noisy VCO. If you have someone transmit nearby (no voice, just a full quieting carrier), you can turn the mobiles volume all the way up and then tap around the inside with the butt of a screwdriver and listen for pops or microphonics. And yes grunge is the culprit. Sometimes you can cure it by tightening the board and/or shield screws. If it's really bad, you'll have to disassemble the board and clean up the grounding lands and shields. Everything needs to be clean and tight.

 

[gewecke]

I've waited to buy a 220mhz. mobile to go with my ht's just for this reason. Now I'm torn between the dr-235 and that wouxun 220mhz. rig?? The wouxun model claims 55 watts and 220-260mhz.
I wonder if that's not the same radio in a different case....

73,
n9zas

 

[emrtech]

Possible Solution to a Noisy Alinco DR235 Receiver Problem

In the hope this report might help I may have a solution to resolve the noisy DR235 receiver problem. I purchased recently a DR235 from eBay which was advertized as "Like new".

Anyways, I received it today and noticed a very audible hiss even with a strong signal from a professional mobile Radio Tester. It was apparent that the PLL was modulated with a hiss.

Personally, I feel, the designers should have added an active noise reduction filter before feeding the 8V to the PLL. It is bad design practice to supply the sensitive VCO circuit with unfiltered DC.

Performing some basic troubleshooting checks quickly revealed a noisy 7808 Three-terminal voltage regulator. I replaced the 7808 with a Motorola made regulator and the problem immediately disappeared, producing beautiful clean audio and a perfectly quiet background. Judging from information found on the Internet, I believe I am not the only one having had this problem and would like to suggest changing the regulator if you may have the same trouble.

Otherwise, this seems like a very nice little radio. The TX audio is crisp and clear and the receiver is also quite sensitive. So, I think I should be happy now with the radio;-)

Good luck with your repairs should you need to fix a similar problem. It is worth checking out.

Greetings from Canada,
Gerhard

 

[ShawnInPaso]

Your post was very helpful emrtech. Too bad you've only posted once; perhaps this follow-up info will help the next guy with a noisy DR235.

After my earlier post above, I began using my DR235 more frequently. That old familair noise started occurring again, so I checked the radio and cleaned it as per my note above. Sadly the noise did not go away, which led me back here and I read your advice.

Also - I phoned the authorized Alinco repair service (very friendly and helpful ham operator spoke with me). He suggested it was one of the filters causing the problem (there's a wide and narrow filter).

So, I had a choice to make, replace the regulator, the filter or both? If I replaced both, I'd never really know the source of the problem. I noticed that the regulator is easier to replace, so that's what I did first.

It's been a month now, no noise whatsoever from the receiver. I'm hoping it stays that way and I suspect you had it right with the advice provided.

Thanks emrtech!