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Author Topic: Yaesu FT-2900 RX issues  (Read 9740 times)
K4JJL
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« on: December 06, 2011, 09:15:01 PM »

Hey folks,

A friend dropped off her FT-2900 at my house because she said she couldn't hear any repeaters.  After connecting it to my service monitor and checking the usual stuff, here's what I found.

1. TX is operating perfectly (deviation, power out, on freq, etc).
2. RX is operating perfectly when radio is set to NAR (narrowband) in the menu.
3. RX is horrible when running wideband in the menu.

Here's how I define horrible...

A -40 dbm input signal won't open the squelch when set slightly above the noise level w/ no input signal.

When I open the squelch w/ the knob and blasted a -20 dbm signal in the RX, I can hear some raspy audio coming through.  Hardly 12 db SINAD, though.

Any ideas what might cause this?  Cold solder joint on the bandpass filter after the switch?  Bad switch?  I haven't opened the radio yet, but might in the next day or so to see if something has gone microphonic or loose.

Normally, I'd tell her to run the radio in NAR mode, but she's got a quiet voice and needs all the deviation possible.

Thanks,

Jared
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W1EL
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« Reply #1 on: December 07, 2011, 02:02:25 AM »

Interesting! My FT2900 just lost its' RX sense. I haven't dug into it , but the thing took over 10 uV to open the squelch. Everything here is WFM, so I haven't checked narrow.
I was just going to send it to Yaesu, but they want $70/hr to look at it. That, with shipping to CA, seems a lot for a $160 radio.
I'll get it on the bench maybe this weekend. We'll see...

73, Eric
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K4JJL
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« Reply #2 on: December 07, 2011, 10:33:20 AM »

Keep me posted.  I've got family coming in to visit this weekend, so nerdy nonsense for at least a few days.  But if you find something, please let me know.

Thanks!

Jared
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KA5IPF
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« Reply #3 on: December 07, 2011, 12:28:32 PM »

Disclaimer: I can barely spell Yaesu so know nothing about this particular radio.

BUT, Since Yaesu used the Toko 455 filters in their HF rigs (and had some go bad) they may have used them in the 2m rigs. I would pop the cover and look for 2 Toko 455 IF filters, one is for the narrow and one for the wide.

The symptoms you describe exactly apply to a Kenwood D710 with bad filters.

Clif
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K4JJL
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« Reply #4 on: December 08, 2011, 07:08:52 AM »

Clif,

If it has them, how can I test?  Remove and jump out?

If they are bad, do you have any in stock I can buy (or bum) off you?

Thanks,

Jared
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KA5IPF
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« Reply #5 on: December 08, 2011, 09:12:06 AM »

Without knowing exactly what Yaesu uses I would contact them for replacements. I know the Kenwood versions are abt $4 each.

Stir up Yaesu, Kenwood is replacing them for free if the radio falls in a serial number range.

Clif
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W1EL
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« Reply #6 on: December 08, 2011, 04:03:40 PM »

Had my 2900 on the bench for a while today. The RX sense was acceptable when first powered up. After some time, the sense got worse, and then wandered around for a few hours, never really settling down. I've not seen a problem like this before, so I'm a little stumped. Maybe something to do with the varactor tuned front end filter?

Regards, Eric
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KA5IPF
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« Reply #7 on: December 09, 2011, 10:55:35 AM »

Same answer as above.

Clif
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W1EL
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« Reply #8 on: December 10, 2011, 12:35:27 PM »

Thanks, Clif!
Same problem as above! I put it in "narrow" today and it works fine. Now to find a LTM450FW filter. Looks like Yaesu will be the best source. None at Mouser,Newark or Digi-key.

Best regards from Maine, Eric


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W1EL
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« Reply #9 on: December 12, 2011, 09:02:35 AM »

Yaesu part # H3900572 $0.93 ea
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K4JJL
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« Reply #10 on: December 14, 2011, 12:15:56 PM »

Ordered the parts last night.  Figured I'd get both sets (wide and narrow) since the price was so cheap.  Removal of the old ones was a little tedious, but not too bad since they're DIP instead of SMD.
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KA5IPF
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« Reply #11 on: December 16, 2011, 06:50:15 AM »

How did it turn out?

Clif
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W1EL
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« Reply #12 on: December 17, 2011, 08:58:47 AM »

Replaced the wide 450 kHz filter this morning and all is well now.

I did use a couple of choice words while removing the lead-free solder.

Now, I've noticed my 2003 TS2000 is crackling when not on the antenna. sigh.

Thanks, Clif, for your insight.

73 de W1EL 
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K4JJL
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« Reply #13 on: December 22, 2011, 01:11:58 PM »

Mine are still on backorder.

I agree; lead-free solder sucks (or doesn't suck). Grin
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KA5IPF
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« Reply #14 on: December 23, 2011, 09:24:50 AM »

Replaced the wide 450 kHz filter this morning and all is well now.

I did use a couple of choice words while removing the lead-free solder.

Now, I've noticed my 2003 TS2000 is crackling when not on the antenna. sigh.

Thanks, Clif, for your insight.

73 de W1EL 

2003 mfg is before the filter problem. It's most likely something else. Cycle the preamp off and on and see if it goes away when off. Also check Q1 on the tx/rx-1 board. When it breaks down it causes the same symptoms.

Clif
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