[1000mp] Reduced signal level on receive

[Tod Olson]

Great suggestions Dan.

I am sure the attenuator is not on. But I did not do the processor
reset/reboot. 

I do want to use the signal generator to verify that the signal attenuation
is essentially the same on every band, even the WARC bands which I do not
have antennas for.

I did try the antenna input to the antenna A and antenna B ports and found
that the performance was the same.

Thanks for the thoughts.

73, Tod, K0TO

On 1/18/14, 12:02 PM, "Dan Z" <k2ywe at yahoo.com> wrote:

> 
> 
> I hate to ask the obvious, but are you sure the attenuator is not ON?
> If not:
> Have you compared the RX signal through the RX port vs A/B?
> 
> Before you tear into the rig, I'd suggest a processor reset/reboot.
> I believe the attenuator or at least its control is in firmware.
> I had a strange A/B audio problem in one of my MPs that I would have sworn was
> a hardware problem but turned out to be fully cured with a hard reset of the
> processor.
> YMMV
> GL,
> Dan
> 
>  
> Dan Zeitlin - K2YWE
> South Shore ARC - K3AU
> Annapolis, Maryland
> http://danzee.org
> 
> 
> ________________________________
>  From: Tod Olson <tod at k0to.us>
> To: Ft1000MP <1000mp at mailman.qth.net>
> Sent: Saturday, January 18, 2014 1:35 PM
> Subject: [1000mp] Reduced signal level on receive
>  
> 
> I noticed yesterday that there is reduced signal level [not zero signal
> level] on RX with one of my FT1000MP¹s. Since I have two identical radios I
> compared the signals from the same antennas applied one at a time to each of
> the radios. The signal reduction appears to be present on all bands.
> 
> My next test will be to inject a known signal level from a signal generator
> and verify that the signal reduction is essentially constant across all of
> the bands. I expect that test to be positive ‹ essentially constant
> reduction of RX signal across all bands.
> 
> From the service manual I see that on the input to the BandPass filter board
> there is a relay that connects the antenna to the output of the bandpass
> filters when transmitting and connects to the RX input circuits when
> receiving. In the receive path there is an unusual symbol classified as a
> diode but which looks like back-to-back diodes. This item shunts the RX line
> to ground. In the parts list it is identified as a Œsurge¹ item. I suspect
> that when operating SO2R and at one point not having a Dunestar 600 Bandpass
> filter in place, the voltage on the RX line from pickup when the other radio
> was transmitting at 1500 watts on a different antenna may have stressed this
> ³surge diode². 
> 
> I wonder if anyone has had experience with this ³surge diode² failing. Is
> the part still available from Yaesu? Etc.
> 
> Tod, K0TO
> 
> 
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