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by Daniel Wee
Sun 14 Feb 14 2021 8:33 pm
Forum: Radios
Topic: ICOM IC-7300 and IC-9700
Replies: 2
Views: 82

Re: ICOM IC-7300 and IC-9700

The IC-7300 uses an MP7741 audio power amplifier IC in quite an elaborately filtered configuration.
by Daniel Wee
Sun 14 Feb 14 2021 8:23 pm
Forum: Radios
Topic: ICOM IC-7300 and IC-9700
Replies: 2
Views: 82

Re: ICOM IC-7300 and IC-9700

Documents for the IC-9700.
by Daniel Wee
Sun 14 Feb 14 2021 8:22 pm
Forum: Radios
Topic: ICOM IC-7300 and IC-9700
Replies: 2
Views: 82

ICOM IC-7300 and IC-9700

Approved for use in Singapore. The following are the documentation and service manual.
by Daniel Wee
Sun 14 Feb 14 2021 11:55 am
Forum: Radios
Topic: Yaesu radios' audio output stages
Replies: 2
Views: 76

Re: Yaesu radios' audio output stages

Interestingly, ICOM also uses the LA4425A in the output stages, for example in the IC-718 (pg.16 of attached file). This has been confirmed to exhibit that hiss at zero volume as well.

The FT-DX101MPD, on the other hand, uses the TDA2003 power amplifier chip.
by Daniel Wee
Sun 14 Feb 14 2021 10:47 am
Forum: Radios
Topic: Yaesu radios' audio output stages
Replies: 2
Views: 76

Noise in output

The noise in the output of the amplifier does not change with volume, so it must be inherent to one of these three parts - the M62364FP, NJM2737 or the LA4425A. The NJM2737 is specifically a low noise part so I'm not suspecting it as a noise source at the moment. The M62364 has only 8-bits so it is ...
by Daniel Wee
Sun 14 Feb 14 2021 10:38 am
Forum: Radios
Topic: Yaesu radios' audio output stages
Replies: 2
Views: 76

Yaesu radios' audio output stages

Most of Yaesu radios appear to employ the same kind of design:- 1. Various audio signals AFOUT, AFOUT2, TONE comes into a 8-bit digital volume control chip M62364FP chip. 2. The output of this chip is mixed without gain using a single NJM2737 op-amp stage. 3. The output of this mix is fed into the L...
by Daniel Wee
Wed 10 Feb 10 2021 12:09 am
Forum: General Discussions
Topic: Setting up FT-DX10 with JTDX
Replies: 0
Views: 65

Setting up FT-DX10 with JTDX

1. Install drivers for the CP2105 USB-serial chipset (can be obtained from the Yaesu page) https://www.yaesu.com/downloadFile.cfm?FileID=16755&FileCatID=42&FileName=CP210x%5FWindows%5FDrivers.zip&FileContentType=application%2Fx%2Dzip%2Dcompressed 2. In the radio, select FUNC->Radio Setti...
by Daniel Wee
Mon 08 Feb 08 2021 9:49 pm
Forum: General Discussions
Topic: SARTS Repeaters
Replies: 14
Views: 1600

Re: SARTS Repeaters

Even with the voltage increased to 13.8V (actual was 13.7V) and the lowered TX current, we still managed to reach thermal foldback in about 35-minutes of operation. This was shorter than the 45-minute 100% duty-cycle dummy load test, suggesting that maybe SWR is more critical than we had assumed. A ...
by Daniel Wee
Mon 08 Feb 08 2021 8:37 pm
Forum: General Discussions
Topic: SARTS Repeaters
Replies: 14
Views: 1600

Re: SARTS Repeaters

Further testing reveals that the repeater will still overheat at 25W output after about 35-minutes of continuous usage. We do not know if this overheating condition has always been happening (for years). All we know is that we have just noticed it - possibly as a result of higher repeater usage and ...
by Daniel Wee
Mon 08 Feb 08 2021 2:25 pm
Forum: General Discussions
Topic: SARTS Repeaters
Replies: 14
Views: 1600

Re: SARTS Repeaters

Last night's usage test showed the repeater heating up from ambient and took about 25-30 mins to reach the point where the TX LED started to blink and about five more minutes before there was noticeable power output drop. Work done today:- 1. Checking actual voltage at the radio. When receiving, it ...