Custom Products from Masters Communications
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Custom Products from Masters Communications |
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Model FL-10 Click Here for schematic, installation, and set-up instructions.
Ordering instructions on bottom of page.
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It is available in two cut-off frequencies - 4 kHz and 15 kHz. This filter is used to low-pass filter ultrasonic content from a USB radio adapter like the RA and DRA Series that allow its installation.
This filter was once available in high-pass configuration, but has been replaced
with the PLF-15 CTCSS Reject Filter.
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Price $10.00 each - in kit form.
Also available assembled and tested - $20.00 each.
USPS Priority (US) and USPS First-Class shipping available to most locations worldwide,
calculated at checkout.
PayPal accepted - order below.
Actual Size FL-10 Top board photo.
(Click image to enlarge)
Description:
It's used as a splatter/ultrasonic content filter for use with the RA-30/33/35/40/42/DR1X,
and DRA-45/50/65/70/80.
Note: These filters are NOT required when feeding audio to any Amateur Radio through the MIC or DATA ports. They are only necessary when you have severely modified a radio eliminating the safety-net audio filtering.
It can be used stand-alone in other applications because of its small physical size.
There are two options for frequency cut-off (knee). One places the knee at approximately 4 kHz, and the other at 15 kHz. Which one you choose depends on your needs. The FL-10 will run from 5 VDC, but that severely limits the P-P output capability. The RA/DRA should be configured for an external voltage source and the supply voltage be at least 10 VDC. Maximum supply voltage is 16 VDC, as that's the maximum voltage the LM386's will handle.
When used stand-alone, or with the RA-30 and RA-33, the filter can be powered with up to 30 VDC.
Current draw at 12VDC is under 1mA for the LPF increasing slightly when passing audio.
The frequency response was tested with an input level of 2.44Vrms, or +10dBm, which was well below the maximum, using a 12V power supply. The output level was exactly the same as the input level (i.e. unity gain) at 5 kHz, the middle of each pass-band. The distortion at this level was around 0.03%. The signal was considered unacceptable when it reached 1% distortion. With a 5V power supply, this occurred at about 0.6Vrms or 1.7Vp-p and the maximum output level was 0.9Vrms or 2.7Vp-p, but that had almost 5% distortion. Clipping occurred first on the negative peaks of the output waveform. With a 12V power supply, 1% distortion occurred at about 3.3Vrms or 9.6Vp-p and this was also the maximum output level. Clipping was symmetrical with higher input levels.
These filters have undergone several stages of optimization, performed by Robert Meister
WA1MIK. Bob used his audio talents to choose the component values and prove the performance of
each filter.
Be sure to read Bob's evaluation
article.
Click Here for schematic, installation, and set-up instructions.
Secure PayPal ordering is available by emailing Kevin at the link below.
Email
Kevin Custer for ordering information.
Product of Masters Communications, all rights reserved.
Specifications may change without notice.
Images are property of Kevin Custer - Masters Communications
Filter optimization performed by Robert Meister - WA1MIK.
Board layout by Kevin Custer - W3KKC.
HTML February 17, 2016 W3KKC All Rights Reserved!