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Reviews Categories | Transmitters: Commercial/Military/Marine adaptable to ham use | SEA ESP-520 ACSB mobile transveiver Help

Reviews Summary for SEA ESP-520 ACSB mobile transveiver
Reviews: 2 Average rating: 5.0/5 MSRP: $Unknown
Description: Amplitude Compandored SSB mobile transceiver that can be modified for use in the 222 ham band.
Product is not in production.
More info: http://
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KK6BQX Rating: 5/5 Dec 11, 2015 19:28 Send this review to a friend
Great radio, movable to HAM with an effort  Time owned: more than 12 months
These are great radios, I got a few in 2013, they have very narrow band signal.

For 220 MHz, FCC rules narrowband 5 kHz spaced channels provide for a 4 kHz authorized bandwidth.
The emission type is 4K00J3E, i.e., assigned channel frequency 2 kHz.
Audio frequencies transmitted in two spans: the voice audio in the range of 300 to 1600 Hz is emitted from 1650 to 350 Hz below the carrier,
then voice audio frequencies from 1600 to 2900 Hz are emitted from 350 to 1650 Hz above carrier.
The 700 Hz gap is used for the data and trunking control. The signal is very narrow, so receiver depends on the pilot signal, which is +1950 Hz to the carrier.
It gives 200 channels in 1MHz!

I spent some time in 2014 to understanding these radios. The radio can be moved on 222 with the effort, but for the full move it will be required to re-tune helical filters on Rx and Tx
I used a less invasive method to move, but it gives very limited frequency range in the HAM band.

- Built well for very narrow channelling
- Can be used in conventional mode (non-trunking)
- 20W
- Learn a lot

- The radio was designed for trunking system, several things depend on the presence of the repeater.
- Microphone jack is RJ45, it hard to find original SEA mike, (I'm using Kenwood mike through home brew adapter).
- Communication requires ACSB radios on both ends

K6ZRX Rating: 5/5 Jun 13, 2015 20:54 Send this review to a friend
Fun project converting a great radio to ham use  Time owned: more than 12 months
These radios, like the ESP-1000 repeater can be modified for ham use. The mod is complex and involved, but possible with knowledge and the proper test equipment.

Transmitter is 20 watts PEP with a bandwidth of 4kHz. Receivers are very sensitive with a squelch sensitivity of .08uV, much less than a FM receiver. The mobile tracks a data burst from the repeater to indicate when you are out of range of the repeater and to lock the mobile to the repeaters frequency. TX stability when on a repeater is .75PPM and 1.5PPM on simplex. The range is about the same as a 100 watt 2 meter FM rig. The only downside, being an AM system, is pulse type interference(ignition noise). There is no noise blanker, so ignition noise can cut range quite a bit depending on your car's ignition system.

We have been very happy with our ACSB system and the many, many hours of research, experimentation, and modifications was well worth it.

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