The IC-E90 is a tri-band FM handie designed to operate in the 6m, 2m and 70cm amateur bands. For some while there has been interest in a modification which would allow these sets to work in the 4m band too.
A modification published on-line a couple of years ago merely described how to remove the out-of-band inhibit function, so allowing the set to transmit and receive at 70MHz. This took no account of spurious outputs from the transmitter, and one correspondent had interference problems reported by local military air traffic control!
Happily, one of the major UK dealers can now supply these sets ready-modified for 4m use with the inclusion of a filter to reduce spurious outputs, although they can only achieve a second-harmonic suppression of around 33dB, so it is not advisable to use the rig into a external antenna or amplifer without additional external filtering.
Steve G1KXP recently acquired one of these sets, and got together with Ian G6TGO and Dave M3CRV to give it a try on 4m. Here is their test report:
These tests were conducted from the QTH of G6TGO near Sale in Cheshire, mostly using a Sirio vertical antenna at 15ft asl. The E90 has an SMA antenna socket, so a patch-lead was used to convert this to an in-line BNC socket (inter-series adapters are available, but there is always a concern that when attached to a heavy cable, they put too much stress on the small socket on the top of the set).
The receive performance on 4m was very good: off-air signals were a little stronger than on an Ascom SE550, and no breakthrough was heard from local Fire Brigade services in the adjacent band. (Over the course of extended tests in the following weeks, some breakthrough has been heard at the top end of the band from a nearby Fire Service transmitter on 70.525MHz, which worsened as the battery voltage dropped below 7V.)
Some chopping of signals on 70.475 was heard, but this was attributed to an amateur packet link on 70.4875 from a station only half a mile away.
The squelch is adjusted by pressing a function button below the PTT and turning the knob on top of the unit. The settings available are: OPEN, AUTO,or pre-sets 1-9.
Initial tests at Steve's QTH had indicated slight distortion on the transmitted audio, due to over-deviation. It was then found that the set has an internal menu to select narrow ("off") or wider ("on") deviation. After this adjustment, the audio reports were very favourable, with listeners commenting that they would not have known it was a handheld with an internal microphone.
The maximum RF output power available when using the supplied battery was 2.75 watts (measured on a AV600 bridge), dropping to 2.5 watts on "low" power (on the other bands, there is a much greater differential between the "high" and "low" settings). This was sufficient to have clear contacts with several stations over 20km distant.
The actual contacs made on 4m, using 2.75W into the Sirio were as follows:
Dave M3CRV in Northwich (23km): S5 with QSB.
Roger M0DWQ in Warrington (20km): RS 58.
Phil G8HDS in Rochdale (24km): RS 57, (and 41 with QSB on the set-top helical)
Paul G7ODJ in Warrington (20km): RS 58
Ross G6GVI in Bolton (20km): RS 54
During a brief test on 2m, some breakthrough from strong local paging transmitters was heard when using a dual-band Watson-50 colinear, but this was not as severe as on a handheld scanner coupled to the same antenna.
The portable antennas supplied consisted of a single-band helical for 4m, and a second three-part helical (with the longer top-section it is suitable for 6m/2m/70cm, and with the more compact shorter top it functions as a dual-bander for 2m/70cm).
The 4m helical looks a little out of proportion to the E90 but appears to function well: several contacts have been made over 40km (and one over 70km) using it.
The 4m helical is supplied with a small rubber washer which should be fitted to fill the gap between helical and the SMA connector on the top of the set (be careful to look in the packaging for this small washer when first unpacking your set).
As with all compact set-top aerials (which are small compared with the wavelength), the efficiency is poor, but can be improved by adding a counterpoise to the set. Holding the handie on top of a metal structure such as a car-roof or handrail can help, or why not try fixing a quarter-wavelength (around 40 inches) of wire to the rear belt-clip screw? You may find that as well as improving the effective radiated power, the improved antenna matching will reduce the current drawn, and extend the battery life too.
The set's receive coverage is from HF through to 999.999MHz with wide-FM, narrowband FM and AM modes. Although the set will not receive SSB or CW, when switched to AM, and with a local signal generator used as a BFO, it was able to detect the GB3BUX FSK beacons from Buxton (30km) on both 70.0 and 50.0MHz.
The radio provides 500 memory channels, plus up to five calling channels and 50 scan-limit memories. The UHF TV Band audio frequencies (channels 21-69) are also pre-programmed into memories.
As well as operating as a self-contained handie with integral batteries, the set may also be operated from an external DC supply between 5.5 and 11V (the manual warns that damage will result if this limit is exceeded). A DC-DC converter will therefore be needed if you want to operate from a 12V battery supply. The transmitter will draw up to 2A at full output, and 800mA at 0.5W output.
The transceiver incorporates a battery voltage indicator: with the supplied Li-ion BP217 (7.4V, 1300mAhr), this showed 8.6V when fully charged, and 6.3V when discharged, just before the set shut down. The supplied plug-in charger will re-charge this battery in 16 hours, but cannot supply enough current to power the transmitter. A fast drop-in charger is available as an accessory: this will re-charge the battery in 2.5 hours.
The receiver draws up to 220mA at full audio and 100mA when squelched, dropping to 65mA with the battery saver enabled.
Another accessory is available: a battery case which includes a DC converter to generate 5.5V from just two AA cells. This is sufficient to allow the set to operate on receive for a few hours, and is useful if you do not want to expire your main battery whilst monitoring. It will also manage brief transmissions at a hundred milliwatts output.
The IC-E90 is the only dedicated amateur portable FM transceiver currently available with 4m capability (on UK import models).
The combination of four bands in a small lightweight unit will make it a popular choice with those who like to get out and about with their radio, particularly SOTA enthusiasts.
Its performance is limited by the set-top helical aerial, but if connected to a more effective external antenna, its receiver performance is at least as good as most of the (ex-PMR) sets in widespread use on the band. On transmit, the 2 to 5W output is sufficient for making contacts over tens of kilometres (or over a thousand, if you're lucky with the sporadic-E!).
Note that this review has concentrated on the set's performance on the 4m band only - the rest of its capabilities have not been fully assessed.
Steve purchased his set from Martin Lynch & Sons, and it was supplied with the helical antennas shown above. Having seen and heard it in action, Ian and Dave were straight on the 'phone to order theirs!
The tests were performed by Ian G6TGO, Steve G1KXP and Dave M3CRV, and the review was compiled with additional input from Ross G6GVI.
Thanks also to the other stations who helped with on-air reports, and also to Chris and the team at Martin Lynch & Sons for their technical assistance.