One problem the RA17 suffers from is that of not having a product detector.The BFO has a very useful "swing" either side of the required frequency but does not give "true" single sideband reception.
Enter the RA63 SSB Adaptor.
The RA63 is connected to the RX by means of the 100kcs if output socket on the rear chassis and apart from connecting it to a mains power supply that is all you have to do to resolve true SINGLE sideband.The control to the left of the unit enables you to fine tune the received signal by up to +-1khz..Next comes the power switch,then the USB/LSB selector,Marked for both the RA17 and RA117.We then have the AF Gain control,next the speaker on off switch,a speaker,and finally a headphone socket.
On the rear of the chassis are input and output jacks for IF and audio plus the usual power items.
This unit is best suited to SSB use as the filters are optimized for this mode.
Next we come to the RA98 ISB adaptor.Note that ISB stands for INDEPENDENT SIDEBAND unlike Single SideBand in the RA63.
The idea of ISB is that you can demodulate either sideband independently of the other.The RA98 works in a similar way to the RA63 but unlike the RA63 where you only take one sideband the RA98 enables you to take either or both sidebands.The RA98 also has a mechanical Automatic Frequency Control (AFC) system.
Originally the RA98 was intended for multi channel work enabling more than one link to be used on a channel (probably four?).The transmitter would transmit a pilot tone and the AFC system would lock onto this and eliminate any drift on the circuit (either at the RX or TX end).A connection could be made to the AVC line on the RX to control RX gain as the signal faded.
Well what use is the RA98 to us? It can be used for SSB work, although the filters are a bit wide for this mode.But the main interest for many is that you can lock it onto a broadcast signal where it will track the signal, and by using the two sideband controls you can select either both sidebands for improved quality or, if there is interference to one sideband, you select the other giving selective sideband reception.
The RA298
Under construction.
The RA298 is an ISB adaptor that is designed for use with Receivers such as the RA217,RA1217 , RA1218 etc.and allows reception of Indipendant Sideband and Single Sideband transmissions with suppressed to full carrier signals. It has seperate USB and LSB audio outputs on the rear panel which are avaliable as either balanced or unbalanced outputs and there is provision for headphone monitoring on the front panel. The power supply for the unit is supplied from the receiver it is used with and this is -16 V at 100ma.
AFC is provided within the unit and this feeds a variable 1.7 Mhz frequency to the I.F stage of the associated receiver. If the transmission being received is supressed carrier then an internal 1.7 Mhz crstal oscillator replaces the AFC circuit.An AGC line is avaliable to control the receivers gain so that the input to the RA298 is kept within limits.
Indicator lamps are provided on the front panel . A green "Lock" lamp indicates when the AFC circuit is locked and a red "Carrier Fail" lamp indicates if the carrier is lost.
Variants of the above units.
| RA63A | SSB Adaptor 100 Khz input |
| RA63B | North American version |
| RA63C | With 465 Khz input |
| RA63D | With crystal control |
| RA63E | With 455 Khz input |
| RA63F | Not allocated |
| RA63G | Ruggedised version of RA63A |
| RA63H | Ruggedised version of RA63B |
| RA63K | Ruggedised version of RA63D |
| RA63L | Ruggedised version of RA63E |
| RA63M | Ruggedised version of RA63C |
| RA98A | ISB Adaptor with AFC |
| RA98B | North American version |
| RA98B-1 | RA98B modified for all American valves, plugs and sockets. |
| RA98C | Broadcast version of RA98B |
| RA98C-1 | RA98C modified for use in Receiver Terminal RA133 |
| RA98D | High stability model |
| RA98E | RA98D adapted for use with the RA217 |
| RA98F | RA98A adapted for use with RA317. RAF |
| RA298A | ISB/SSB Adaptor for RA217,RA1217,RA1218. 3 Khz SideBand filters.Carrier re insertion from external source. No AFC |
| RA298B | As RA298A but with 5.7 Khz Filter |
| RA298C | Internal crystal controlled carrier re insertion oscillator AFC. 3Khz filters |
| RA298D | As RA298C but with 6Khz filter |
| RA298E | As for "C" but no AFC |
| RA298F | As for RA298D but no AFC |
| RA298G | Model for Australian Navy |
| RA298H | G.C.H.Q Version |
| RA298J | South African Version (10mw output) |
Updated 05/03/2002