[R-390] Greetings from Sydney, Australia.

[Eric Gauja]

Dear Group,
                       Having recently acquired a 390A,  and discovered this group, I would like to introduce myself.  I’m Eric Gauja , almost 62 years old, live in a suburb of Sydney ,Australia,  and my main hobby interest is communications receivers and shortwave listening. Before my retirement 2 years ago ,  I worked in an MOS Integrated  Circuit Fabrication Facility at the University of NSW as a semiconductor fabrication engineer,  so the hollow state 390A circuitry is at the other end of  the size spectrum! – but because of my advancing years/ degenerating eyesight,I still need a magnifying glass to see clearly into a lot of the 390A’s circuitry.  Interest in electronics and radio goes back to my teen years, but in those days communications receivers were way out of my reach moneywise  -  I just looked longingly at all the ads in the magazines, and had to get by on simple homebrew.  Now I have more time and a bit more money ( and the $A is worth more than the $US! ), so I spend my hobby time acquiring communications receivers, testing them out, perhaps doing some repairs and sensible modifications, and then selling them again to finance another purchase! Over the years I have had Yaesu FRG 7, 7700, 100 ,  Kenwood R5000, R2000, R1000,  Icoms R70,R71, R75,  AOR7030,  WJ 8709,  Racal RA117,  RA6217 , AWA CR6B , and Edddystone 680X.     I have also dabbled in Software Defined Radios such as the Winradio G303 and SDR –IQ , but am put off by the computer interface , and could never solve properly the problem of RF interference from the digital circuitry raising the local noise floor.   I know there are techniques for suppressing digital noise, but in my experience ,any communications receiver will receive some noise from a nearby computer and switchmode power supply.  My computer is in a different room to my receivers.
                      Currently , I have an Imperial Electronics R390A  (s/n 2304) that I bought at the end of last year from another list member , Pete Williams.   Getting a 390A had long been my intention – they are not too commonly sold in Australia, and Pete had a very nice refurbished unit on offer here in Australia.  I am enjoying it immensely,  and am glad to see that information on the care and feeding of R390A’s is plentiful – I started off with the R390A FAQ page , and then after a blind alley with the 390 Yahoo group finally discovered this mailing list.   I am currently systematically going through the archives to get an idea of what questions have been asked in the past, so as not to bother the group with things that have been dealt with before. I have invested in a set of Bristol Keys from the US (unobtainable in Australia).   I have also found  that Fair Radio has a good supply of bits and pieces for the 390A – I have replaced some crystals with their stock , and found their service to be excellent.  So I am now happily evaluating the 390A.  I have 2 other radios that I use for comparison purposes – a recent Icom 7410 , as an example of a decent contemporary receiver , and a small portable Tecsun PL660, which received a very good review in the 2012 edition of the World Radio TV Handbook.
                   
                      Generally, I am very pleased with the 390A.  I do have 2 initial questions that I would like to put to the group.   
1)  AGC performance.   It seems that my R390A needs a relatively high value of input signal before its AGC activates, and the Carrier Meter moves.  I note that in the AGC circuit description in the technical manual it states that the AGC circuit operates only for signals in excess of 5 microvolts – this to me seems to be quite a high signal level  for a communications receiver,  and in general listening to non local stations, the R390A does not use its AGC circuit.  I have zeroed the Carrier Meter , and the IF gain pot is set to  midway, so it is not  a case of my 390A having excessive IF gain.  Is this normal , or do I have an AGC fault?

2) Calibrator circuit .   What sort of variation should be expected in the Carrier Level Meter reading for different calibration frequencies?  Calibrating  my 390A at frequencies XX.700 MHz gives zero beat Carrier Level Meter dB readings  of between 20 and 30dB in the 0 to 15 MHz range.  At 16.700MHz the reading drops down to only 0dB,  (although the signal off zero beat is still easily audible). From 18.700MHz to 24.700MHz , the carrier level at zero beat stays at 0dB.  It goes back up to 10 dB until 29.700 MHz, before dropping down to 5 and 0 at  30.700 and 31.700MHz. I have checked the RF deck alignment using the procedure outlined by Dallas Lankford in Hollow State Newsletter 29 , and it seems fine.

Thank You for accepting my group membership, and I look forward to sharing my 390A experience with you all!
Best Regards,           
                        Eric.