Typical e-mail message about AR7030 IP3...

I've just purchased the AR7030 from one of your distributors in the States.
I am quite pleased with its performance. Recently a review from Kiwa
Electronics mentioning a problem with the high pass input filter
(lower IP3 at 2 MHz) has generated some concerns on my part.  My question is:
has AOR corrected the problem in later production run ? My AOR s/n is xxxxxx. Your response is greatly appreciated.

This is really a question of keeping a perspective on the issue.  So far only
a few people have ever noted the "notch" in IP3 and one was using half a mile
of wire aerial at the time.  In the worst case IP3 is still in the order of
+10 to +15 dBm across a fairly narrow range with +30 dBm elsewhere... the set
is still as good as anything else comparably or marginally higher priced
"out there" even with the SMD filter components.

As with all manufacturers AOR reserves the right to improve products where
possible & cost effective and this is what is happening to the AR7030. The
component type (not value) has been changed for the next production run with
output arriving in about 6 weeks time.

It IS possible to modify existing equipment and AOR has a policy of "open
information & support".  If equipment arrives back here at AOR MANUFACTURING
we will be happy to modify the filters for a nominal handling charge plus
return carriage.  Of course for overseas customers the shipping costs are
restrictive.  We are happy to release details for the modification but
placing leaded components onto SMD pads is not an easy task unless you are
used to handling / working with SMD each day... technically the change is
straight forward.

At this stage I am not sure what the policy of international distributors
will be.

The whole subject of IP3 has been an interesting debate but in reality unless
you have found mixing problems (related more to IP2 than IP3 anyway)
then don't worry about it... For most people BEFORE and AFTER "off air"
testing would not reveal *any* difference what so ever without top quality
test equipment being used as the measuring tool.

For your interest we keep detailed records of manufacture.  Serial number
xxxxxx was "born" on 24.7.96.  The IP2 was +83dBm and IP3 +34dBm at our test
frequency around 11 to 12 MHz.  The initial filter cals were 2.1, 5.4, 6.4 &
9.5 kHz and full I.F. /AGC calibration records are held: 92, 60, 11, 18, 7,
8, 8, 29, 14, 22 & 4.

The current production sets now offer consistent IP3 figures (within a couple
of dB) from 500kHz to 30MHz.

The "notch" with the first batch of sets was due to both inductors
and capacitors behaving non-linearly, so it is necessary to change
all of the L-C filter components. For a field modification the SM
components are replaced with leaded ones, but these need to be soldered
to the SM pads on the PCB. The existing SM components are not re-used
and are not glued to the PCB so there is no problem in removing them.

Access to the area of board involved is made easier by removing the
right-hand case side, and then unsoldering Relay RL3 (this needs some
care because of the PTH board). The relay should be replaced after the
modifications are complete.

Filter change details :-

These are all leaded components fitted with leads cut short and soldered
to the SM pads on the PCB. Inductors are mounted vertically.

Capacitors : New parts are Philips 630 series, Med-K ceramic plate (100V)
             C22      1n8  10%
             C23      1n0  10%
             C24      1n8  10%
             C25      2n2  10%
             C26      3n9  10%
             C27      2n2  10%

Inductors  : New parts are Siemens B78108-T series (axial leaded)
             L8       3.3uH  10%
             L9       3.3uH  10%
             L10      6.8uH  10%
             L11      6.8uH  10%


AOR will be happy to supply a kit of these parts if you cannot obtain
them locally. Please contact Richard Hillier <richard@aor.co.uk> if
you need them.

I must emphasise that this is not an easy modification, and requires some
skill with a soldering iron to do a good job.

Best regards and good luck,  John.  <jt@aor.co.uk>
