Jim Weir - Radio Receive Current

[Ron Wanttaja]

Nothing earth-shattering, just an idle curiosity. Several years ago, I had to
replace the Escort 110 in the Fly Baby with a radio that met the tightened FCC
frequency specifications. I bought a heavy-duty power supply from Rat Shack to
power it, and it now lets me listen to CTAF in my den. When I was
trouble-shooting the replacement radio last summer, I brought the 110 down to
the airport to set up a tape recorder to check how it sounded when I was in
flight.

It sat idle since then, until I decided to bring it home. I thought I could
maybe replace the big power supply with a wall wart...I've got one rated about
1.2 amp at 12VDC. I figured that should be enough for a receive-only setup, but
exercised the better part of discretion and decided to measure the actual
current draw.

The result surprised me: About 2 amps, in just the COMM receive mode. Squelch
up, squelch down didn't seem to make much difference.

I admit this is an old radio, but it *is* solid state (no tubes). I didn't run
it for long, so didn't even find out if it actually still receives.

Does this seem normal for DC current just during receive?

The Escort 2 I replaced it with is rated just 0.5 amps during receive, and the
ICOM IC-A5 that replaced *that* runs for hours on a set of AA batteries. Were
those first-generation solid-state radios really that inefficient?

Ron Wanttaja

[Tater Schuld]

"Ron Wanttaja" > wrote in message
...
>
> The Escort 2 I replaced it with is rated just 0.5 amps during receive, and
> the
> ICOM IC-A5 that replaced *that* runs for hours on a set of AA batteries.
> Were
> those first-generation solid-state radios really that inefficient?

yes. back then no one thought about power efficiency.

[karel]

"Tater Schuld" > schreef in bericht
...
>
> "Ron Wanttaja" > wrote in message
> ...
>>
>> The Escort 2 I replaced it with is rated just 0.5 amps during receive,
>> and the
>> ICOM IC-A5 that replaced *that* runs for hours on a set of AA batteries.
>> Were
>> those first-generation solid-state radios really that inefficient?
>
> yes. back then no one thought about power efficiency.

It is true that power-efficiency wasn't a prime design factor
before the 90's or so. Even so, it would really take a lot of
bad sense to design a solid state nav TX drawing 2 amps
(that means 25 watts!) in rx standby or even active mode.
So, unhindered by much factual knowledge, I tend to agree
with O/P, somethings's wrong somewhere.

Humbly from continental Europe,
Karel.

[Ron Webb]

>>> those first-generation solid-state radios really that inefficient?
>>

Around 1978, I was given the job of modifying a Motorola Land Mobile (FM
~150MHz) repeater for use on a mountaintop repeater site where we were
installing solar power. The idea was to see how much current we could save
with simple modifications.

I found that when you turned the speaker off with the little plastic slide
switch provided, it actually SHORTED the output of the audio transformer.
Shut the thing up - sure did! So 90% of the standby rx current was being
drawn by audio circuitry - just because the design people had been too cheap
or lazy to do it right. And this was on a fairly modern (by aviation
standards) radio that was worth $5000 or so, even back then.

I moved the switch so that it cut power to the audio instead of just
shutting it up - and the size of the panels needed dropped by half!

You said they didn't care about current draw. That may have been an
understatement!