Collins 651S-1 Question - Retaining Frequency
Jeff
the radio is turned off? Now I get ".0000" each time I turn the radio
on, regardless of what frequency I was tuned to when I turned it off.
A youtube video shows the radio coming up tuned to 20 meters when it
is turned on: how is this implemented?
I added a 6 VDC source to the terminal strip on the back, and that
retains the frequency when I unplug the radio, but when I turn it off
using the power switch it still comes up .0000 when I next turn it on.
73,
Jeff
N6MNI
WA4VZQ
-dd0d-415c-b1b...@u18g2000pro.googlegroups.com...
From the website, http://www.collinsmuseum.com/651s1.html:
"FREQUENCY MEMORY KEEP-ALIVE POWER
Used to maintain storage of frequency information during power
interruptions. An external 6- to 8-volt battery supplies the necessary
power for the circuit. This option is implemented by wiring the special
keep-alive assembly into the chassis subassembly. Refer to the
configuration chart for status numbers of receivers that include this
option and for the part number of the chassis subassembly that includes
the special keep-alive power assembly."
73, Barry WA4VQ
Dave Heil
That's the skinny. We used a rack of four of them at the U.S. Embassy
in Guinea-Bissau in 1987-89. Each had been modified by having its blue
fluorescent displays replaced with LEDs. The receivers each had had a
6-volt gel cell. All the gear was replaced by Harris equipment shortly
after I left in September, 1989 and was replaced by Harris equipment.
Jeff
> WA4VZQ wrote:
> > Jeff, N6NMI, <the-dha...@sbcglobal.net> wrote in message news:ce12ab6a
> > -dd0d-415c-b1b9-694ca342c...@u18g2000pro.googlegroups.com...
> >> Is there a 651S-1 mod that retains the last listening frequency when
> >> the radio is turned off? Now I get ".0000" each time I turn the radio
> >> on, regardless of what frequency I was tuned to when I turned it off.
> >> A youtube video shows the radio coming up tuned to 20 meters when it
> >> is turned on: how is this implemented?
>
> >> I added a 6 VDC source to the terminal strip on the back, and that
> >> retains the frequency when I unplug the radio, but when I turn it off
> >> using the power switch it still comes up .0000 when I next turn it on.
>
>
> > "FREQUENCY MEMORY KEEP-ALIVE POWER
> > Used to maintain storage of frequency information during power
> > interruptions. An external 6- to 8-volt battery supplies the necessary
> > power for the circuit. This option is implemented by wiring the special
> > keep-alive assembly into the chassis subassembly. Refer to the
> > configuration chart for status numbers of receivers that include this
> > option and for the part number of the chassis subassembly that includes
> > the special keep-alive power assembly."
>
> That's the skinny. We used a rack of four of them at the U.S. Embassy
> in Guinea-Bissau in 1987-89. Each had been modified by having its blue
> fluorescent displays replaced with LEDs. The receivers each had had a
> 6-volt gel cell. All the gear was replaced by Harris equipment shortly
>
> - Show quoted text -
Hmmm; so with the 6 VDC source connected, when I turn off the power
switch, and turn in back on, I should see the same frequency displayed
as when I turned it off? I'm not seeing this behavior with my radio;
if I unplug the power cord from the wall, and plug it back in, this is
the way it works, but if I cycle the power using the panel mounted
switch, I get ".0000".
Richard Knoppow
"Jeff" <the-d...@sbcglobal.net> wrote in message
news:a984d860-158a-4f0c...@u36g2000prn.googlegroups.com...
I am not at all familiar with this receiver but is it
possible that the power switch is also a reset switch? If it
is perhaps its possible to disable the reset function.
--
Richard Knoppow
Los Angeles
WB6KBL
dick...@ix.netcom.com
Dave Heil
That sounds normal to me. We left our receivers on 24/7 and the battery
just kept the thing from doing going to .0000 if the commercial power
failed--and it did that quite often. We had no automatic changeover to
generator power and had to go into a generator room and manually fire up
the 40 KVA generator. It would have been ugly to have to retune the
receivers after all that.
Jeff
>
> - Show quoted text -
If you go here:
http://www.youtube.com/watch?v=708FBf6t87c
the operator turns the radio on, and it comes up at 14.000 MHz. So
apparently is is possible for the receiver to remember the last-tuned
frequency when turned off/on using the power switch. The question is,
how?
Perhaps a clue will be provided by the service manual, which I'm
trying to locate. $urplus $ales of Nebraska has one, but they're
asking in my opinion too much money. There is also a service bulletin
(which I have) that addresses a "frequency keep-alive" modification,
but I'm reluctant to tear into the radio to the degree required to
implement the modification until I have a manual/schematic. The
language in the bulletin is somewhat terse and I'm not even sure this
mod will give the behavior I seek.
I like Richard's idea: I'll get the Service bulletin out and
paraphrase it here. Perhaps the mod does indeed defeat some sort of
power-up CPU reset...