[Premium-Rx] Eddystone 1650/9 relay problem.

[Carcia, Frank A. HS]

Gee,
Motorola used a reed relay in an older radio if I remember. It was in a
glass tube about 3/16 diameter and about an inch long tube.
                                                                    fc

-----Original Message-----
From: GandalfG8 at aol.com [mailto:GandalfG8 at aol.com]
Sent: Wednesday, August 06, 2003 2:59 PM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] Eddystone 1650/9 relay problem.


Hi All

This is a brief tale, well I'll try to keep it brief anyway:-), of a problem
solved that I felt might be helpful to other Eddystone 1650 owners on the
list.

I recently bought a 1650/9 in lovely condition. It passed all its BITE tests
but, other than a couple of strong broadcast signals, was as deaf as a
post..
A quick look at the schematic showed that BITE tests are carried out with a
noise injection oscillator right at the front of the RF stages.
The only sections not in the BITE path are the protection circuits and some
attenuators etc in the antenna line with a bunch of relays to switch them so
that seemed like a good place to start.
It didn't take long to establish that two out of five changeover relays of
one type were effectively open circuit in the normally closed position. The
main culprit was the relay that switched the RF input between the BITE
oscillator and the antenna circuit.

The relay in question is a Hamlin type HE321C1200. It's a circuit board
mounted reed relay with, in my case anyway, a yellow covered central coil
marked with the part number and the glass enclosed reed mounted inside that.
I assumed at first that the problem was tarnished contacts but it seems like
it might be more mechanical and possibly due to some distortion even though
the glass was unbroken. I found that slight pressure on the NC lead would
restore contact. A bit more pressure than intended and the lead bent.
I thought I might have finished it off completely but it started to work ok
again!!
We all need a birt of luck sometime:-)

I'm not recommending this as a fix:-) and still want to source enough relays
to replace all in the set, I've found at least two more on other circuit
boards, but at least the set is working for now.

Anyone suffering the same problem om a 1650/9 would no doubt find it as easy
to diagnose as I did but it might not be so obvious in earlier sets without
the BITE oscillator to provide a clue.

I don't know if these relays were used in other models but thought I would
share the experience just in case it does prove useful to anyone else.

As far as I can tell this relay is now obsolete....
there's a surprise:-)
I haven't checked fully yet but a search on the Hamlin site earler seemed to
indicate that one US distributor at least had around 6,000 in stock. That
seems to good to be true, and might be, but I'll try and contact them later
and confirm that it is the same relay.
If anyone's interested contact me off list and I'll pass on whatever
information I get.

regards

Nigel
G8PZR

PS
Once it's up and running it's one heck of a nice radio:-)



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