Doug,
In the newer transceivers it's different. The ANT connects to the ATU (if
installed), passes through the ATU to the LPF board, passes through the
selected LPF, then is switched with a relay to either the TX, OR the RX. It
no longer works as it did in the Triton and Argonaut.
On the RX side, the signal continues through the BPF board, through the
selected band's BPF, and just before it exits that board there is another
relay which switches between TX and RX (because the BPF is used for both
functions). On the RX side of the relay there is just a coax cable to a
small jack. At this point this line is shunted by a relay contact which
switches to ground during TX. THIS is the ultimate protection to keep RF
off of the dedicated receiver circuits.
The "hot switching" we were talking about was not within the transceiver,
but rather inside of a non-QSK linear amplifier, such as an Ameritron.
The pre-historic relays used in the T/R switching of EVERY Ameritron
amplifier that is not equipped with an expensive PIN-Diode switch option, is
very slow and burns all the time (in CW) when used with a Ten-Tec
transceiver.
We're not speaking about a loud sparking burn that can be heard or cause
significant damage; it is a very short, very weak arc that occurs all the
time as the amp's T/R relay hopelessly tries to follow the keying.
The damage progresses slowly and it can take years for the problem to become
apparent, unless you are a very heavy user, such as a crazy contester (like
me). In that case you can see the results typically within one year...
unless of course you address the problem with some means of time sequence
keying.
Time sequence keying is used to delay the RF long enough to give the
Ameritron's slow relay enough time to switch and settle in the TX position,
and also KEEP IT KEYED (hang delay) in between individual dits and dahs so
that it does not try to follow the keying.
With proper timing, it is possible to keep it keyed long enough that it does
not switch between individual dits and dahs, no between characters, but it
does switch back to RX in the pause in between words. This is the best you
can do with these amps if you want to be 100% safe from hot switching.
Modern keying circuits such as those used in K1EL's WinKey or the one used
in the MicroHam Keyer II automatically vary the hang delay with the speed
that you are sending CW, so as to always keep the keying clean, yet short
enough to hear between words. "Very elementary" (as some British OM used to
say). ;-)
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Doug Reid
Sent: Tuesday, March 18, 2014 2:15 PM
To: tentec@contesting.com
Subject: Re: [TenTec] QSK or not?
I have been following this thread for a while now, and I have a question.
First, I do not own a modern hf rig, but do operate an old Triton 544
primarily on cw. In this rig, the relay, reed relay to be specific, only
disconnects the receive antenna from the antenna input, plus it mutes the
receiver to ground during transmit. The transmitter power amp is always
connected to the antenna even during receive. I just recently replaced the
original relay with a newer, smaller reed relay I purchased from Ten Tec.
Now for my question: in the newer Ten Tec radios , are they switching both
the transmit and receive signals thru the relay, or is it similar to the
circuit in my old Triton ? How can a relay heat up if it does not switch any
high level rf ? For those of you not familiar with a Triton 544, it puts out
100w full QSK.
Sent from AOL Mobile Mail
-----Original Message-----
From: Rick - DJ0IP / NJ0IP <Rick@DJ0IP.de>
To: 'Discussion of Ten-Tec Equipment' <tentec@contesting.com>
Sent: Tue, Mar 18, 2014 02:38 AM
Subject: Re: [TenTec] QSK or not?
<div id="AOLMsgPart_1_125302e3-3c9f-45e5-ba1c-cf0f8263d1c4" style="margin:
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#000;background-color: #fff;">
<pre style="font-size: 9pt;"><tt>Excellent point on the SWR, Bob.
In fact I have never thought to monitor the SWR.
On the point with SSB and VOX being the same, yes, good point but it's not
nearly as bad on the radio as CW.
Normally when the SSB VOX triggers, it's the beginning of a word and voice
will typically start soft and ramp up in volume. Therefore the level of RF
hitting the relay is not yet 100w.
With CW, the full 100w is there with the first dit, immediately - (well
almost immediately, depending on the rise time of the signal, which is
usually about 5mS - adjustable on some of the Ten-Tecs).
However when in VOX mode, we generally work with a hang time delay, so the
RF only hits the relay too soon for the first "ahhhh", then the relay stays
switched in TX mode. Not so with CW. With CW there is no automatic hang
time (on the Eagle), adjustable hang time on the Orion and Omni VII "if and
only if" you turn it on in the menu.
So CW is beating (burning) the hell out of the non QSK relay again and again
and again under these conditions.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [<a
href="mailto:tentec-bounces@contesting.com?";>mailto:tentec-bounces@contestin
g.com</a>] On Behalf Of Bob McGraw
- K4TAX
Sent: Tuesday, March 18, 2014 1:27 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] QSK or not?
The biggest problem, as I understand, comes from operators using a non QSK
qualified amp in a QSK mode. At this point one can expect relay failure due
to hot switching.
As most amps do have the provision for monitoring SWR I suggest monitoring
the SWR indication for an indication of hot switching. After tune up
typically one will have low SWR.. If during keying one observes a higher
SWR value they can be assured that hot switching is taking place within the
amp. If this is the case, be assured the relays are taking a beating
electrically and will likely soon need attention.
Do note the same situation when operating VOX. Most radios provide some
degree of key-up delay when in CW but there is typically no delay during SSB
operation. Thus when the voice activates the VOX there is RF applied to the
amp without any delay. I find this to be a sure bet for realy hot
switching.
73
Bob, K4TAX
----- Original Message -----
From: "GARY HUBER" <<a href="mailto:glhuber@msn.com";>glhuber@msn.com</a>>
To: "TenTec Reflector" <<a
href="mailto:tentec@contesting.com";>tentec@contesting.com</a>>
Sent: Monday, March 17, 2014 10:39 AM
Subject: [TenTec] QSK or not?
I operate QSK and have the past thirty years using TenTec equipment.
One reason given by others for not running QSK is that the relays wear out
sooner in the transceiver and amplifier.
from <a
href="http://www.ad5x.com/images/Presentations/QSKals500als600RevA.pdf";
target="_blank">http://www.ad5x.com/images/Presentations/QSKals500als600RevA
.pdf</a>
How Long will the Relays Last?
What kind of life can you expect from the relays? The relay life is
specified at 100 million operations minimum at 36,000 operations/hour. The
service life increases as the operations/hour decreases. So let's use the
standard PARIS text that is used
for
determining code speed.
PARIS has 10 dits and 4 dahs = 14 relay operations/minute at 1 WPM.
Assuming an average of 25WPM code speed, you would have 360 relay operations
per
minute. So, 100 million operations = 4630 hours. Now you normally operate
50% transmitting and 50% receiving during a QSO, so your relay operating
time should double to 9260 hours. There are 8760 hours/year, which means you
could operate 1.057 years at 25 WPM before the relays exceeded their
lifetime spec - IF you operate 24 hours/day! But when you operate, you are
probably listening more like 75% of
the time
and in a QSO 25% of the time. So this says that your relay operating life
will be over 4- years if you operate 24 hours/day. So what do you normally
average in operating time/day? I bet it is not more than about an hour/day.
But let's say you average 4- hours/day of operation (i.e. you are not
married and have no kids, you don't
shop or eat
or sleep much, and you don't hold a full-time job). So the relay life will
extend to about
25 years! The bottom line - Don't worry about wearing out the relays anytime
soon.
73 ES DX,
Gary - AB9M -...-.-
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