I was thinking more along lines for amplifier switching. I have PIN diode
switches in both of my amps. There are a few AM BC stations within a few miles
of me - one is a 50 kW blowtorch and the others are 1 to 5 kW. I've never heard
any overload problems attributable to the PIN diode switches. There's only one
ham nearby (about 2.5 mi away) who can run 1.5 kW and I've never heard anything
attributable to the switches then, either. The "on" bias for the rx diodes runs
about 100 mA or so and the source voltage is 12 V.
I can't claim that they can't generate problems (kW field day ops might well
create some as might big multi-multi stations) but I can claim that I've never
encountered any.
Kim N5OP
"People that make music together cannot be enemies, at least as long as the
music lasts." -- Paul Hindemith
> On Mar 17, 2014, at 13:51, Carl Moreschi <n4py3@earthlink.net> wrote:
>
> Because relays don't cause receive overload problems when very strong signals
> saturate the pin diodes.
>
> Carl Moreschi N4PY
> 58 Hogwood Rd
> Louisburg, NC 27549
> www.n4py.com
>
>> On 3/17/2014 2:14 PM, Kim Elmore wrote:
>> Why use relays when we have PIN diodes?
>>
>> Kim N5OP
>>
>> "People that make music together cannot be enemies, at least as long as the
>> music lasts." -- Paul Hindemith
>>
>>> On Mar 17, 2014, at 11:43, "Rick - DJ0IP / NJ0IP"<Rick@DJ0IP.de> wrote:
>>>
>>> Different relays have different life cycles.
>>> AND, keep in mind that this spec was specified for a relay when switching
>>> between two STABLE STATES.
>>>
>>> If you run full QSK with the relay following the keying, sometimes the relay
>>> is in transition when it gets a command to go the other way. It must
>>> overcome inertia and change directions. THIS IS ADDITIONAL WEAR AND TEAR on
>>> the relay.
>>> THIS type of operation is not considered in the specs.
>>>
>>> Also, when Phil wrote that paper on QSK, he was referring to the open-frame
>>> relay used in ALL Ameritron amplifiers.
>>> I guarantee you that this relay will NEVER WEAR OUT when trying to follow
>>> QSK keying. . .
>>> BECAUSE IT WILL BURN UP LONG BEFORE IT WEARS OUT! (hi)
>>>
>>> UNFORTUNATELY AMERITRON IS HOPELESSLY BEHIND THE POWER CURVE WITH THEIR
>>> DEPLOYMENT OF THIS RELAY!
>>>
>>> I would remind people at this point to keep in mind that there are 3 VERY
>>> different kinds of relays used for T/R switching in the linear amplifiers
>>> that we use. The differences are HUGE!
>>> You'll find pictures and short description of these on my web site,
>>> Here: http://www.dj0ip.de/ten-tec-stuff/misc-stuff/linear-amp-relays/
>>>
>>> ALTHOUGH AMERITRON publishes a switching time of 15mS for its relays and
>>> [falsely] advertises them as "fast- nearly as fast as some QSK relays"
>>> [puke], these relays are DIRT SLOW.
>>> In reality they switch with 17 to 20mS delay, depending on the situation.
>>> *** AS MEASURED LAST WEEK BY BOB, K4TAX. ***
>>>
>>> Phil is absolutely right!
>>> (sorry Gary)
>>>
>>> NEVER-THE-LESS, there is still a way to have near QSK with the slow
>>> Ameritron Amps (without the expensive QSK-5) and still hear in between
>>> words; just not in between dit, dahs, or characters. It's just a matter of
>>> proper time sequencing. I've been doing it with these amps for 30+ years.
>>> As long as you can hear between words, there is no tangible disadvantage
>>> between QSK that can hear between dits. OK, perhaps you notice someone is
>>> transmitting when you are... 1/10 second later than with true full QSK. If
>>> you are willing to accept this, you can avoid burning the relay.
>>>
>>> In order to do this, you will need an external keyer that has adjustable
>>> time sequencing. There are a few of these on the market (i.e., WINKEY,
>>> MFJ-495, etc.) AND several rig interface boxes such as the "MicroHam
>>> MicroKeyer II" have adjustable delay (time sequencing) parameters. If you
>>> understand the timing, it's a piece of cake to set this up. With devices
>>> like that, you may use any keyer - EXCEPT the rig's own built-in keyer.
>>>
>>> 73 - Rick, DJ0IP
>>> (Nr. Frankfurt am Main)
>>>
>>> -----Original Message-----
>>> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of GARY HUBER
>>> Sent: Monday, March 17, 2014 4:40 PM
>>> To: TenTec Reflector
>>> 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 http://www.ad5x.com/images/Presentations/QSKals500als600RevA.pdf
>>>
>>> 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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