Dave...
Well, its not rocket science! Some amps can be direct keyed by some
rigs...and some cannot. To find out, first read through both manuals and see
if they offer any specs as to the keying requirements. I use to key my L7
with my TS850 directly, but I would not key any Heathkit amp. They have more
'juice' at the terminal!
Another thing you can do is jam a multimeter into the 'key' jack of the amp.
Set your meter for current, then set it for voltage. You don't even have to
touch the leads (as long as you don't have to spin the meter knob through
resistance!!) You will get both the voltage at the terminals, and the
current when keyed.
If it turns out you are border line, and need a relay....What I did was
purchase a small 12 volt coil relay from radio shack...along with the small
blue project box, a handful of RCA phono jacks, and some wire. I wired the
key terminal in series with the 12 volt on transmit of the rig to the coil
on the little relay, and the little relay contacts go to the amp. If you
don't have 12 volts on transmit from the rig (or even 9) you can then use a
little wall wart, and let your rigs keying line switch that to the little
relay to key the amp.
The whole thing boils down to how 'beefy' is the amp in your rig. I don't
know what the Jupiter has. You used to be able to key anything with a SB102,
or TR4. I think even an old TS520 is up for the task. But....a 756Pro series
cannot be hooked up to anything without an external relay. Yaesu even sold a
product just for keying an amp...an FRB7...which is as explained above...a
box with a relay in it.
Sometimes it is suggested to put a diode in there to squash any back emf
from the amp relay when it unkeys....but, I never bothered with that and
have not had a problem.
Your tuner will be on the output side of the amp. Tune it up with the amp
off. Then, the amp will also see a fairly low SWR when you turn it on. Best
to use the SWR meter in the amp (if it has one) as that is what the amp will
see. Because of jumper cables to the rig, the rig may not see the same SWR,
but it will be low enough.
Glad to help if you have any questions!
Good luck.....Dave
----- Original Message -----
From: "Dave Tipton" <dave@lodave.org>
To: <tentec@contesting.com>
Sent: Sunday, March 26, 2006 9:29 AM
Subject: [TenTec] Hooking up an Amplifier for the first time...
> Ok, so I'm a total novice at running anything other than a barefoot rig.
> I was at the Weatherford, TX hamfest yesterday and picked up a Dentron
> GLA-1000 amp with some extra tubes, yadda yadda yadda.
>
> As I was reading through the manual, on how to hook up a amp to my
> jupiter, I saw a strong word of caution about using older tube amps and
> their relay circuits... What I decided, was, instead of being sorry, I'd
> be safe.. I'd build a relay circuit that when the Jupiter amp connection
> closes, I'd key the amp. Seems reasonable right? I know there is a low
> amount of power coming out of the jupiter, enough to key the relay? I
> don't know.. (PArt 1 of the question)
>
> Part 2 -
> I started looking around on the web to see if there was anything out
> there that might provide additional functionality, etc. (Why?? I have NO
> idea) Now I'm seeing that there are tons of "Delay" circuits out there
> that hold the amp keyed down for a few extra seconds.
>
> Anyone care to elaborate on this? Can I just wire up a relay, get the
> power for the relay from the output on the Jupiter, and then when I unkey,
> it comes back and I hear receive noise again?!?! I'm so confused...
>
> Last part of the question...
> Can I reliably tune my antenna (Not using the internal auto tuner) and
> then bring my amp in line? (I picked up a 3KW tuner to go with this. A
> dentron MT-2000A) What I'm thinking, is put the amp in standby mode, tune
> my longwire/dipole/etc, then bring the amp in line, tune up the amp and in
> theory this should prevent me from blowing up my amp. Since I don't have
> a 500 Watt Dummy load, it's the best I can do for the moment.
>
> Sorry if this seems a little off topic, I know some of it is directly
> related to the reflector, but I appreciate help on the other sections too.
>
> Thanks,
> Dave - A newbie at 20 years, once again
> W3DMT
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> TenTec@contesting.com
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