I know nothing about the TR7, but I searched the web for "drake tr7 output
power adjustment” and found this useful-looking page, with photos.
http://www.wb4hfn.com/DRAKE/DrakeArticles/TR7_ALC_Control/TR7%20ACL%20Control.htm
I hesitate to answer to this, it's been so
long since I had a TR7 (My 2nd rig) and my
memory of it is not clear.
Given this disclaimer, I believe you'll
find an adjustable piece, two wafers with
a rectangular key hole in the center part
to turn it. Cap or resistance, I don't
recall what it
It's worthwhile noting that either adjusting the internal ALC to limit
power or providing some external means to control it is really quite
essential with some of the early solid state and certainly many of the
hybrid radios. Most of these radios had NO proper power control in SSB.
Whilst the
Marcel,
About the maximum voltage, that might be in the TR7 specifications.
OTOH, start with the pot at a low voltage and increase it until you
achieve the results that you want.
The K3 EXT ALC default threshold is -4.0 volts, so that may be a good
starting point for your experiments.
73,
Thanks to all of for your prompt answers
On CW it works great thanks to the carrier adjustment control
On SSB: it goes to 150W out very easy
Yes it is just for fun.
The K3 is great but the TR7 is funny and special.
One last question: Someone suggested to use a 9V battery with a pot to inject
Drake rated the TR7 by input power as was common then. 250W. They recommended
a fan kit for high duty cycle RTTY operation.
I owned one for years and it was a wonderful radio. The only issue was
tin-plated pins (sound familiar) on the interface between the main circuity and
the digital
As an aside on the TR-7 (one of my all-time favorite radios), Drake generally
limiting output power to about 120W (adjusted on 20M) to keep the PA healthy
long term. While the PA is capable of 150-200W output, it was certainly not
recommended.
As to cooling, there was an optional fan to cool
Hi again,
I totally mangled the 2nd statement. Corrected below.
Knut
ab2tc wrote
> Hi again,
>
> True, but the TR7 is all solid state, including the finals. See here:
>
> http://www.wb4hfn.com/DRAKE/DrakeArticles/InsideTheTR7/Inside_The_TR7-01.htm
>
> According to that article Drake claims
Hi again,
True, but the TR7 is all solid state, including the finals. See here:
http://www.wb4hfn.com/DRAKE/DrakeArticles/InsideTheTR7/Inside_The_TR7-01.htm
According to that article Drake claims 130-150W output for bands at above
20m and 60-100W on 80-15m.
Boy, is that transceiver ever
On 1/13/2019 12:35, ab2tc wrote:
With typical efficiencies seen in solid state PAs it is probably rated at no
more than 100W output,
Actually, tube amplifiers can be quite a bit more efficient than solid
state ones. The theoretical limit for class B is around 70 percent, a
practical limit
Hi Marcel and Don,
The TR7 is rated at 250W *input*. See here:
https://www.universal-radio.com/catalog/hamhf/tr7.html
With typical efficiencies seen in solid state PAs it is probably rated at no
more than 100W output, so the KPA500 should give you noticeably more power.
Anyway, Don's suggestion
Marcel,
Can you add a "Power Control" to the TR7?
It may be as easy as applying a constant negative voltage to the ALC
input. That constant ALC voltage will not cause the problems
encountered when using the dynamic ALC voltage that is applied from the
amplifier.
73,
Don W3FPR
On 1/12/2019
Hello EA3IN,
There is a 1 kilowatt solid state amplifier, using NXP 188 final power
transistors, built in England.
Please see LinearAmp company, model Gemini HF-1K amplifier. I believe
that DXshop is the
vendor. Regards, bp. K2AYA.
On 1/12/19 12:59 PM, Marcel Jorba via Elecraft wrote:
If you can run 200 watts PEP with the TR7, why run a 500 watt amp?
Otherwise, you'll need a 10dB attenuator between the TR7 and the
KPA500. Hence turn 180 watts of RF from the TR7 into heat as it takes
only about 20 watts to drive the KPA500 to rated output.
73
Bob, K4TAX
On 1/12/2019
Greetings from Barcelona
I have here a K3-KPA500 setup that runs great
I also have a TR7 and I am thinking about using it together with the KPA500 The
obvious problem: The TR7 delivers a lot of watts (200 pep).
Is it an idea to discard? Or is there any reasonable approach to? ALC control
is not
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