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W3TDH

200 Watt Output Transceiver?

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Posted (edited)

I was saving up to buy a Kenwood TS-480HX 200 Watt output transceiver for EMCOMM use. I wanted the 200 Watts so that I  could get ~60 Watts out at 100% duty cycle such as when sending a lot of information digitally from a disaster recovery operations site. Now that Kenwood has discontinued the TS-480 I need another way to get a similar output. As far as I can tell there is no transceiver currently offered new that has 200 Watts output. Does anyone know of one that makes that wrong? I'm reluctant to consider carrying along an amplifier but that may be the only way to get the output power I want. 

--

 

Tom Horne W3TDH

Edited by W3TDH

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EXPERT ELMER

Hi Tom.

That I know of, the main readily available option is the FTDX101MP. It pumps out 200W.

I've finally gone another route. I just installed an RMItaly 305V amplifier. What I really like about it, and I'm not the only one, Alan and James use it as well, is that it can pump out upwards of 300W with only 10W in, which is far far better than the Ameritron option. I have the whole thing set up in my car. I'm currently exciting it with a Yaesu 891, but if the new Icom 705 QRP and QRPp rig turns out to be good, I might switch it out. The 705 puts out 10W which happens to be the max allowable input into the RM Italy 305V. Price-wise, you'll come out at the same cost.

Of course, the only problem is size and weight. The 480 was acceptably compact for a 200W rig. Neither the Yaesu 101 solution, or any exciter plus the linear will be that size. So the question is really whether you're looking to install it in a 'box' or built into the vehicle, as I have it. This said, both Alan and James have built the 305V into boxes. If you decide to explore that route, I'll get @W4DOI and @W3JRD to post some images of their boxes.

Hope this helps.

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Jim

The idea would be to build it into a transportable station. That way one could turn it on whenever the digital output power is needed. I would welcome seeing those stations!

Now how would you protect it from a possible outbreak of stupid? I don't want to throw 100 Watts into the Amplifiers input and jail break the magic smoke. As I'm sure you have observed once the magic escapes the device in question has to have it's magic smoke replaced before it will work again.

Is there, for instance, an attenuator that can be switched in or out in the pathway to the amplifier that would prevent my frying the input with the transceiver's full 100 watts. That could be connected by an electrically operated antenna switch so that when I turn the amplifier on it transfers the feed line to the attenuator. I go to transmit and, because of the amount of attenuation installed, I see a different output level than I expect. I realize my mistake and correct the transceiver's power out. Then I could switch the power to the antenna switch coil off using a self sealing relay When the control relay is energized by the operation of a momentary switch, which connects the amplifier’s DC power supply to the relay, it would open the control pathway to the antenna switch and close a pathway to the control relay's operating coil so that when I release the momentary switch the relay will hold itself closed. The control relay will remain energized until I manually open it’s coil control current or the operating power to the Amplifier is turned off. Since the control power for the relay and the antenna relay both come from the same power lead; which supplies the amplifier, the antenna switch, and it’s control relay both the control relay and the antenna switch would return to their normal states ready to begin the process again the next time I switch on the amplifier DC supply lead.

I’m sorry but I don’t know how to draw a ladder diagram, that illustrates the control pathways through a control circuit, on the computer.

I would be running the amplifier at 1/3 it's design maximum for actual operation. and what I would see upon testing would be closer to full output. I realize my mistake, reduce the transceiver outlet to the value I need and after repeating the test I would open the manual momentary switch to drop out the relay and thus drop the antenna switch there by taking the attenuator out of the transmit pathway.

--

Tom W3TDH

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EXPERT ELMER
Posted (edited)

Hi Tom. It's actually far easier than you think. For one, the RM Italy 305V won't fry, it'll just cut at 10W in. If you give it 11 W, it cuts, period. I'd love to show you how I have it wired up in my car, it's sweet. I have two buttons labeled QRP and QRO. The QRP just PTTs the TXC. When the amp does not receive a PTT, it just lets the signal bypass, so I can tx up to 100W without the amp. If I want to go QRO, I reduce my TXC power to 10W and hit my QRO button which activates both my TXC and my RM Italy... sweet. I'm actually going to transmit my first car signal this Saturday at 8:30 AM from Gaithersburg. I'll be getting on 80M to join the Cherry Tree Net (regional net on 3920).

If you'd like to see my setup, glad to meet up (social distancing, of course). Otherwise, I can take some photos and show you. As for shots of Alan and James' rigs, I think we have some on the site somewhere. I'm going to look for them. I'll also ask @W4DOI and @W3JRD to post some of their own, if they have any. In their case, they drive the amp with a 7300. I used to, but I sold it. Like I said above, I'm thinking of testing out the Icom 705 when it finally arrives.

**Edit**

Here you go. Alan's is the first setup, and James is shots two and three.

large.1879986880_assateague2019-1.jpeg

large.k3mri-image-00028.jpg

large.k3mri-image-00008.jpg

Edited by K3MRI
Inserted photos
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On 7/2/2020 at 3:25 AM, K3MRI said:

Hi Tom.

That I know of, the main readily available option is the FTDX101MP. It pumps out 200W.

I've finally gone another route. I just installed an RMItaly 305V amplifier. What I really like about it, and I'm not the only one, Alan and James use it as well, is that it can pump out upwards of 300W with only 10W in, which is far far better than the Ameritron option. I have the whole thing set up in my car. I'm currently exciting it with a Yaesu 891, but if the new Icom 705 QRP and QRPp rig turns out to be good, I might switch it out. The 705 puts out 10W which happens to be the max allowable input into the RM Italy 305V. Price-wise, you'll come out at the same cost.

Of course, the only problem is size and weight. The 480 was acceptably compact for a 200W rig. Neither the Yaesu 101 solution, or any exciter plus the linear will be that size. So the question is really whether you're looking to install it in a 'box' or built into the vehicle, as I have it. This said, both Alan and James have built the 305V into boxes. If you decide to explore that route, I'll get @W4DOI and @W3JRD to post some images of their boxes.

Hope this helps.

Isn't the FTDX101MP that huge contesting rig with the built in panadapter that weighs in at nearly 30#? Not exactly an EMCOMM friendly rig.

What I didn't see in your answer is how I reduce the workload on the radio / amplifier combination that you are talking about so that the 2 used together will stand up to modes that cause a near 100% duty cycle. 10 watts output on a Yaesu FT-857 is great but doesn't that leave the amplifier running at full rated power output? That would not be likely to stand up to a very high duty cycle.

Does anyone know of an amplifier that takes a wider exciter power range and varies the output power with the exciter power. I want to have both the transceiver and the amplifier running at not more than ~1/3 of their respective maximum power output.

I already have the Yaesu FT-857 radio. I think that it's form factor is a very good choice for EMCOMM.

My plans include a remote antenna coupler, rather than an antenna tuner niether in the radio nor at the operating location. With me it's nearly a religious tenet that you match the feed to the antenna rather than matching the transmitter to the feed line. The other thing that makes me avoid using antenna tuners which are part of the Transceiver is that the range of Impedance which they can match is much lower than an external tuner or a remote coupler.

Repeating I want the combination to be able to run at 1/3 of it's maximum output so that it will better put up with a higher duty cycle that approaches 100%.

--

Tom W3TDH

Edited by W3TDH

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EXPERT ELMER

Hi Tom. Can't give you ⅓ duty cycle, but about ½. Alan and I managed to, with SSB, get 400 Watts out of the RMItaly. So 200 Watts would be comfortable. Note, also, that we tested the James' RMItaly last year during the VA QSO Party and were running all day at full power with insane pile-ups. If you'd like, I'd be glad to show you the setup at least. I could drive and meet you somewhere one of these days.

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The TS-480HX is what I was saving up for when Kenwood dropped the 480 model line. My concern is that buying a modal that has already been discontinued would mean that service or parts support would be unavailable rather soon. That is why I though that an amplifier with a wider range of drive wattage that would reduce the amplifier output as the drive power was lowered might be a good answer. With the right drive range a 300 Watt amplifier could coast along quite happily at 100 watts output and 100% duty cycle.

--

Tom W3TDH

Edited by W3TDH

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