An Intresting Idea, what do you think about this mobile setup???

[dxhound]

Ok, So I am pondering installing a TS 1600 in my truck. But I still want 80-10 meter capability. So I am going to probably get a kenwood TS 480hx/sat. NOW, we all know that without filtering, on the Ham bands I will stick out like a sore thumb. So I got looking at band switch designs and filter networks and noticed somthing VERY perculiar. These desighns look VERY similar to LDG/MFJ Auto tuners. The way they use a series of capacitors and inductors to match the SWR leads me to believe this is also a fairly good band pass filter.
Now If I got the 480sat with the built in tuner, that would eliminate the need for an input filter since the radio can match the amplifier input. Then I should be able to put a legal limit tuner between the TS1600 and an antenna(prob a whip style) and match the standing wave. It would be a perfect setup!

Keep in mind, I dont drive the snot out of my stuff....800 watts peak would do me fine until I get another TS 1600 and make a viking 3200!!!


What do you think about this.......It seems very doable looking at the tuner scheamatics and how they are setup.

 

[BOOTY MONSTER]

i dont know much about amps , but i think the filtering is gonna be no problem at all compared to the problem of the amp not having the bandwidth to operate across the bands/frequency range you want to use it on .

Texas Star CW Transmitters

"Frequency Range 28.0 MHz to 29.7 MHz "

i know it will go out of that range because folks folks convert them to do more than CW mode and use them on 27MHz . concerning how far though my deer have no eyes .

hehehe "Power Output < 5 watts"

 

[n8fgb]

Just get aN ALS 500m, and not worry about all the other junk.
Rich

 

[Captain Kilowatt]

Just get aN ALS 500m, and not worry about all the other junk.
Rich

Agreed. Besides an antenna tuner makes for a really poor filter. It may reduce some harmonics but will do nothing for in band IMD. In some cases an antenna tuner offers no filtering whatsoever to the frequency you wish to eliminate.

 

[BOOTY MONSTER]

Just get aN ALS 500m, and not worry about all the other junk.
Rich

good call . going from 800 watts to 400 watts will never be noticed in the real world .

Ameritron

 

[dxhound]

I have looked at these before, and after digging around, I found they use a pretty simple input filter that is a band pass and the output is your every day lowpass filter, not a bandpass filter. This would be easy to make. I know the simple solution is buy the ameritron.....but arnt we radio enthusists!!

 

[W5LZ]

The only similarity between a tuner and a filter is that they both use inductors and capacitors. After that, the similarity comes to an abrupt halt, entirely different circuits with different purposes. A decent hi/low/bandpass filter will have more than one 'stage' of filtering, that tuner only has one 'stage' which is changing impedances, not really 'filtering' anything. That tuner will let anything through that the transmitter happens to transmit. Or that the antenna 'hears' and sends to the receiver.
Nice idea, but 'fraid it doesn't describe what's happening with tuners versus filters.
- 'Doc

 

[dxhound]

The only similarity between a tuner and a filter is that they both use inductors and capacitors. After that, the similarity comes to an abrupt halt, entirely different circuits with different purposes. A decent hi/low/bandpass filter will have more than one 'stage' of filtering, that tuner only has one 'stage' which is changing impedances, not really 'filtering' anything. That tuner will let anything through that the transmitter happens to transmit. Or that the antenna 'hears' and sends to the receiver.
Nice idea, but 'fraid it doesn't describe what's happening with tuners versus filters.
- 'Doc

But arnt the band pass filters in these "broad"? By that I mean they allow a freq to pass within the entire band 3.5Mhz-3.8Mhz They dont really target a fundamental freq and attenuate anything thats 3khz either side of it. They just attenuate harmonics that are out of band. The slopes on these kind of filters are not very sharp. I figure it like this. Have you ever used a tuner on 40 meter then ran down to 80 meters and everyone is real quiet? S5 or s8's, then tune the tuner for 80meter and bam s9-s20. That because the tuner was attenuating the freq that it was not tuned to.

Maybe Im off on my thinking, But I will look deeper into this as it would make one kick ass KW amp if it had band switching!!!!

 

[W5LZ]

The same would happen if you didn't have a tuner at all and just an antenna for the wrong band.
So it would -seem- that the tuner may be a 'filter', but it isn't. Unless you'd figure an antenna for the wrong band would be a 'filter' too? I would think you would also get the same affect if you just rolled the RF gain back a ways, right? Same affect, but not a filter.

But, I would agree that an amplifier with tuned output circuits, rather than the common "no tune" circuits would definitely have benefits. But then, you'd have to turn a knob! Eeuu, nasty habit!
- 'Doc

 

[dxhound]

HF Projects - Low Pass Filters

For the input!

 

[bob85]

most atu's like the mfj's are highpass , hf pa filters are often double pi/ halfwave low pass,

you can't just stick filters on any old cb amp and expect decent performance over many bands, it may work depending on the amp you choose,
rmitaly get away with doing just that on their hf amps but they don't act like a real hf amp having far too much gain at low frequencies and can be provoked into self oscillation on certain frequencies and drive levels,

the amp should be designed for the job and unlike rmitaly preferably unconditionally stable,
suitable ferrite, lcr negative feedback networks or another topology to flatten the frequency dependant gain curve of bipolar transistors and minimise impedance excursions,
they should also have a tracked regulated bias circuit,

you may get a sweet 16 to operate on hf but i wager to make it work right needs more than filters,

filters only work as they should when terminated with their design impedance,

i think mole and justin had a play with texas stars on hf,

good luck

 

[-=PEAKABOO=-]

Agreed. Besides an antenna tuner makes for a really poor filter. It may reduce some harmonics but will do nothing for in band IMD. In some cases an antenna tuner offers no filtering whatsoever to the frequency you wish to eliminate.

Are you saying they make a filter for in band IMD or that the ALS will have less IMD than the TS amp?

 

[-=PEAKABOO=-]

You are right Bob, they will transmit on most of the HF band but they are crap. They need a lot of work to work correctly. I am not talking about filtering I am talking about the issues with oscillation and crummy bias design.

most atu's like the mfj's are highpass , hf pa filters are often double pi/ halfwave low pass,

you can't just stick filters on any old cb amp and expect decent performance over many bands, it may work depending on the amp you choose,
rmitaly get away with doing just that on their hf amps but they don't act like a real hf amp having far too much gain at low frequencies and can be provoked into self oscillation on certain frequencies and drive levels,

the amp should be designed for the job and unlike rmitaly preferably unconditionally stable,
suitable ferrite, lcr negative feedback networks or another topology to flatten the frequency dependant gain curve of bipolar transistors and minimise impedance excursions,
they should also have a tracked regulated bias circuit,

you may get a sweet 16 to operate on hf but i wager to make it work right needs more than filters,

filters only work as they should when terminated with their design impedance,

i think mole and justin had a play with texas stars on hf,

good luck

 

[dxhound]

Bias I am not worried about as I will re-design the bias network anyway. I will likely use an HF project 100w input bandpass filter Kit - Low Pass Filter Module 100W Relay Control 160-10M
and build my own switchable bandpass filter network for the output. I am hoing to build the output filters to withstand 2kw CC so in the future I can put two dx1600 together and run 1.5kw with no problems....
This is going to be a fun project!!

 

[-=PEAKABOO=-]

Why not just build something from scratch. There are a lot of parts in texas star amplifiers that leave a lot to be desired.