RM Italy HLA-300 10-160m amp

[mackmobile43]

hla300v Some nice pics.

LOL, they talk funny at that site.

 

[Justme]

Not having a problem with it

 

[TonyV225]

I felt that we were all sitting on a carpet for story time with hitler LMAO!!!

 

[-=PEAKABOO=-]

top of pills works ok for commercial builders,
with the none active pass transistor setup as you will have noticed you get vdrop under higher drive levels even when the pass transistor is fed from a stiff regulated supply, the other problem is as the pass device heats up its conductance goes up pushing bias higher rather than throttling it back, i find tracking both pass and finals helps minimise the thermal drift,

the actively regulated circuit i used based on motorola application notes is much more stable under varying current draw/drive levels but the simpler regulator fed pass setup with tracking is what is found in most hf tranceivers,

good to hear you are still playing with biasing boo

I was just curious of the way others were doing it. I rarely see the RM amplifiers but had someone ask if I would look at one in a month or so and it just struck my interest.

As some may have seen I have been using the same bias scheme since the 90's and for the most part it works pretty good. I however need to work on it a bit so it will control runaway a little better. It does a pretty good job but there has been a few issues in the past where I could see room for improvement but just a few occasions and in both instances there was a noticeable mismatch in the "pills"

 

[fasteddie]

i have an rm 200p i use on one of my riggs for a little extra help have hade no problems with it i drive it with little power and it sounds nice and gets out beautifuly

 

[eagle1911]

First off let me say hi and apologize for necro-posting, but I've been doing a lot of reading lately about the rm amps and I've got a couple myself. My question has to do with the statement in the quote below where it's said that the 68 ohm resistor and cap are backwards.. I'm curious what difference that makes? By my thought process it would do the same no matter if the resistor comes first or the cap, but I could be misunderstanding things completely given my lack of expertise in amplifier theory.

Thanks!

i have played with/repeired the hla150 and hla300, at the heart of the hla300 is a rmkl500 cb amplifier with large wattage feedback resistors, rm added vswr/overdrive protection plus manual or automatic switched filters but they failed to modify the feedback networks to flatten the gain curve at lower frequencies, the cap and 68ohm series resistor works backwards to what is needed in a hf amplifier,
sd1446's are vhf transistors and have very high gain at lower hf, you should reduce drive on lower bands, on certain frequencies and drive levels you can provoke self oscillation, watch the amp meter for a sudden big jump in current draw,

@13.8v same 60a supply as used in the posted test i saw very similar power figures on the lp-100 and marconi 50ohm load from the sommercamp badged rm hla300.

 

[bob85]

you misunderstood what i said,
bipolar hf amps need a rising rate feedback as frequency of operation is lowered, the cap resistor network used in the rm's won't do that, the best it can do is not reduce feedback by much as frequency goes down,
better designs often use lcr networks to give the rising rate feedback

 

[eagle1911]

OK I see. Thanks for the clarification, makes perfect sense. Read a lot of your posts here bob85.. very informative stuff.

 

[doctor]

AMPLIFIER

Any follow up and has anyone used this on 75 meters???, I want to use it for AM only running around 10 watts in...any comments

DOCTOR/795

 

[Bushmaster]

Anyone have any follow-up info on how to correct any of the issues mentioned concerning this amplifier? I'm strongly considering buying one, but not sure if they are worth it, as is from the factory. I've heard a couple of them on the air on 75 meters, and they both sounded as clean as a whistle. Both operators claimed that they love them, and and haven't had any problems.

 

[eagle1911]

Honestly in my very humble opinion the HLA-300 is a damn fine amp. It's always possible to find room for improvement with almost anything, but all around they're very decent.

 

[dd18]

HLA300V

It is a fine amp but can give problems. Just have to watch 2 things real close.
Overdriving it and SWR.
Seems to work best at 5w input and very low swr as it is susceptible to SWR.
There has been a couple of upgrades since it first came out.

Dave

 

[doctor]

AMP

I wonder if it can handle an alinco dx70 am..low power 4 watts, also if it can handle digital , want to use it on am mostly on 75, but havent heard one yet....
DOCTOR/795

 

[Bushmaster]

It is a fine amp but can give problems. Just have to watch 2 things real close.
Overdriving it and SWR.
Seems to work best at 5w input and very low swr as it is susceptible to SWR.
There has been a couple of upgrades since it first came out.

Dave

I should be alright then. I'm only going to use 200 watts anyway, as I am limited by my remote autotuner, which gives me a superb SWR all around. So both of the issues you mentioned should not be much of an issue for me. I am hoping that around 5 watts PEP will give me around 200 watts PEP.

 

[dd18]

You will probably see more than 200W PEP on 80m with 5w of drive. I think you will be pleasantly surprised.