BREMI BRL 200 Valve Amplifier

Hi there,

does anyone have any knowledge of these old Amplifiers?
I bought one a few years back at a Ham Radio Rally. There have been some modifications to it, but having compared them to the 4m and 6m conversions, the mods are different. I just wonder if it has been updated at some point for continued use on 27/28MHz. The mods look like they where carried out back in 1981, as there is a sticker inside from a previous radio ham owner.

Basically trying to confirm what frequency the Amp can be used on.

I have made a short video and the link is below.

Any suggestions would be greatly appreciated.



Thanks Neil
108CT231
GM0PWS

Hiya Neil,

Took me back a few years seeing an old set of Bremis!

I used to have a set of these back in my old CB days, acquired them after a knowledgeable CBer "blew" them up taking out the valves. Took a trip to London on my old Honda CX500 to get "TV" valve replacements and remember paying for them with £1 notes!

Of course this was pre-internet days so had to reverse engineer a schematic, but they're quite simple circuits.

As you point out all the coils and caps look original so not modified for typical Ham use. The original spec for these was 26 - 30MHz and I ran my old multiband Tristar with no problems.

From what I can make out the "mods" done look like typical "upgrades". People used to update the rectifiers, place bleed resistors across caps, reroute wiring for "extra" current capacity(?) and place small value caps across power lines in the hope of reducing noise or RFI.

If they fire up OK and the relay clicks over on TX jobs usually a good'un.
(There's a simple timer circuit to keep the HT on when using SSB, relay rattles like mad if this circuit is faulty!)

As with most simpler valve circuits they're virtually bomb proof. The problems I saw on these back in the day were from pushing too much power into them, (with the hope of more power out and probably how the set I had were blown), to forgetting to power them off as they sit tucked in a shelf with no ventilation for days(!)

The valves can go "soft" which is evident if the power output increases significantly on longer overs but will still work.


I know one thing, replacement valves will cost more nowadays, you can't pay in pound notes and my old hag of a CX is a flipping "classic" bike today!?!

All the best,
Victor

Hi again,

Now my rose-tinted nostalgia trip is out of the way....

They are just simple RF Linear amplifiers with a Pi-network tuning.

The valves were originally designed for horizontal deflection amplifiers in domestic televisions but as with most valves are pressed into different services. The valves tend to not self oscillate even when pushed hard and have a low plate capacitance lending themselves to higher frequency use than originally intended.

As mentioned the coils and caps fitted in your unit look original and were designed for 26 to 30MHz. The conversions people are doing alter the Pi-network tuning for a different frequency use. 50MHz (6m) would be pushing it, 70MHz (4m) probably pushes them to the edge. You'll notice no one has "converted" them for 2 metres!

They are what they are, cheap surplus television tubes, (most TV manufacturers had moved to semiconductors by the end of the 70's / early 80's), pressed into a commercial/profitable use.


That being said, they worked rather well. I liked my set and had many a CB DX with them.
(Power ratings were always exaggerated, usually took 5 or 6W to trip the relay with an expected 100W to 120W peak on SSB output)


Anyway, apologies again for my trip down memory lane and best of luck with whatever you decide to do with them.

All the best,

Victor

Morning Victor, and thanks for the replies! Honda CX500. Yep definitely a classic. When I started work in London late 80’s, I rode 125’s. Quick as anything away from the lights, but you where breaking for the next set before you even got it into 4th!

Thanks for all the info. I did suspect the old girl had had a face lift as it where, but I suspect it’s been a while since the tubes have seen any action. Certainly appear to be the original ones and would imagine they’ll be particularly ‘soft’.

Will fire her up later and see how I get on. I ran an old 4CX250 Amplifier on 2 meters for years and it had way more punch on the air compared to its linear counterpart. I did like the old days. Things where simpler. The radio was busy with folk and you could work the world almost on a few watts.

Heh ho. Will let you know how it goes and maybe catch you on the air at some point!

Cheers for now and thanks again. Neil

Hi Neil,

Hee, used to watch the 125 bikes nip through gaps in London that I wouldn't dare try with the old CX!

4CX250 valves, now they were "engineeringly" pretty to look at.

Yeah, the good old days! Now it's all spurious RF hash from multiple cheap Chinese electronics everyone owns.
At least now it's harder to cause RFI as TV is "piped" on demand!


No worries my friend, hope you get on well with the Bremi's.

Not back "on-air" yet, been almost a 30 year gap but seeing all this old radio chat is like listening to an old record you haven't heard in years, memories and thoughts come flashing back.
Looking forward to getting back on the airwaves and yeah, be nice to catch you there.

All the best again,

Victor

Hi

I had one of these valve amplifier, they where designed for 26-28mhz but they would work fine up to 29mhz, although I never went above 29mhz so can’t helpwith anything above 29mhz. A great linear though.

P.S don’t leave any bread on it while you use it, it will definitely be toast when you’ve finished.

73

Alan G7ABR

Thanks Alan. Yes I see the 4 and 6 meter conversions all have fans fitted!
Heh ho.....living in the Highlands, it’ll keep the shack warm if nothing else

73’s Neil

i have a load of spare values and other bits for the bremi including pbc board..rollers ect...

If i remember correctly the tubes were simply crappy EL509 TV tubes like you mentioned Victor, must have a look in the garage, got given two amps like this by a friend and changed the tubes out for Russian tubes that developed a REAL 180-250watts.

Regards Ady