Collins 30L-1

[WA4JK]

What do you guys think of this amp for AM use. Looks like it will fit my limited current supply in the trailer.

[w3jn]

Don't expect much more than 125 watts or so carrier; other than that it's a FB amp.

[WA4JK]

That's pretty good with the limiting issue of current in the trailer while on the road.

[W2VW]

Even RCA 811As have problems in this amp on AM.

Use 572Bs and extra air.

U get 125 watts carrier with enough headroom for a little over 100% positive without launching anything.

New 572Bs can be had cheaply these days.

[KM1H]

The PS in that barely supports a SSB duty cycle and should at least get new caps and higher value equalizing resistors.

Then an additional fan as mentioned and 572B's.

Or sell it to a Collins nut and get something with more headroom.

Carl

[Todd, KA1KAQ]

They're a nice little amp but I'd strongly recommend going another route. I had a spare that was loaned to a friend for use on SSB. He burned up the transformer while corntesting with it. He did make good as any real friend would, but it certainly made me realize the limitations of this otherwise-handy amp.

This amp came about as a table top companion for the S-Line and KWM-2 where size was important. Pretty amazing little box when you consider when it was made and what's crammed inside. It's an excellent choice for DX work or even ragchew where the duty cycle isn't too hefty. Use it within its limitations and it will go forever. It will work on AM, but probably not for long. And for the power out, there are a lot of better choices.

[WA3VJB]

Dave knows of what he speaks.
We used his 30L-1 during the AM Expedition to Thomas Point Lighthouse and it did great on AM with 572Bs.

Even RCA 811As have problems in this amp on AM.

Use 572Bs and extra air.

U get 125 watts carrier with enough headroom for a little over 100% positive without launching anything.

New 572Bs can be had cheaply these days.

[K1JJ]

The Collins S line, especialy the 30L-1, has such an honest looking face.  I used to own one. Thought it was a nice amp for what it was. With the stock 811A's, 100 watts of carrier was about it to allow for plenty of headroom (600w pep) and keep heat reasonable. I did pop some holes in the plates once.  Finally sold it, replaced with a pair of 3-500Z's.



T

[Todd, KA1KAQ]

Yeah, I don't remember the exact story now Tom, but something like Art wanting a desktop 1KW (input) rig for those radios, and BTW - it needs to fit in the same case, no external supply, etc. Really quite a feat for back then (1961), like the 51S-1 which fit in the same case. Can't recall for sure, but it might've been Gene Senti who designed and had it working at his home in a couple weeks. Someone else did the physical layout IIRC.

Of course, there are some trade offs, and they're no Alpha 77DX. But when you need that little extra *oomph*, they do alright. I just can't picture one lasting too long if used in A3 service long-term.