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Reviews For: ALPHA 78

Category: Amplifiers: RF Power - HF & HF+6M

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Review Summary For : ALPHA 78
Reviews: 39MSRP: 3495
Description:
3X 8874
Product is not in production
More Info: http://www.rkrdesignsllc.com
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00394.9
W0AD Rating: 2013-09-25
Wonderful amp Time Owned: more than 12 months.
I worked at ETO in the late 70's when we built these amps and never thought I could afford one.

I was lucky enough to buy this amp from a local for parts due to the soft 8874s, and was able to purchase a pair of 3CPX800A7s from a YCCC buddy.

I asked Gary, our Twin Cities repair whiz to do the upgrade, as well as the low drive mod.

http://www.eham.net/reviews/detail/9691

Result: Shockingly amazing performance. 1500+++ on all bands with 33w of drive and 30ma of grid current. Easy no tune 80-10, and 17M is a dial up on the manual 15M position.

When I worked at ETO, we always thought that the iron core transformers in the 76 series were better than the Hypersil due to lower voltage drop with the iron core transformer, and I was concerned doing the mod with the Hypersil. However, it just worked fine and did what it was supposed to do. Voltage+current = output.

I'm more impressed now than I was 30 years ago with the architecture for this box. No component arcing issues, even though the output can be way more than the design parameters. The Hypersil transformer just works. I use the higher voltage SSB position, which seems to be a good place for the 3CPX800A7s.

I was always worried about the 8874s even though everybody said that they were strong tubes. 30 years on a 8874 with a replacement cost of $800 each from Richardson? With the 3CPX800A7s, I don't have to worry any more.

Would I like an auto bandswitched amp? Of course! However, for much less than $2K invested in QRO, I'll reach over and change the bandswitch!


Best regards,

Paul W0AD
N3NEP Rating: 2013-03-27
High Quality Time Owned: more than 12 months.
I bought this amp used and have owned it for over 2yrs now and it is without a doubt the best amp I have ever owned. The bandpass tuning is very handy during contests.
N0IRM Rating: 2012-09-18
TOP QUALITY EQUIPMENT Time Owned: 0 to 3 months.
I purchased a late serial number Alpha 78 recently that has been to N4UQ for the 3cpx800 upgrade along with adding the WARC bands and replacement of the input RF connector.

First off, the original construction quality of the amp is VERY nice, from the the internals to the cabinet is top quality. The bandpass “no tune” feature is great for contesting and quick band switching.

Then adding on top of the Alpha quality, N4UQ completed all of his mods including a new set of 3CPX800 tubes. Mr Byrd's work is nothing short of top quality also, matching or exceeding the original workmanship. Even down to the screen printing of the face to include the WARC band positions. The amp will work along producing legal limit now without effort.

I cant say enough about the Alpha 78, it is a top quality piece of equipment that was way ahead of its time from Alpha, that was improved upon by N4UQ. I would highly recommend one of these amplifiers or any work by Dick Byrd.

Kent
N0IRM
KX2T Rating: 2012-08-31
Great Amp Time Owned: more than 12 months.
Had owned two different 78's, both were late serial# and both worked outstandingly well, used in day to day rag chew's,dx'ing and contests. These amps have vacume realays and nice qsk for cw, will put out the leagal limit with no problems on ssb/cw maybe for RTTY you might wanna settle it down around 1K only to save tube life(those 3CX400 aint cheap) but they are built to last. The bandpass auto tune feature is great for contest, it makes band changes between 80 thru 15 easy but you do have to manual tune on 160 and 10, no biggy. I wish I didnt sell my last 78 but the ones on the used market today are way overpriced when you consider the price of the tubes but if you can find one for around $1200-$1500 thats an excellent used amp for those prices. The one thing thats good is the company still supports the older amp's but rememeber there old amps so components will fail so dont overpay for a used amp even if its an Alpha.

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Earlier 5-star review posted by KX2T on 2002-01-17

I have owned in the past 30 plus years 4 alpha amps at my home station. One 77DX, one 91B and at different times two 78 amps. All have been excellent performers both for DX and DX contesting. Alway there with clean robust construction and performance. Easy to drive and the only con is that the tubes are expensive and the 3 min warm up time. The 78's are good HF amps with small foot prints on the op table, 1.5kw out with Vacum relays that work well with qsk, and they don't sound like a jet air liner taking off in your shack with fan noise. The 80 threw 10 mtr instant tune works very well and helps get those last few mults fast when contesting. Recomended, one that will be a classic.
WC2L Rating: 2012-08-30
Workhorse Amp!! Time Owned: more than 12 months.
Love the amp! The amp had the sticky paint. Replaced the front panel and had the cabinet painted black. The amp just keeps working. The amp is now at a contest station in the NE.
N6WIN Rating: 2012-06-18
Excellent contest amplifier Time Owned: more than 12 months.
This amplifier is being borrowed from a great CW Sprinter (N6RT) and was once used at W6EEN's (SK) contest station. It is now in use at my QTH for domestic contests and dabbling in DX contests. It is providing my SO2R station setup with a great 2nd radio amplifier that is complimenting my Acom 2000A auto-tune amplifier nicely.

It is on 220v and puts out ~1200-1300w when operated in "SSB" mode with up to 75w drive (watch grid current to not exceed 100ma CW or 50ma SSB) using original stock 8874 tubes. It works excellent with my various resonant mono banders using the band pass mode on 80-15m with the 10m or 160m tuned manually.

I cannot see upgrading this amplifier until my friend says I can no longer borrow it.
N5XZ Rating: 2012-04-16
Fantastic Old Amp Time Owned: more than 12 months.
I purchased my '78 on eBay a couple of years ago. It was listed for $1800 to bid or $2000 "Buy it Now"...I hit "Buy it Now" as fast as I could get my pointer there. I knew it would be bid higher if allowed to. Guess I got lucky. The amp has been a real workhorse and works great on all bands, including WARC bands (12 meters with the help of N4UQ. He did other upgrades as well and I am extremely pleased with them, as well as this 30-odd year old amp. I am proud to have a almost exclusively USA made station (K3, Alpha 78, Hy-Gain tower and SteppIR). Once again, a great amp!
W2MV Rating: 2012-02-24
A keeper! Time Owned: more than 12 months.
Purchased the amp used three years ago...a creampuff. It loafs along at 1KW output, QSK works great, and it's solid and reliable. My only minor complaint would be the RCA phono jack used for RF input...a bit strange, would have liked an SO-239.
I would recommend this amp as well as other Alpha products...have used some of the more modern models and they're built like tanks.
W1ITT Rating: 2012-02-04
New front panel Time Owned: 0 to 3 months.
I have an older Alpha 78 that works fine, but needs aesthetic improvement. It has the old sticky paint on both the front panel and cover so I bought a new front panel from Molly and it's nicely screened and pretty. I'll get the top cover stripped and repainted locally. It's probably time to replace the electrolytic capacitors in the high voltage supply as well but this beauty should live to fight many more battles. It's great that RF Concepts/Alpha still supports their classic rigs.
K3PG Rating: 2012-01-15
Best Old Amp Time Owned: more than 12 months.
I bought mine used several years ago from K5VT (sk) of the VooDoo Contest group. The amp had been to West AF several times and had spent a year in the Caribbean. The QSK board had been 'field repaired' in Africa and Vince sold it to me as sort of a project. Everything was good except for a few small parts and once I got it figured out it works great. I bought an extra set of tubes and plan on keeping it. The Band Pass mode is almost all I use. Only have to put it on the correct Band and choose CW or SSB and it is 'No Tune' Puts out close to legal limit with under 100W drive and is solid.