[AMPS] Re: full break in

[Radiodan W7RF]

 Roy   K6XK said
>  PS... I performed some rough estimates this morning on the life
> expectancy
> of a vacuum relay. If we operate 500 words per day, CW, I calculate the
> 2-million relay operations rating would be consumed in about one year.
> Ouch.

PIN diodes don't like SWR and are severely derated with any value above 1:1.
They fail often in demanding service of high power and high SWR. Most of us
have some antenna on some band(s) that doesn't exhibit 1.5:1 or less SWR.
Either use a tuner to protect those delicate PIN diodes or risk an early
failure.
Calculating exactly when PIN diodes fail has always been "just when you
needed them most", contesting, DXing for that rare one, etc.
Vacuum relays on the other hand, can handle some really crummy loads and
keep on coming back for more. I use a HENRY 3K Premier and have operated it
into my 40M yagi which is tuned for CW. On phone the SWR can get up to 5:1
at the top of the band. 3.5:1 on 12M & 17M as well (Force 12 C4XL).
NO problem loading or high power QSK WITHOUT a tuner! No "timing" problems
or worries about the AGC of a radio allowing too much power on a first spike
either.
Just tune and GO!

I would suggest that "actual" incidence of vacuum relay replacement from
wearing out is much lower. We simply don't hear of them being replaced very
often.

73, Dan Magro W7RF, (President WARC 1999, member SCDXC, SCCC)
Manufacturers Rep & Distributor for HENRY RF Power Amplifiers.
www.radiodan.com <http://www.radiodan.com>     RFpower@radiodan.com
<mailto:RFpower@radiodan.com> A trip to our web site is worth the click!






--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm