[ETO_Alpha] Alpha 78 on 17m and 12m?

Sun, 14 Jul 2002 23:41:12 -0500

Glenn, George, Tom and Jack,

Thanks for the excellent replies - I will relay all the info to the other club members so we can decide which path we plan to take.  (Sorry for the delay - was out of town for several days.)
73,&nbsp;&nbsp; Duane&nbsp;&nbsp;&nbsp;&nbsp; AC5AA&nbsp;&nbsp;&nbsp; 

&gt;From: alpha-service 

&gt;To: "Duane C." 

&gt;Subject: Re: [ETO_Alpha] Alpha 78 on 17m and 12m? 

&gt;Date: Thu, 11 Jul 2002 09:34:23 -0600 

&gt; 

&gt;"Duane C." wrote: 

&gt; &gt; 

&gt; &gt; A club to which I belong has an Alpha 78 amp. I have not operated the station in a long time, and have never operated the amp. However, a question has arisen from a new member regarding whether the amp will or can be made to work on 17m and 12m. Does anyone know the answer to this? 

&gt; &gt; 

&gt; 

&gt;Hello Duane, 

&gt; 

&gt; Here is some info about using the Alpha 78: 

&gt; 

&gt; The best way to run the 78 is to tune up in the CW position to about 

&gt;500w output, then switch to it to SSB (higher plate voltage) and 

&gt;continue your tuneup to whatever output you desire. 

&gt; 

&gt; The CW / SSB HV settings were made for the old USA FCC power rules, 

&gt;which were 1.0 kw DC INput on CW or 2.0 kw PEP INput on SSB. The ratio 

&gt;of the low to high HV is such that if you tuned up at the CW limit using 

&gt;the lower HV (CW), you could then just switch to SSB and the amp would 

&gt;be tuned up correctly for the higher SSB limit. 

&gt; 

&gt; It is better for the amp to run the higher HV all the time, it keeps 

&gt;the grid and plate current low. Watch the grid current, NEVER exceed 

&gt;50ma per tube (as stated in the manual). 

&gt; 

&gt; For 1500w output, tune the amp with a keyer sending fast dots. The 

&gt;grid current will be about 75ma, plate current will be about 1.2A. 

&gt;Sending dots at 40 wpm gives about 1/2 of the key-down reading on the 

&gt;meters. 

&gt; 

&gt; When using the BANDPASS function on various bands, keep the antenna 

&gt;VSWR below 1.5:1. Higher VSWR can damage the capacitors in the BANDPASS 

&gt;circuitry, they are not voltage rated as high as the much larger manual 

&gt;TUNE and LOAD capacitors. Do not hold the key down at 1500w in the 

&gt;BANDPASS mode. 

&gt; 

&gt; It is normal to have slightly lower output on 10m than the lower 

&gt;bands. 

&gt; 

&gt; Information on tuning up on 17m is on our web site. Do NOT use the 78 

&gt;on 12m, the plate choke will burn up. 

&gt; 

&gt; 

&gt;http://www.alpha-amps.com/html/warcband.htm 

&gt; 

&gt;-- 

&gt;73 - Glenn AE�Q 

&gt;Alpha/Power 

&gt;303-473-9232 x 141 

&gt; 

&gt;------------------------------------------------------ 

&gt;Attention ALPHA &amp; RF CONCEPTS Customers: 

&gt; 

&gt;Alpha production and service will be closed between 

&gt;July 1 and July 12 inclusive. 

&gt; 

&gt;An RA # (Return Authorization number) is required for 

&gt;all returned amplifiers. The RA# must be visible on 

&gt;the outside of the package. 

&gt; 

&gt;A minimum of $52.50 (1/2 hour Tech time) will be charged 

&gt;to all non-warranted and voided warranty work. 

&gt; 

&gt;Shipping charges to and from our facility are the 

&gt;responsibility of the customer. Warranty does not 

&gt;cover shipping charges. 

&gt; 

&gt;A $5.00 handling charge is added to all non-warranty 

&gt;parts orders. 

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