Jeff -

Trapped Antennas - ARRL
http://www.arrl.org/tis/info/Trapped.html

w9gb

Matt Eriskcon, KK5DR also assmebled his opinions for changes.  Alpha does not recommend that QSK mod (last time I asked them about it)

http://www.kk5dr.com/alpha76/OLD76.pdf

OK.

1. The Safety Interlock (lid must be closed) is in series with the K1 (Power-on) relay coil.
2. F3 is a 1.25 slow blow fuse, assure that this fuse is good.
3. To Power ON the Alpha 76CA / PA a 2-step process is used.  K1 (Power-on) and K2 (Step_Start) must BOTH be closed for the HV transformer to receive power.
4. In order for Voltage to be present for both K2 (Step-Start) and K3 (Plate Voltage Relay) - the CW/SSB switch (which mode) must be properly selected.

5. WHEN the amplfier is UNPLUGGED and capacitors discharged -- LOOK carefully at R115, R116 and R117.  The wattage of R115 and R116 need to be at least 1/2 watt.  Alpha MAY suggest that R116 be a 1 watt (can't find my note, BUT ALpha service does change one of these out for next high wattage)

w9gb

Alpha does have a new on-line form for Tech Support.
http://www.alpharadioproducts.com/trouble_shoot_form.asp

We have just introduced a new "Trouble Shooting and Technical Assistance Request Form" for amplifiers. Before you consult with a tech we would request that you fill out this form, it will allow us to more quickly diagnose your problem. [Form link above]

NOTE: E-mail is not flawless and occasionally we cannot get a reply back to our customers.
PLEase include your phone number and/or address in your e-mail in case we have such a problem.
We will normally send a response to you within one working day. If you have not heard from us after two days then please call us at 303-473-9232 x151.

Jim -

I have that exact Alpha amplifier in my radio shack (one of my Elmers was original owner in late 1970s).
I recently refurbished (new electrolytic capcitors, etc.)
You indicated that you have the Hypersil or regular HV transformer?

There are a couple of resistors that you need to check on the PC board (bias supply).  

The realy you are talkign about sound slike the contactor, I am at client site today -- but can check my notes over next couple of days.

Alpha Power does still service thie model (and provide phone assitance for your troubleshooting) -- and whne I was there 18 months ago -- I did pickup a couple of parts.

w9gb

Well, the HF-1250 appears to be an orphan.
The last request for assistance by other owners -- neither Commeander or QRO seem to have documentaiton or support.

w9gb

IF you lost the processor -- then it may be uphill raod. Yaesu can not even reprogram a chip (built in 2K EPROM) if you found one!

CPU MUSEUM
http://www.cpu-museum.com/14805_e.htm

CPU MUSEUM - chip was made in 1978

http://www.cpu-museum.com/14805_e.htm

Motorola MC146805G2P

It's a 6805 microcontroller with 2 KB masked ROM. Because of that masked ROM it'd be very difficult to replace it - you will need either to find MC146805G2P with exactly the same ROM mask, or, if ROMless or development version of MC146805G2P exists, get ROM contents somehow, and replace MC146805G2P with development/ROMless chip + EPROM.

Yaesu USA claims they can not even program the chip -- IF you did find one (Fox Tango Int'l)

FYI, read this message from C.L. Maher (Fix Tango Int'l) --- 3 years ago.
http://lists.contesting.com/_yaesu/2004-05/msg00016.html

The CPU is NO LONGER AVAILABLE --- ANYWHERE.
When I turned the main dial the rig would jump all over the place and the CPU was totally confused.  
I bought a junker 757Gx locally that had a good CPU, installed it in my rig, replaced the 5v regulator and repaired the trace and things started coming back to life.  Just as a note to anyone with a 757, if you have a failure of the 757 CPU, don't waste your time talking Yaesu for the part.  
THEY DON'T HAVE IT ANYMORE.  They told me even if they did have the chip, they had no way to program it.  So be very carfeul when working in your 757 when it's on.

"Soldered in" lithium coin cells are not uncommon for mobile or handheld equipment.  
These designers were concerned that traditional coin cells may 'fall out' or be dislodged from a coin cell holder.
Replacements available from Yaesu or battery suppliers (Sanyo or Panasonic)

gb

At least you are learning about thermal deisgn (heat sink area, cooling required, etc.).
I really get upset with many of the thermal designs from presumedly qualified engineering grads.  Actual construction and application is sometimes a better teacher than the formulas alone.

gb

A ComSpec CTCSS (PL) encoder/decoder -- like the TS-64
http://www.com-spec.com/ts64.htm

OR an encoder only, like the SS-64 -- will work well.
http://www.com-spec.com/ss64.htm

Icom IC-211 Installation instructions for these CTCSS encoders:
http://www.com-spec.com/insheet/ic211.pdf

w9gb

KEEP that "Golden screwdriver" in your pocket!
That is a sure sign of Homer Simpson.

With a rated dummy load and a good wattmeter (Bird 43 w/peak reading) -- you can make appropriate measurements.

Join the Yahoo TS-440S Users Group.

w9gb
.. and TS-440SAT owner (saved from the dumpster)