FT-990 & Amplifier Switching

W8JITom at aol.com W8JITom at aol.com
Sat Dec 28 09:37:22 EST 1996

In a message dated 96-12-26 10:00:47 EST, you write:

>With an SB-220, at least, there is
>sufficient RF leakage thru the amp relay, that you can copy QSK on the
>transceiver with the amp keyed, you lose mebbe 20-40 db, but you can
>usually tell if the DX is transmitting, which is what you need to know.
>(OK you Alpha owners, stop ROTFL...)

Most of the coupling is leakage through the tubes, not the relay. In a
grounded grid PA, the input is in series with the output, so some leakage is
always evident. ETO's are no exception to the laws of physics. 
>Was a little concerned when first tried this that some switching spike
>from the amp might kill the xcvr front end if the xcvr was still in rcv
>when you key the amp, but this has worked fine for 4 years with a TS-440
>and 6 more years with a 950. YMMV.

If there is a switching transcient that would do this, the PA would almost
have to be a dirty PA that needs work.

I built a little circuit that goes across my key (not the output of the
keyer, but the key itself). When I close the key, it directly closes the amp
relay contacts and all the other relays. It has an open collector output, and
that output is in parallel with the rigs relay output. So before the rig even
gets a closure from the keyer the antenna relays are sent on their way to the
transmit mode.

This mod does not disturb QSK operation or any control functions. And still
works late at night when you are half asleep.

73 Tom

>From N6NT at worldnet.att.net (Bruce Sawyer)  Sat Dec 28 16:41:41 1996
From: N6NT at worldnet.att.net (Bruce Sawyer) (Bruce Sawyer)
Date: Sat, 28 Dec 1996 16:41:41 +0000
Subject: 30L-1 follow-up
Message-ID: <19961228164139.AAA19208 at LOCALNAME>

At 01:31 PM 12/28/96 +0000, you wrote:
>Hello to all:
>I have one question about the Collins 30L1 Amp.
>Does it works on WARC bands ???  I know that a few others amps
>(old ones) we can use on WARC bands ( 24 Mhz on 28 Mhz - 18 Mhz
>on 21 Mhz and 10 Mhz on 7 Mhz). What about the 30L1 ???
>Thanks in advance for that info. Best regards from Brazil.
>Fred - PY7ZZ 

The short answer is yes, but that doesn't tell the whole story.  There are
instructions in the manual which explain how to retune the amp to work on
frequencies outside the ham bands.  So you can easily set it to operate on
the WARC bands, but you'll give up something in order to be able to do it.  

There was an excellent article on this amp in CQ a couple of years ago by
Bill Orr, W6SAI.  At the time he wrote the article there were a number of
these units which had just come on the used equipment market as surplus
military gear.  They had been returned to operate on military frequencies
and were used during Desert Storm.  From what I hear, there were lots of 'em
around that were dirt (sand?) cheap, but often in poor condition.  Not any
more.  I think the going price on one in decent condition is around $600,
but this thing is a real workhorse and I think it's still a great deal at
$600.  Take the amp out of the case and there is still an inner cabinet
which protects it during travel on contest expeditions.  It is small enough
that you can take it as carry-on luggage, though it does get to be a pain
lugging it through airports if you have a lot of connections.

Bruce, N6NT

>From jdclarke at freenet.columbus.oh.us (Jeffrey Clarke)  Sat Dec 28 16:44:37 1996
From: jdclarke at freenet.columbus.oh.us (Jeffrey Clarke) (Jeffrey Clarke)
Date: Sat, 28 Dec 1996 11:44:37 -0500 (EST)
Subject: NA/Stu Perry Topband Challenge
Message-ID: <Pine.3.07.9612281136.A25866-a100000 at login>

    Has anyone sucessfully downloaded the file needed in NA for the 
  Topband Challenge from the LTA BBS ???  I am a registered user of NA 
  and dialed in to the BBS to get the file (W1BB.TMP)  but the download
  feature does not seem to be working ??? Are there any other sources to
  get this file ???  

    Also have a question about the exchange in the contest, Is the 
  grid square in the exchange the short version ( for example I am in 
  grid en80) or the more precise one that uses 5 characters ???

                       CUL      Jeff   KU8E

 *      Jeffrey D. Clarke   jdclarke at freenet.columbus.oh.us       *

>From n4gn at iglou.com (Tim Totten, N4GN)  Sat Dec 28 17:11:13 1996
From: n4gn at iglou.com (Tim Totten, N4GN) (Tim Totten, N4GN)
Date: Sat, 28 Dec 1996 12:11:13 -0500 (EST)
Subject: Amplifier Switching
Message-ID: <Pine.GSO.3.95.961228120507.13067B-100000 at iglou1>

On Sat, 28 Dec 1996, Paul D. Schrader wrote:

> It is a standard problem.  You can't solve it without hardware changes.
> To get what you are trying to do to work you need a QSK type of amplifier.
> If you put a scope on the amp output you will probably see a large spike.
> This spike puts noise all over the band and others will love you.

We had this problem at C21BH in WW CW.  One of the stns was a
TS-940/TL-922 combination.  We managed to eliminate all the normal
interstation QRM problems with ICE filters (W9SU does a great job with
these!), but at the beginning of each transmission, the nasty spike Paul
mentions was killing the other station.

Unfortunately, we didn't have TR Log with PTT keying at that stn, so the
solution was to use a footswitch!  I'm glad Mats and Martti mostly
operated that stn, 'cause I don't think I could have ever gotten used to
using a footswitch after all these years!


    Tim Totten, N4GN (nee KJ4VH)
n4gn at iglou.com   n4gn at contesting.com

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